Public Services

Center for Aquatic Ecology

Center for Biodiversity

Center for Economic Entomology

Center for Wildlife Ecology

Project Summaries

Publications of the Staff

In Memoriam

Credits

The face of Illinois was forever changed with the arrival of humans, particularly European settlers. Gone are most of our prairies, wetlands, floodplain forests, and upland woods. Much of what remains of these habitats has been severely modified, and even many relatively high-quality areas are deteriorating because of invasion by non-native species or improper management practices. Indeed, it is estimated that 99.93% of Illinois' natural habitats have been significantly degraded or destroyed. That leaves less than one-tenth of 1% of the state in high-quality natural habitat.
Given this tremendous loss, it is imperative that we manage what remains of our natural heritage in ways that ensure its survival and facilitate its improvement. In Illinois we have many areas that, while not pristine, have the potential to have their natural quality improved through careful management. We also have the opportunity to try to reconstruct natural habitats, or at least some important aspects of them. All these management issues fall within the relatively new science of restoration ecology.
The Illinois Natural History Survey is actively involved in many aspects of restoration ecology, both in basic research and in application of these results. One of the big questions in restoration ecology relates to the goal of these efforts--determining what Illinois looked like before European settlement. How were the different habitats distributed and what species made them up? A good source of information on presettlement vegetation are the Government Land Office surveys, most of which date from the 1830s. Careful analysis of these data by Survey staff is revealing interesting insights into the relative distribution of woodlands and prairies in the floodplains of our major rivers, as well as elsewhere in the state. This research is helping us determine whether we are making progress in understanding the presettlement vegetation of the state and if we are preventing habitats from degrading further. Baseline data on current populations of plants and animals are essential. Staff from throughout the Survey are involved in projects documenting existing conditions and monitoring changes over time.
It has been recognized since early in this century that the prairies and savannas that once covered Illinois were maintained through regular burning, either by natural fires or those started by Native Americans. Fire has become the foremost management tool for these habitats. Research by Survey staff is also showing that fire is important in maintaining some other types of woodlands, especially barrens and flatwoods. Although the overall effects of fire on vegetation are fairly well known, much remains to be learned about the effects on individual plant species and on animals, especially insects. Efforts by Survey staff are under way to help fill these major gaps in our knowledge. Not surprisingly, early results suggest that fires, especially if large and frequent, may lead to the decline of some plant and animal species. Other species are much less sensitive to fire.
Other aspects of the ecology of individual species must be better understood before we can develop appropriate restoration procedures and goals. For example, the habitat requirements of bird species characteristic of prairies, woodlands, and floodplain forests are being intensely investigated by Survey staff. For some of these species, the particular plants in the habitat are relatively unimportant so long as the overall structure of the vegetation meets the animals' needs. For some species, however, specific plants are essential, and for others, the overall diversity of plant species is crucial. Together with the results of research on the habitat requirements of specific plant species, this work will allow restoration efforts to be much more successful than they have in the past.
Survey staff are also involved in a variety of specific restoration efforts. Most notable among these is our involvement at the Midewin National Tallgrass Prairie (formerly the Joliet Army Arsenal) and the Savanna Army Depot, which is in the process of being decommissioned.
Through cooperative agreements between IDNR and the U.S. Forest Service and the U.S. Fish and Wildlife Service, newly hired Survey staff are joining other DNR staff and federal biologists in restoration efforts at these two large and biologically important sites. The INHS staff are responsible for overseeing monitoring efforts and conducting research related to restoration. They also provide a vital conduit connecting research with practice at these sites. We welcome this opportunity to extend our work on behalf of the people and natural resources of Illinois.

NATURAL AREAS

History of Emiquon National Wildlife Refuge
S. Havera, K. Roat, L. Anderson, D. Esarey
Emiquon National Wildlife Refuge was established by the U.S. Fish and Wildlife Service (USFWS) in 1993 in Fulton County. Included in the boundaries of the proposed refuge area is farmland created after Thompson and Flag lakes were drained in the early 1920s. These lakes were productive and renowned habitat for fish and waterfowl. The USFWS is seeking funds for expansion of the refuge and possible restoration of the two former lakes. If restoration of the lakes is accomplished, many opportunities for research, education, recreation, and tourism would be available. An account of the biology of the Thompson Lake area and its history is being prepared for publication.

Nesting ecology of grassland birds in the Savanna Army Depot and the Midewin National Tallgrass Prairie
J. Herkert, S. Robinson
Two former army installations are now the sites of some of the largest grassland restoration efforts ever undertaken. For the last two years, researchers have been studying the nesting ecology of birds in these areas to provide guidelines for restoring functional bird communities. Researchers have located more than 1,000 nests of grassland birds in these two sites. In general, nest predation rates are very high, but levels of brood parasitism by Brown-headed Cowbirds are very low. Some species appear to require short grass and can use non-native cool-season grasses (such as Kentucky bluegrass and brome that grow in the spring and fall), whereas others require taller, dense grasslands. These results suggest that cool-season grasses may be a good surrogate habitat for grassland birds until the native grasses can be restored to the area.

Tree species preferences of forest birds in the Cache River wetlands
A. Gabbe
The Cache River Wetlands of southern Illinois is the site of one of the largest floodplain forest restoration projects ever undertaken. Over 40,000 acres will be restored to forest. In 1997, a study was begun of tree species use by forest birds to help provide guidelines to restorationists about the most important tree species to include when planting trees. Preliminary results suggest that the very diverse tree species available in the floodplain forests of southern Illinois provide rich foraging conditions for many insectivorous birds, but that a few species are especially important. Bald cypress especially is heavily used by several rare bird species, such as the Yellow-throated Warbler, and should be featured in any restoration. Several other tree species including sycamores and boxelders that "volunteer" without being planted, however, are also heavily used by birds.

Midewin bird monitoring
C. Whelan
Monitoring the response of birds and other wildlife to the impending prairie restoration at Midewin National Tallgrass Prairie, Will County, Illinois, is critical. In this project, conducted with the help of volunteers, different monitoring procedures will be compared. There are two procedures: point counts, in which all the birds detected within a fixed radius from a point are counted in a designated period of time (regardless of their use of space), and spot mapping, in which the movements of all detected birds are mapped. The results will help guide further monitoring.

Natural areas of Savanna Army Depot
K. Robertson, L. Phillippe, G. Levin
A major report was completed entitled "Delineation of Natural Communities, a Checklist of Vascular Plants, and New Locations for Rare Plants at the Savanna Army Depot, Carroll and Jo Daviess Counties, Illinois." Extensive amounts of sand prairie, sand savanna, sand forest, and floodplain forest occur at the depot; the sand prairie is the largest contiguous prairie still found in the state. Extant populations of 12 state endangered or threatened plant species were observed.

Kaskaskia forest study
J. Taft, S. Robinson, C. Phillips, R. Sparks
Perhaps the largest contiguous forest stand in Illinois occurs along the Kaskaskia River in southwest Illinois where impressive stands of bottomland forest, post oak flatwoods, and some upland forest remain. Forest vegetation is being described to complement data from bird, herpetological, and fish surveys. The results will provide landowners in the region natural resource data needed to develop a regional conservation plan.

BURN STUDIES

Prescribed burning, savanna restoration, and bird communities in Illinois
J. Brawn
Oak-hickory forests were historically self-sustaining, but current trends indicate that stands throughout the Midwest are not regenerating. Instead mesophytic species, such as sugar maples (Acer saccharum), are becoming dominant. The absence of periodic disturbance, especially fire, is thought to underlie this change. This study will assess the effects of prescribed fire and removal of mesophytic woody species on forest birds in Illinois. In 1994, avian community structure, population dynamics, and reproductive success were monitored within several restoration and control sites in the Peoria Wilds forest system. In 1995, the study was expanded to include several established savannas, such as the Sand Prairie Scrub-Oak Nature Preserve in Mason County, the Forest Preserve District of Cook County (FPDCC), and the Iroquois County Conservation Area. In 1996, studies on foraging ecology were initiated within restored and unrestored sites. Fieldwork in the FPDCC will continue in 1998 with emphasis on studies of nesting success and restoration.

Effects of annual burning on populations of partridge pea, Cassia fasciculata
K. Robertson, D. Gardner (Kempton, IL)
Data were collected during 16 years of observation on the response of partridge pea to annual burning. Total populations varied greatly in response to growing conditions, especially variations in early-summer rainfall. Following burning, populations consistently increased over those in control areas that were not burned. This was further demonstrated by reversing the burned and unburned quadrats, resulting in a reversal of population counts. Burning no more than every second year on high-quality sites may inhibit excessive population increases of the species. The flowers are unusual in that there are different left- and right-handed types.

Effects of fire on prairie insects
C. Dietrich, M. Harper, R. Larimore, P. Tessene
Frequent prescribed burning of remnant prairies may be devastating to insect populations. Some previous studies have shown that insect populations eventually recover after a burn, but the factors that contribute to post-burn recovery are not well understood. Post-burn monitoring of enclosed and unenclosed plots at two Illinois prairies (Windfall Prairie in Vermilion Co. and Richardson Wildlife Foundation in Lee Co.) during the 1997 field season indicated that although some insects survive fire in situ, particularly if the burn is cool or patchy, many insect species do not survive and must recolonize from adjacent unburned refuges.

Gibbons Creek Barrens burn study
J. Taft
Barrens, savannalike communities in a forested landscape, are one of the rarest and least studied community types in the Midwest. They are gradually vanishing due to the absence of fire. This study measures the response of ground cover, shrub, and tree strata to prescribed fire in a barrens remnant in southern Illinois. Fire is excluded from a nearby barrens providing a control site. The response to fire includes an increase in herbaceous species density, cover, and diversity. This study will contribute to understanding the structural dynamics of barrens and the influence of fire on species diversity patterns.

Flatwoods burn study
J. Taft
Flatwoods are oak woodlands with a claypan that occur on level sites and appear to be dependent on periodic fire for the maintenance of compositional and structural stability. This study of a post oak flatwoods near Mt. Vernon, Illinois, examines the response of ground cover, shrub, and tree strata to prescribed fire. Permanent plots were established and baseline data were gathered prior to the first management fire. A fire-free unit serves as a control for this study. This study will help determine the degree to which post oak flatwoods can be restored following an extended fire-free interval.

NOTE: Please see in Watershed Management section--

Fire and flood: role of disturbance in maintaining biodiversity on floodplains
J. Nelson, R. Sparks

Presettlement vegetation patterns along the floodplains of the Mississippi and Illinois rivers
J. Nelson, R. Sparks

PRAIRIES

Composition and diversity patterns associated with the actinorhizal shrub New Jersey tea in tallgrass prairie
J. Taft, J. Dawson (University of Illinois)
New Jersey tea forms an association with a bacterium that fixes atmospheric nitrogen in root nodules. The goal of this study was to determine if New Jersey tea influences community organization in high-quality prairie remnants. C3 graminoid species were more abundant among Ceanothus americanus shrubs than were C4 graminoid species while the reverse was true in vegetation away from C. americanus. Plant diversity was lower in vegetation associated with C. americanus. Furthermore, unlike many other actinorhizal species in these prairie remnants, C. americanus is a persistent component of undegraded, fire-adapted mesic tallgrass prairie rather than a pioneer species facilitating floristic change.

Earthworms in Illinois agroecosystems
E. Zaborski, S. Roberts
Earthworms influence ecosystem maintenance functions performed by soils, such as nutrient recycling and retention, water infiltration, and carbon storage. To better understand how earthworms respond to soil management practices, scientists are sampling topsoil-dwelling earthworm populations in Illinois farm fields and their grassy borders. In 1997, numbers and weight of earthworms did not differ between fields with different tillage or crop rotation, but were much lower in all fields than in their uncultivated grassy borders. Studies continue in 1998 to evaluate the potential of using earthworms as an indicator of soil health.

Flower forms of hoary puccoon
B. Molano-Flores
Hoary puccoon (Lithospermun canescens) has two flower forms, pin and thrum, which theoretically should be present in approximately equal numbers. To determine if differences exist in the proportion of pin vs. thrum flowers in prairie remnants and restorations, seven prairie remnants and two restorations were examined. In most of the prairie remnants, populations had almost a 50:50 proportion of the two forms. However, in the two prairie restorations one form was more abundant than the other. The next step will be to determine the implications that selecting one form over the other may have for hoary puccoon in restorations.

Pollen-ovule ratios in prairie plants
B. Molano-Flores
Successful prairie restoration and management depends on implementing the best available techniques and understanding how organisms respond to management practices. Three species of prairie plants (Eryngium yuccifolium, Gentiana puberulenta, and Lobelia spicata) are being examined to determine if there is variation in pollen-ovule (PO) ratios, which reflect plant breeding systems, among their populations. Knowing if PO ratios vary between populations can be a powerful tool in assessing sites that will be used for seed collection. By ensuring that plants from different sites have the same breeding system, reproductive problems, such as failure to produce fruits, can be avoided in the restored area.

Prairie plant reproduction
B. Molano-Flores
In prairie restoration, many plant species can be reintroduced successfully; however, researchers do not know how well these prairie species are reproducting. The main goal of this project is to determine if there are reproductive differences between prairie plants in restorations vs. remnants. Four prairie species were selected for this three-year study: Dodecatheon meadia, Eryngium yuccifolium, Tradescantia ohiensis, and Veranicastrum virginicum. Reproductive success will be gauged by determining the amount of pollen arriving to the stigma, fruit set, and seed set.

Glacial outwash sand prairies of northern and western Illinois
M. Moore, K. Robertson
Of the 21,000,000 acres of prairie originally found in Illinois, only about 2,500 acres of high-quality prairie still exists today. Of this remaining prairie, the sand prairie community makes up the highest proportion of extant acreage, with many of the largest prairie sites in Illinois belonging to this community type. Research has been conducted over the past year to determine the vegetative similarities and differences of these remaining high-quality sand prairies in Illinois. Quantitative sampling of vegetation has been performed on several large sand prairies located along the Illinois, Rock, and Mississippi rivers.

Prairie and oak forest restoration
W. Handel
Controlled burns and thinning of woody vegetation to restore several prairie and dry open oak forests have been under way in Palisades State Park in the Wisconsin Driftless Division of northwestern Illinois. Preliminary observations are promising with several conservative plant species returning to the disturbed habitat. The goal is to get baseline data from adjacent areas prior to burning to determine the effects of fire on species composition.

An investigation of loess hill prairies
S. Hill
In 1955 Robert Evers published a study on the loess hill prairies of Illinois in an INHS Bulletin. Several of his sites subsequently became nature preserves or were designated as natural areas. Many are still unprotected. Three loess hill prairies in Morgan County under private ownership, one of which was specifically studied and cited by Evers, are being investigated to determine which species are present today, and how these species and the vegetation have changed since Evers' study. Results of this study will increase understanding of loess hill prairie ecology and aid restoration efforts.

Long-term Monitoring

In 1994, Phase I of the state's Critical Trends Assessment Project (CTAP) ended with three conclusions: (1) emission and discharge of regulated pollutants over the past 20 years has declined, in some cases dramatically; (2) existing data suggest that the condition of natural ecosystems in Illinois is rapidly declining as a result of fragmentation and continual stress; and (3) data designed to monitor compliance with environmental regulations or the status of specific species are not sufficient to assess ecosystem health statewide. The Afterword of that report noted, however, that "baseline data to monitor broader ecological conditions has not generally been collected on a statewide basis."
In response, the INHS began several programs supported by new funds from Phase II of CTAP. Through these resources we are better able to collect and organize the kind of data Phase I concluded was so needed yet so scarce. CTAP biological monitoring is of two types, professional and volunteer. On the professional monitoring side INHS developed the monitoring plan, gathers all the data, and does the analysis and maintains the data for future reference. On the volunteer monitoring side we share responsibility with several other agencies and organizations, but we have primary responsibility for developing the monitoring plan, training volunteers, maintaining quality control, analyzing data, and maintaining the data for future reference.
Long before the inception of CTAP, however, the INHS was collecting long-term data. Some data on game species go back at least 50 years, and over 15 years ago we began a major program of monitoring the living resources of large rivers with our Long-term Resource Monitoring Program (LTRMP) efforts centered at Alton and Havana, which continuously monitor biological resources of the Upper Mississippi River System including the Illinois River. Also, the Survey recently published The Fishes of Champaign County, Illinois, During a Century of Alterations of a Prairie Ecosystem (INHS Bulletin 35(2) by R.W. Larimore and P.B. Bayley). At the Survey we consider all of these long- term data sets to be conceptually similar to our biological collections: they transcend individual investigators, their value increases as the years pass and as additional material is added, and we are committed to making both available to specialists investigating any issue of potential value to the advancement of science or the people of Illinois. The following reports are the currently active projects producing long-term monitoring data.

CRITICAL TRENDS ASSESSMENT PROJECT

Illinois EcoWatch Network
D. Stoeckel, R. Sparks
Illinois EcoWatch Network, a statewide volunteer monitoring program, is a part of the Critical Trends Assessment Project coordinated by the IDNR. Primary responsibilities included the development and implementation of quality assurance programs for RiverWatch and ForestWatch components. In 1997, RiverWatch volunteers monitored approximately 300 stream sites and identified macroinvertebrates at 80% accuracy. ForestWatch will become fully active in the fall 1998. Activities of this position include database development and management, data collection procedure development, quality assurance implementation, development of training materials, and assisting IDNR in the development of other statewide volunteer monitoring programs such as PrairieWatch and WetlandWatch.

SoilWatch: monitoring the health of Illinois soils
E. Zaborski, L. Johns
Soil is among Illinois' most valuable resources. A component of virtually every terrestrial ecosystem, it supports biomass production, including food, fiber, and energy; it filters, buffers, and transforms environmental pollutants; and it provides a habitat and genetic reserve for a vast number of organisms. Effectively managing and protecting soil and the important functions it performs requires that we understand the status and trends of its condition. With SoilWatch, researchers are developing a set of procedures with which professional biologists and citizen volunteers can collect meaningful data for a clearer understanding of the health of Illinois' soil.

EcoWatch procedure refinement
M. Jeffords, C. Nixon, S. Post
The Illinois EcoWatch program trains volunteers to monitor specific Illinois habitats to detect long-term biological trends that indicate overall ecological health. A set of scientifically valid procedures is provided to volunteers, who collect data from a given site or sites and submit them to IDNR for analysis. The procedures must be presented in a user-friendly manner, must be doable by nonscientists, and yet must provide important information about a site. Significant refinements to the Illinois RiverWatch and ForestWatch procedures were implemented and better volunteer training methodologies for the Illinois EcoWatch Network were developed.

PLAN-IT (Pairing Learners and Nature with Innovative Technologies)
M. Jeffords, C. Nixon, S. Post
PLAN-IT is a component of the Illinois EcoWatch Network. Because one of the volunteer audiences is high school teachers and students, and because the EcoWatch methods for the various habitats are cookbook procedures, it is important to provide students with an ecological framework for the overall monitoring program. PLAN-IT provides teachers with sets of hands-on teaching materials about Illinois rivers, forests, prairies, wetlands, urban environment, and agricultural soils. These materials are produced by Survey scientists in conjunction with a statewide writing team. Each summer, hundreds of teachers are trained to use the materials about the various Illinois ecosystems.

Conceptual design of a long-term monitoring program
W. Ruesink, D. Niven, J. Brawn, S. Robinson, L. Page, K. Robertson,
S. Kohler
The Critical Trends Assessment Project (CTAP) seeks to assess the extent and condition of natural habitats throughout Illinois. CTAP monitoring efforts will produce summary indicators of environmental conditions in the natural habitats of Illinois. Indicators simplify information about complex phenomena, reflect general patterns in a community, and should have statistical properties sufficient to detect biologically significant trends. Indicators will be aggregated at multiple levels to provide simplified, composite indices of the overall condition of the natural ecosystems. These condition indices are then combined with information on the extent of habitats throughout the state (from GIS land cover mapping) to assess and monitor change in natural habitats in Illinois.

Selection of sites for long-term monitoring
W. Ruesink, J. Brawn, M. Joselyn, E. Brewer, D. Niven, L. Suloway,
C. Phillips
Public Land Survey Townships were chosen as sampling units for CTAP monitoring. A random sample of townships was chosen for each major habitat type to be sampled: stream, forest, wetland, and grassland. By monitoring indicators in random, independent plots, Survey scientists can draw inferences about critical trends of key ecological indicators at the statewide level. The state's GIS land cover database (developed as part of CTAP) is being used to locate the focal habitats for monitoring in each township. Because the habitat categories recognized by the land cover database are broad, criteria have been established to objectively accept or reject sites after ground truthing. In this way, monitoring will be restricted to sites representative of the intended habitat type.

Monitoring aquatic insects
R. DeWalt, W. Ruesink, S. Kohler, D. Niven
The EPT index (number of Ephemeroptera, Plecoptera, and Trichoptera species in a sample) is one of the most efficient indices of stream health because of its ease of use and low variability. The value of this index correlates well with various measures of stream ecosystem function (e.g., nutrient processing) and is sensitive enough to demonstrate habitat-specific impact. For example, the EPT index has been demonstrated to be an effective tool for monitoring the impact of pesticide applications on streams. As part of CTAP, EPT taxa are being sampled in randomly selected townships and streams throughout the state to detect statewide trends in the condition of stream habitats.

Fish monitoring
M. Retzer, L. Page, W. Ruesink, D. Niven
The INHS is collaborating with the IDNR fisheries unit to analyze and voucher fish samples gathered by IDNR fisheries biologists from 514 stations located on large streams throughout the state over a five-year cycle. To sample smaller headwater streams, two randomly chosen sites from each hydrologic unit sampled each year (five units total) are being sampled by CTAP personnel. CTAP biologists will use all of these data to examine long-term statewide trends. Issues of concern include the effect of land use on fish populations, community integrity, and endangered species, and the possible impact of global warming on fish communities.

Monitoring terrestrial insects
C. Dietrich, W. Ruesink, D. Niven
Because arthropods are the most diverse group of terrestrial organisms both in numbers of species and in behavioral and ecological traits, arthropod assemblages provide an invaluable source of data for use in monitoring and conserving biological diversity. CTAP not only provides an opportunity to compile new data on Illinois terrestrial arthropod ecology, distribution, and diversity, but it will also serve to demonstrate the value of including data on arthropods in long-term monitoring of the biological and functional diversity of ecosystems in Illinois and elsewhere. CTAP will be the first statewide, long-term conservation monitoring program anywhere in the U.S. to incorporate data on a wide variety of arthropod taxa.

Monitoring of bird populations
D. Niven, S. Bailey, S. Robinson, W. Ruesink
CTAP biologists are monitoring bird populations to develop indicators of forest, wetland, and grassland habitat condition. Indicators include the abundance and diversity of threatened and endangered species, area- sensitive species, Neotropical migrant landbirds, and/or the ratio of cowbirds (brood parasites) to open-cup nesting migrants (host species). For example, the cowbird/host ratio in forests has been shown to strongly correlate with parasitism rates, and is therefore a useful indicator of reproductive success. Because birds are highly mobile, indicators based on bird communities may reflect landscape-level phenomena that extend beyond the boundaries of the habitat patches being investigated.

Vegetation monitoring
D. Niven, C. Dassler, C. Carroll, J. Taft, W. Ruesink, K. Robertson
CTAP vegetation monitoring is being conducted in forest, wetland, and grassland habitats to detect problems of biotic integrity. Processes such as encroachment by invasive and/or exotic species, disease, or altered fire regimes can lead to changes in community structure, the loss of sensitive native plants, and the homogenization of historically diverse plant assemblages. CTAP indicators for plant communities therefore include metrics such as the diversity of native plant species, the percent cover of exotic versus native plants, and the ratio of oaks versus maples in the canopy versus sapling stage. Long-term monitoring of these indicators will reveal spatial as well as temporal patterns of change within these plant communities.

OTHER LONG-TERM MONITORING PROJECTS

Long-term population monitoring of forest birds in the Lake Shelbyville area
S. Robinson, D. Enstrom
In 1997, researchers continued censusing bird populations in three woodlots on the border of Lake Shelbyville in central Illinois for the 13th year. Populations of most species continue to show marked year-to-year variation, but only the Wood Thrush has shown consistent long-term population declines. The data indicate that these populations are being replenished by birds produced elsewhere, quite possibly from forests located more than a hundred miles from Lake Shelbyville given that reproductive success is extremely low in virtually all of the small woodlots available in central Illinois. Censuses conducted in 1998 will allow us to measure the impact of periodical cicadas, which last emerged in the area in 1986, on bird populations.

Mayflies, stoneflies, and caddisflies as indicators of statewide stream health
R. DeWalt
The state's Critical Trends Assessment Project (CTAP) has been designed to monitor changes in ecosystem health throughout the state. Streams are one habitat being sampled. Mayflies, stoneflies, and caddisflies are pollution-sensitive aquatic insects. High species richness indicates good water quality. Illinois knows more about these insects than any other state, largely due to studies conducted by Survey employees before major degradation of the state took place. These insects are being collected from randomly chosen streams throughout Illinois. Monitoring efforts will continue long-term to determine trends, possibly including improvements in species richness due to changes in watershed management practices.

Long-term monitoring of Illinois terrestrial arthropod populations
C. Dietrich, M. Biyal
Arthropods (insects, spiders, and their relatives) are, by far, the most diverse group of terrestrial organisms. Despite their importance to the function of all terrestrial ecosystems (e.g., as pollinators and decomposers), little is known regarding the distribution and abundance of most arthropod species. As part of the Critical Trends Assessment Project, arthropod species richness, composition, and abundance are being monitored at numerous sites throughout the state to gain a better understanding of diversity and conservation status of these organisms. During the 1997 field season, 162 samples composed of about 16,000 specimens and over 1,000 species were collected at 54 sites.

Great Rivers Field Station: a facility for research and education at the Mississippi-Illinois-Missouri rivers confluence area
T. Mihuc, R. Sparks, D. Philipp, S. Robinson, G. Rolfe (University of Illinois)
The goal of this project is to establish a permanent research and education center to improve our basic knowledge and understanding of large floodplain-river ecosystems, which currently are poorly understood and are not managed in a way that will sustain their economic, social, and natural values. In 1997, rented quarters were used for three current program components: the Long Term Resource Monitoring Program, a summer course in field ecology (University of Illinois), and the Region 4 Streams Project (Illinois Department of Natural Resources, IDNR). IDNR has offered a site for a permanent facility in Pere Marquette State Park at the Smith-Duncan historic farm.

Bioresponse monitoring at the Peoria Lake Habitat Rehabilitation and Enhancement Project (HREP)
T. O'Hara, K. Irons, T. Cook, K. Blodgett
The Peoria Lake HREP consists of a mile-long island-windbreak to shelter aquatic plants, a side channel that was opened by dredging, and construction of several moist-soil units to provide waterfowl food. During 1997 researchers sampled fish populations in the area, resurveyed the forested wetland management area, surveyed aquatic plants behind the constructed island, and interpreted aerial photography. While aquatic plants are not growing behind the constructed island as intended, researchers have collected more fish species in the area since the side channel and island were completed.

Long-term resource monitoring (LTRMP)
K. Blodgett, T. Mihuc, R. Sparks
In 1988 the cooperative federal-state LTRMP established five study reaches and stations on the Upper Mississippi River and one reach (La Grange) and station on the Illinois River to monitor and assess long-term trends in the natural resources of the upper Mississippi River system. INHS operates one station on the Illinois at Havana and another on the Mississippi at Alton. Each station uses standardized procedures and equipment to assess status and trends in water quality, fish, vegetation, and macroinvertebrates in their selected river reach, and to determine the causes of the trends.

Ecological accounting of community agricultural systems
R. Herendeen, T. Wildermuth (Natural Resources and Environmental Sciences, UI), D. Onstad, E. Zaborski, A. Winter-Nelson (UI), D. Cavanaugh-Grant (UI)
This project compares energy, nutrient, and resource budgets 1) at the farm level for conventional and organic farms in Illinois and 2) at the community level for the town of Matfield Green, Chase County, KS. Accounting will be framed by three types of indicators: 1) dependence on external inputs and external pollution sinks, 2) disturbance of natural cycles of mature presettlement ecosystems, and 3) depletion of nonrenewable resources. The indicators will be applied to three interconnected types of sustainability: environmental, social, and economic. Comparisons will draw from energy analysis, mass-balance analysis, and economics.

Long-term monitoring in Lake Shelbyville
J. Hoxmeier, D. Wahl
Long-term data collection is important for detecting large-scale temporal trends. In addition, these samples can be valuable for use as pre-data in evaluating the effects of a disturbance. Researchers have been collecting data from Lake Shelbyville since the 1980s and are currently using this data set for answering and developing new research questions. All of the data is collected at fixed sites throughout the lake at regular time intervals. Variables that are being sampled include adult and juvenile fish assemblages, zooplankton, invertebrates, water level, and nutrients. In the future researchers will continue to develop this long-term data set in order to gain a better understanding of the interactions among measured variables and the factors determining community structure in this important reservoir system.

Effects of water quality and water regime on the fish populations of the Illinois River
T. Koel, K. Blodgett, R. Sparks
The Illinois Natural History Survey has sampled fish populations at 26 sites along the Illinois Waterway from 1957 to the present. Researchers are currently describing and analyzing long-term trends in Illinois River fish populations and community structure, and statistically relating changes over time to environmental parameters (chemical and hydrological). Researchers correlate fish populations with timing, magnitude, duration, frequency, and rate of change of floodpulses during critical periods (spawning, overwintering). Water-quality data are incorporated into indices of toxicity for fishes. Results should have implications for ecosystem-based management of water resources to benefit fisheries of the Illinois River.

Watershed Management

Perhaps more than any other ecosystem, the organization and function of running water systems are strongly influenced by the interface of streams and rivers with adjacent ecosystems. Thus, a landscape-level perspective is required to understand the forces shaping the ecology of stream systems. The watershed is the fundamental landscape-level unit for addressing interactions between aquatic and terrestrial ecosystems. A watershed (also called catchment or drainage basin) is the area of land that drains water, sediment, and dissolved materials to a common outlet at some point along a stream channel. A watershed can be defined for any point along a stream channel. Watersheds have a readily visualized hierarchical structure; the drainage basin of a larger river can be considered to be composed of many smaller watersheds.
The watershed is also being recognized as the fundamental spatial unit in the landscape for resource management and planning. This is because the hydrologic and geomorphic effects of both natural and human processes within a watershed are focused at the watershed's outlet. In other words, activities within a watershed are integrated in the stream draining the watershed and, consequently, the stream should be an effective indicator of the watershed's health. An important consequence of taking a watershed-level perspective is that it forces consideration of potential consequences of activities both downstream and upstream of the manipulated area.
Watersheds are composed of three major habitats: stream channels, riparian zones, and uplands. At any point along a stream channel, the riparian zone begins approximately at the average high-water mark of the channel and extends laterally to the edge of the floodplain. A naturally vegetated riparian zone is widely regarded as a critical determinant of the geomorphic, hydrologic, chemical, and biological health of streams. Riparian vegetation is important in many ways to the maintenance of natural stream processes. Riparian forests provide inputs of large woody debris and leaf litter to streams. Woody debris influences channel morphology and hydrology, and provides habitat for organisms. Leaf litter and other organic inputs are important energy sources for stream food webs. Riparian vegetation is also important in mediating water temperature and in moderating the transport of sediment and nutrients from uplands to stream channels. Because of the critical importance of the riparian zone to aquatic and terrestrial ecosystems (e.g., as a source of wildlife habitat), it has been the focus of many watershed management activities. However, it should be noted that the relative importance of activities in uplands and riparian zones to stream processes is a topic of considerable active research.
Although the watershed is the natural landscape unit for directing planning and management of natural resources, management at the watershed scale faces many logistic difficulties. Some of the most significant of these difficulties stem from the fact that the watershed boundaries seldom, if ever, coincide with political boundaries. As a result, a complex network of overlapping and fragmented political jurisdictions governs land management within watersheds, often with little, if any, coordination among governing bodies. In Illinois and elsewhere, citizen groups organized at the watershed level and interested in improving and protecting resource quality with their watersheds may be the best hope for ensuring that planning and management is undertaken with a watershed perspective. The Pilot Watershed Program (run by a consortium including the Illinois Departments of Natural Resources and Agiculture, The Illinois EPA, and the federal National River Conservation Service) is a recent attempt to initiate such an approach to watershed management in Illinois. Its effectiveness will be assessed from a number of perspectives. We will be reporting on the progress of this program in future reports.

STREAM STUDIES

Species-level identification in stream biomonitoring and management
S. Taylor, R. DeWalt
A debate is currently raging concerning the taxonomic level appropriate for biomonitoring of streams throughout the continent. Rapid bioassessment techniques concentrate on genus- and family-level identifications. However, species in the same genus often have very different habitat and food requirements. Are scientists oversimplifying analysis by relying on higher-level taxonomy alone? Researchers are currently using a large data set to evaluate the information content and usefulness of macroinvertebrate data identified to the family, genus, and lower levels of taxonomy. This is the first study of its kind and may provide empirical evidence to support the choice of identification efforts.

Impacts of silt on stream fishes
S. Herrington, L. Page
Increased siltation in streams appears to reduce fish production and diversity, although few studies have attempted to quantify the impact. A study has been initiated to examine the relationship between the amount of silt present and fish diversity and biomass in Illinois streams. The impact of silt on fishes will be examined by looking at taxonomic diversity and at species guilds based on habitat, reproductive requirements, and diet. The study will be conducted in four tributaries of the Embarras River.

Upstream movements of invertebrates
D. Soluk, S. Kohler
Knowledge of movement patterns and dispersal mechanisms is needed to understand the dynamics of natural populations and to predict the recovery of communities from the effects of natural or human disturbance. Research on dispersal in streams has focused mostly on drift and predicts that over the season, upstream areas should be depleted of organisms. Lack of evidence of depletion is explained as a function of recruitment from hyporheic or other areas. An alternative explanation is that organisms may simply travel upstream after drifting downstream for some time. Using innovative technology, researchers are measuring upstream movement and colonization under natural conditions.

Stream habitat assessment using sonar
R. Illyes, S. Kohler, P. Bayley
Assessment of instream physical habitat is often used in conjunction with fish and invertebrate surveys to identify mechanisms responsible for changes in biotic integrity. Such assessments are frequently time-consuming and are difficult to perform in many habitats (e.g., deep or highly turbid areas). Survey researchers are attempting to develop a sonar-based device that will allow rapid and effective quantification of major stream-bottom features under a wide range of physical conditions. Data collected by the device will be downloaded to a computer for storage and analysis.

Sedimentation impacts on streams
S. Kohler, D. Soluk
Land-use practices in watersheds can strongly affect the integrity of stream communities. Army training at Fort Bragg, North Carolina, has involved extensive manipulation of the sandhill landscape. This has produced pronounced increases in soil erosion locally and occasionally over extensive areas within some watersheds. Using unimpacted stream reaches as controls, researchers found substantial sediment-induced alterations in habitat, and associated effects on the diversity and population densities of fish and benthic invertebrates. Research results have been used to develop monitoring protocols for watersheds in this region.

Host-parasite relationships in streams
S. Kohler, M. Wiley (University of Michigan)
The effects of parasites and pathogens on the population dynamics of stream invertebrates and the organization of stream communities has received little study. Recent research indicates that, by suppressing the abundance of key species, pathogens can significantly affect structure and energy flow in food webs. Current research focuses on effects of pathogens on the populations of several species, representing three distinct trophic groups, that are thought to interact strongly with other members of stream food webs. Results to date suggest that pathogens play an important role in the long-term dynamics of at least three species. Future work will attempt to evaluate the ramifications of such effects for other community members.

Structure of stream food webs
S. Kohler, M. Wiley (University of Michigan)
The resilience of ecosystems to major perturbations and the mechanisms determining the biodiversity of communities are fundamental issues in basic and applied ecology. The removal of a dominant competitor from streams over a broad geographic area by a parasitic infection has provided researchers with a unique opportunity to address these issues in otherwise relatively unperturbed systems. Research focuses on how the dominant competitor affects community organization and energy flow, and how the system responds to the competitor's removal and, perhaps, to its eventual recovery to pre-infection levels.

Bioassessment of stream integrity
R. Smoger, S. Kohler, D. Austen (Illinois Department of Natural Resources), B. Hite (Illinois Environmental Protection Agency)
The Index of Biotic Integrity (IBI), a measure of water quality based on fish communities, has been used for over 20 years by state agencies in Illinois and throughout the U.S. to assess stream quality and classify streams. The IBI will be an important component of biological water-quality standards being developed in Illinois. Researchers are refining the IBI for use in Illinois streams by analyzing several aspects of the index, including how components of the IBI vary regionally, identifying reference conditions within regions, the efficacy of IBI components in detecting degraded conditions, and how data from different sampling gears can be combined to estimate fish abundance.

RIVER AND FLOODPLAIN STUDIES

Stable isotope analysis of large-river food webs
B. Herwig, D. Soluk, D. Wahl
Large floodplain rivers contain a mosaic of habitats comprised of both lotic habitats (main channel and side channels) and relatively lentic habitats (backwater lakes, side channels). During flooding periods, the main channel of the river, its floodplain, and backwaters are interconnected. These linkages allow for the exchange of nutrients and organisms among habitats within large-river food webs. Researchers are evaluating the degree to which main channel food webs (invertebrates and fishes) of large rivers depend on allochthonous (floodplain-derived) versus autochthonous sources of organic matter and how this utilization changes seasonally. These linkages will be evaluated using a stable isotope approach where we measure the 13C, 15N, and 34S stable isotope ratios of resources and consumers. Stable isotope ratios in organic matter and animal tissues move through food webs in predictable ways which will allow us to determine the sources of organic matter from which large-river foodwebs derive their energy.

Exploring plankton dynamics in three major habitats of large floodplain rivers
J. Goodrich, J. Dettmers, D. Soluk, D. Wahl
Although off-channel (floodplains, backwaters, and side channels) habitats in large river-floodplain ecosystems are recognized as being important to the riverine plankton community, the role they play in structuring this community is poorly understood. Off-channel habitats can be important nursery grounds for larval and juvenile fishes. Furthermore, these habitats are often thought to be a source of zooplankton and phytoplankton for the main river channel. Researchers have initiated a study of the Illinois and Mississippi rivers to examine how the plankton community differs and to quantify the biotic fluxes of plankton between habitat types.

Indicators of watershed performance
S. Kohler, D. Schneider, J. Braden, D. White, G. McIsaac,
K. McDermaid, J. Vining, R. Cooke, R. Hornbaker
The watershed is recognized increasingly by state and federal agencies as the fundamental spatial unit for natural resource management. Watershed-based management requires a consensus among watershed stakeholders concerning conditions within the watershed, problems to be addressed, and priorities to be assigned to those problems. To aid in the development of such a consensus, researchers are identifying physical, biotic, economic, and social indicators of watershed performance and investigating how they might be used in decision making.

The social context of S.A. Forbes' ecological studies
D. Schneider
In the 1880s, Illinois Natural History Survey scientists began their ecological studies of the Illinois River at the very moment these habitats became the object of social conflict. The studies of the Survey scientists were used to support protection of these habitats from drainage, and Survey scientists became politically active in conservation. Researchers are examining the Forbes papers and INHS archives to document the social basis for these early ecological studies.

Resource conflict in river levee districts
D. Schneider
The floodplain of the Illinois River has been contested terrain since the 19th century as the various interests on the river--farmers, commercial hunters and fishers, private hunting clubs, levee districts, and state agencies, including the Illinois Natural History Survey--struggled to control or protect the natural resources of the river. This project investigates the history of this resource conflict. How the struggle played out at the turn of the century continues to affect the current ecology of the floodplain and its potential for restoration.

Strategic renewal of large floodplain-river ecosystems
J. Braden (University of Illinois), D. Schneider, R. Sparks, M. Demissie (Illinois State Water Survey)
This project takes a multidisciplinary approach to floodplain management options that enhance the overall flow of services from an ecologically diverse and hydrologically open floodplain. The goal is to identify policies that improve the biological diversity and productivity of the floodplain ecosystem without compromising the economic viability of the region. Researchers use an integrated dynamic simulation model composed of three submodels: hydrologic, ecological, and economic. The analysis takes into account both competitive and complementary uses and functions of the floodplain, and it quantifies interactions and feedbacks among system components. The region of analysis is the La Grange Reach of the Illinois River, a part of the Upper Mississippi River Basin.

Understory dynamics in flood-killed forests
A. Plocher
Regeneration following large-scale natural mortality events in floodplain forests is an important but seldom witnessed phenomenon. In this study, four stands with greater than 90% flood-induced overstory mortality, located along the Illinois River near Chandlerville, are being examined. Attempts will be made to relate within and between stand differences in forest regeneration, herbaceous understory dynamics, hydrologic conditions, and preflood forest composition and structure. This work will provide insight on the processes of population dynamics and succession in floodplain forests.

Floodplain forest plant communities and hydrologic regime
A. Plocher
Large midwestern rivers and their associated plant communities have been greatly altered in the last 70 years. The location of floodplain forests at sites on three northwestern Illinois rivers with different hydrologic regimes and with long-term hydrologic records provides a unique research opportunitiy. A study has been initiated that will attempt to relate differences in understory dynamics at sites on the Rock, Spoon, and Illinois rivers to short-term (current) differences in hydrology. Differences in forest structure and overstory composition will be related to long-term hydrologic regime.

Effect of hydrologic alteration on floodplain forest understory dynamics and species composition
A. Plocher
In the midwestern United States stream alteration (levee construction, channelization, agricultural activity) is believed to have had profound effects on floodplain forest communities. On each of two central Illinois rivers, the Sangamon and the Embarras, five floodplain forest sites are being examined to determine whether differences in understory dynamics and species composition can be related to differences in extent of hydrologic disturbance.

Fire and flood: role of disturbance in maintaining biodiversity on floodplains
J. Nelson, R. Sparks
Researchers used the 1817 General Land Office surveys to reconstruct the vegetation pattern in selected floodplains along the Illinois River prior to European settlement. The vegetation pattern and the historical descriptions of surveyors and travelers indicate that both fire and flood were important disturbance mechanisms that maintained a wide diversity of habitats and species. Scientists have also followed the death and regeneration of forests following the 1993 and 1995 floods. The findings of researchers have implications for management practices today. Prescribed flooding and burning could be used to manage for biodiversity on public lands along the Illinois River. Managing disturbance regimes may be more effective and cost efficient than attempts to manage individual species.

Presettlement vegetation patterns along the floodplains of the Mississippi and Illinois rivers
J. Nelson, R. Sparks
Historical data collected by surveyors of the U.S. General Land Office (GLO) in large-river floodplains of the Upper Mississippi River System are being used to measure changes in the natural system due to modern human activities over the past 180+ years. Results along an 80-mile reach of the Mississippi River (Navigation Reaches 25 and 26) indicate that prairie was the dominant plant community on the floodplain in 1816. Savannas and woodlands were also common on the floodplain; dense forests were dominant only on the islands.

Invasive Species

Issues

The first European settlers in North America brought with them several domesticated animals and a variety of plants for food, fiber, garden, and medicinal purposes. They also brought unintended species, such as the house mouse, Norway rat, housefly, and numerous weeds, including dandelions. Over the years, a great number of other non-native species have been brought to this continent from all over the world. Some of these species have been able to reproduce on their own and are thoroughly naturalized.
Exotic, invasive species (EISp) are those organisms that arrive in a new habitat and cause harm to the local flora and fauna. Their populations often increase unchecked because evolved predator/prey relationships were not transferred with them, and hence there are no natural predators or diseases of these species. The kinds and magnitude of threats posed by EISp are numerous and increasing in Illinois. Exotic species have invaded and in the future will invade all types of human-manipulated and natural habitats. In fact, a new invasive species, the Asian longhorned beetle, was discovered in the Chicago area in July. In Illinois, the EISp problem is exacerbated by three significant factors: 1) due to its geographic location and features, Illinois is a prime transportation hub in the U.S., and movement of trade and commercial goods through the state occurs via rail, road, waterway, and air; 2) the already reduced acreage of natural habitats in Illinois makes these areas and the species they contain increasingly threatened and endangered by development and EISp; and 3) although several individual projects address EISp, there is no concerted effort at the state level to bring together a broad array of scientists and habitat managers, representing diverse expertise and perspectives, to address the problems of EISp at an ecosystem level. Although many native species (e.g., white-tailed deer, beaver, black locust trees) also are ecological problems or nuisances in Illinois, those problems have different causes and different solutions.
A vast array of EISp have invaded Illinois habitats--aquatic, terrestrial, agricultural, natural areas, and urban forests. EISp harm Illinois in several ways. EISp compete with native species that are threatened by habitat fragmentation or human-induced disturbance, and thus the added effect of EISp can be severe. Illinois is developed and disturbed more intensively than many other states, thus the threats and pressure from EISp likely are surpassed only in Hawaii and Florida. Deleterious impacts can have environmental, economic, or even human-health costs. For example, exotic weeds that have invaded Illinois threaten the long-term existence and function of forests, prairies, and wetlands, and directly impact plants and animals in these habitats. In agricultural habitats, exotic weed and insect pests cause crop losses, lead to large-scale application of pesticides, and limit commerce via quarantines. Nationwide, annual crop losses from exotic insects exceed $92 billion, and losses from exotic weeds exceed $5 billion. Although quantifying environmental costs of EISp is difficult, EISp devalue natural lands that have been the focus of environmental investment as long-term ecological island habitats in Illinois. Since 1991, the Natural Areas Acquisition Fund has acquired 8,100 acres at a cost of $12 million. The Nature Preserve System in the state protects 35,000 acres, worth over $50 million. In addition, the Illinois Department of Natural Resources owns 400,000 acres of land worth more than $600 million. Finally, several EISp are associated with threats to human health, such as the arboviruses vectored by the Asian tiger mosquito.
Many exotic species occur in Illinois, but not all have become pests or have major impacts. However, once established and spreading, many EISp defy control measures, which are often limited, unavailable, economically inviable, or socially (and environmentally) unacceptable. For example, large-scale use of insecticides throughout northeast Illinois might deter the incipient invasion of gypsy moth, but could harm local insect and bird fauna and would cause an uproar in urban and suburban areas. The spread of aquatic species, such as the round goby, could be curtailed by chemical or electrical barriers, but the costs are potentially great and these barriers could harm other species. Devising intervention measures that are acceptable and cause the least conflict and disruption of economic and environmental systems will be crucial.
Added to the problems of EISp is the lack of concerted measures to access the current status and impacts of EISp, to predict potential EISp, and impose control measures. Different state agencies or entities in a single organization often are unaware of ongoing projects, thus efforts either can be duplicative or at odds with each other. Some EISp problems are due to competing interests: the Ring-neck Pheasant is a valuable game bird but also impacts native ground-nesting grassland birds; exotic fish stocked for fishing or weed control compete with native fish or alter food webs; exotic plants (e.g., Japanese honeysuckle, autumn olive, multiflora rose, crown vetch) promoted for erosion control or wildlife habitat displace native plants.

AGRICULTURAL SPECIES

Cooperative agricultural pest survey
C. Helm, E. Brewer, W. Kirby (University of Illinois), D. Edwards (University of Illinois)
Each year, in cooperation with the U.S. Department of Agriculture's Division of Plant Protection and Quarantine, INHS and University of Illinois scientists conduct statewide surveys for exotic pests of potential concern or pests of known export significance. Recent targets included the pine shoot beetle in Christmas tree plantations and established stands of pines; karnal bunt, a fungus disease of wheat; and the golden nematode in commercial potatoes. This cooperative survey network within and among states generates early detection and distribution information on a variety of agricultural pests with interstate and international significance.

Exotic pest database
E. Brewer, C. Helm
A key component of the Cooperative Agricultural Pest Survey is the National Agricultural Pest Information System (NAPIS), a national database of plant pest survey information. Survey scientists receive and compile data gathered by federal regulatory agencies, the Illinois Department of Agriculture, and in-house cooperators and submit formal data sets to NAPIS for storage and processing. Data includes surveys for exotic pests, pests that may impact export of U.S. agricultural products, releases of biological control agents, and historical records documenting the spread of established pests. Data can be downloaded to produce specialized summary reports and distribution maps.

MOSQUITOES

Studies on the exotic container-breeding mosquito, Aedes albopictus
T. Jensen, R. Novak
Researchers are studying the biology and ecology of the exotic Asian tiger mosquito, Aedes albopictus, in Illinois with the objectives of 1) assessing its importance as a vector of endemic and exotic arboviruses and other mosquito-transmitted disease agents and 2) determining the effect of the presence of Ae. albopictus on the distribution and dynamics of native mosquitoes and other macroinvertebrates developing in natural and artificial water-filled containers.

The infestation of the Asian tiger mosquito, Aedes albopictus, in the Missouri Botanical Garden in St. Louis
R. Novak, R. Lampman, H. Reno, J. McDougal (Missouri Botanical Garden)
In the summer of 1994, the climatron (an indoor area similar to a greenhouse for displaying plants) at the Missouri Botanical Garden in St. Louis became infested with Ae. albopictus, the Asian tiger mosquito. The garden is visited and financially supported by many citizens of Illinois. Ae. albopictus were found in treeholes, bromeliads, and rock pools. Bacillus thuringensis, a bacteria that kills moquito larvae, has been used to control Ae. albopictus in the climatron. Surveillance of the climatron and grounds is an ongoing project.

AQUATIC SPECIES

Taxonomic revision of crayfishes in the Orconectes rusticus family
C. Taylor
The rusty crayfish, Orconectes rusticus, has been introduced into Illinois waters and is rapidly spreading across the northern half of the state. As it spreads, the species is displacing native Illinois crayfishes. A taxonomic study currently under way is examining the evolutionary relationships of the rusty crayfish and its closest relatives. Some of the long-term objectives of this study are to determine the native range of the rusty crayfish and to learn how other species adjacent to the rusty crayfish's native range have persisted.

Establishment of Daphnia lumholtzi in Illinois
S. Chipps, C. Kolar, D. Wahl
The exotic zooplankter Daphnia lumholtzi was recently discovered in Illinois. Studies conducted by INHS scientists have determined that D. lumholtzi has a competitive advantage over native Daphnia spp. by avoiding predation by young bluegill. At present, long-term effects of this exotic species on aquatic ecosystems in Illinois are unknown. To assess potential changes in zooplankton communities, researchers are examining data from Lake Springfield that characterize the lake before and after establishment of D. lumholtzi. In addition, food habits of planktivorous fish are being examined to assess the contribution of D. lumholtzi to fish diets before and after their introduction. Results of these investigations will help quantify changes that have occurred as a result of the establishment of D. lumholtzi in Illinois waters.

Daphnia lumholtzi: an invasive zooplankter in the Illinois River and a potential threat to the Great Lakes
J. Stoeckel, K. Blodgett, R. Sparks
Daphnia lumholtzi originated in southeast Asia and Africa and is now invading the Illinois River. This microcrustacean has exceptionally long spines that defend it against predation by small fish. In the absence of predation, D. lumholtzi may come to dominate zooplankton communities, replacing native zooplankters that are critical food items for the young of most native fishes. The detrimental effects of D. lumholtzi therefore may extend beyond zooplankton communities to fish populations and to ecosystem processes, such as nutrient cycling. Researchers are currently monitoring D. lumholtzi populations along the length of the Illinois River in conjunction with sampling for zebra mussels. Researchers have found D. lumholtzi in the canal systems in Chicago, so it will probably gain access to Lake Michigan and then the rest of the Great Lakes within the next two years.

Gambusia bioenergetic model
S. Chipps, M. Bouchard, D. Wahl
Because mosquitofish, Gambusia affinis, have proved to be so effective at mosquito control, they are now the most widely distributed freshwater fish in the world. Their ability to tolerate a broad range of temperatures, salinities, and dissolved oxygen concentrations, combined with their prolific reproductive strategies, enable them to become easily established in non-native habitats. Their positive influence as a mosquito control agent has been tempered recently by their negative effects on native fishes. To understand the ecological impact of these fishes we must quantify seasonal consumption rates in the field. Development and corroboration of a Gambusia bioenergetic model is a first step to providing a potentially powerful tool to improving management of this species. Physiological data are being collected in the laboratory to parameterize a Gambusia bioenergetics model. Model output will be compared with independently derived field data to evaluate model performance and estimate seasonal energy requirements of a Gambusia population.

Common carp research
J. Parkos, V. Santucci, Jr., D. Wahl
The common carp is an example of an exotic fish that has become established so successfully that its presence is ubiquitous throughout the United States. Even though it is suspected that common carp can maintain shallow lakes as highly turbid systems dominated by algae, little work has been done to evaluate the effects that these fish have on aquatic systems. At the same time, previous efforts to remove these fish have been mostly unsuccessful. This project, in collaboration with the Max McGraw Wildlife Foundation, will quantify the effects that common carp have in aquatic systems and test the effectiveness of a plastic mesh in the mitigation of the environmental damage caused by these fish.

Illinois invasive species management plan
R. Horner (Illinois Department of Natural Resources), R. Sparks
Illinois is developing a state management plan for invasive species for submission to the National Task Force on Nonindigenous Species. Illinois is a key state because the Illinois Waterway provides a man-made connection and invasion route between two of North America's largest drainages: the Mississippi and the Great Lakes-St. Lawrence. The zebra mussel invaded the Mississippi system via the Illinois Waterway, and the Russian round goby is likely to be next. Other invasive species in the Great Lakes that might harm the Mississippi system include the Russian tube-nosed goby, the river ruffe, and the quagga mussel. Invasive species in the Illinois include top-level predatory fish that might deplete an already heavily utilized forage base in Lake Michigan.

Degradation and restoration of Lake Michigan and the Illinois River: past and future of nonindigenous species
D. Lodge (Notre Dame University), D. Schneider (INHS, UIUC),
R. Sparks, J. Marsden (University of Vermont)
The construction of a hydrological connection between the Illinois River basin and Lake Michigan has allowed the spread of nonindigenous species to cross between these systems. Researchers are documenting the history of invasion across this connection and examining the characteristics of the species and ecosystems that make invasion more or less likely to be successful.

ROUND GOBIES

Round gobies in Lake Michigan
D. Soluk, J. Marsden, K. Wolfe
Round gobies invaded Lake St. Clair from eastern Europe in 1990, and had spread to all of the Great Lakes by 1995. The population of gobies in southern Lake Michigan exceeds 40 /m² in places. Researchers are examining the spread of gobies within Lake Michigan, their impact on native benthic fishes, such as sculpins, and their appearance in the diet of sport fish species. We are also tracking the territorial and seasonal movements of gobies using mark-and-recapture techniques.

Potential of round goby to invade streams and rivers in Illinois
D. Soluk, W. Resetarits
The spread of round gobies from the Great Lakes into tributary streams and connected watersheds (especially the Mississippi River system) should be a focus of great concern. Preliminary experimental studies of growth and thermal tolerance indicate a potential to occupy both cold-water and warm-water stream systems throughout most of North America. Ongoing studies suggest potential impact of round gobies on streams is high, especially for populations of other smaller benthic fishes (e.g., darters) that may be displaced or directly consumed by gobies. Researchers are focusing on quantifying the current range of goby in the canals that connect the upper Illinois River with Lake Michigan, and on providing an assessment of the potential final range and impact of gobies on habitats outside of the Great Lakes.

ZEBRA MUSSELS

Determining zebra mussel metabolic rates
S. Madon, D. Schneider, J. Stoeckel, R. Sparks
Measurements of metabolic rate are vital to studies on energetics and functional responses of zebra mussels to environmental variables. However, laboratory estimates of metabolic rate often fail to reflect metabolic costs in natural systems. The electron transport system (ETS) enzyme assay provides a method for measuring metabolic rates in zebra mussels in rivers. Zebra mussel respiration has been calibrated with ETS activity in the laboratory. Researchers are now employing this technique to determine metabolic rates and oxygen demand of zebra mussel populations in the Illinois River.

Zebra mussel (Dreissena polymorpha) seasonal dynamics in large floodplain rivers
T. Mihuc
Current research emphasizes habitat requirements and seasonal patterns in zebra mussel colonization in Neotropical and temperate large floodplain rivers in North America. Temperature and dissolved oxygen tolerances may inhibit the establishment of permanent populations laterally into floodplain habitat in many rivers, particularly at the southern periphery of the current invasion where tolerances are often exceeded during summer months. The resulting pattern follows seasonal patterns in temperature and dissolved oxygen levels with colonization during late fall and a summer die-off throughout the floodplain.

Metapopulation modeling of zebra mussels
D. Schneider, J. Stoeckel, D. Blodgett, R. Sparks
Populations of zebra mussels in the Illinois River may be maintained in the face of suboptimal conditions in the river by continued immigration from Lake Michigan. Researchers are developing a metapopulation model of the zebra mussel in the Illinois River, based on immigration of larvae from Lake Michigan, to predict the variability of mussel populations in the river and to search for critical opportunities for control.

Predicting the spread of the zebra mussel and its risk to native mussel communities
D. Schneider, C. Ellis, K. Cummings
INHS researchers are using data on boat traffic in Illinois lakes and rivers to develop a probabilistic model of zebra mussel spread in Illinois. This will be coupled in a geographic information system with collections records for native mussels to predict communities of native mussels at greatest risk from the zebra mussel. Central Illinois reservoirs act as stepping stones for invasion of biologically important streams.

Zebra mussel growth in the Illinois River
D. Schneider, R. Sparks, J. Stoeckel, S. Madon
Researchers are measuring growth of individually marked zebra mussels in various habitats in the Illinois River floodplain ecosystem to evaluate the role of temperature, sediment, and body size in zebra mussel growth. Measured growth rates will be used to calibrate an energetic model. Also being evaluated are the effects of natural and artificial suspended sediment on the energetics budget of the zebra mussel. These data will be used to develop a predictive model of zebra mussel growth in turbid river ecosystems.

Integrated Pest Management

Issues

For well over a century, humans have used a great number of approaches to help alleviate pest problems with insects, mites, plant-parasitic nematodes, bacterial, fungal, and viral plant pathogens, weeds, and vertebrate animals. However, no approach has been more popular and successful than integrated pest management (IPM). Conceived 25 years ago, IPM grew out of discontent with the nearly exclusive chemical approach to pest control in the 1950s. Indiscriminate use of broadly toxic and persistent insecticides resulted in the mortality of pests' natural enemies and other nontarget organisms, and contamination of the environment with pesticide residues. Some of these insecticides gradually lost effectiveness because the few individuals that happened to be genetically resistant to them survived and reproduced, and soon the whole population possessed the same resistance. Freed from their natural enemies, pest populations could resurge and reach even higher densities than before pesticide treatment. Probably the greatest percentage of pest problems are encountered in agricultural production systems where vast monocultures of susceptible hosts are grown in a given area. Here a change in weather or crop production practices can trigger a rapid increase in a pest's population density.
The primary goal of IPM is to reduce losses from pests in ways that are not only effective but also economically sound, and environmentally compatible. Long-term solutions to problems rather than just short-term protection from pests is an important goal of IPM; reducing or modifying the impact of pests and reducing injury to tolerable levels is of greater concern than simply killing pests.
Although IPM is often associated with crop protection, the scope of IPM is much broader, encompassing pest problems with livestock and pets, urban dwellings, ornamental plants, and pests of medical importance to man, such as mosquitoes and ticks, which may cause discomfort and act as vectors of human disease. With IPM, several techniques are often used simultaneously to solve a specific pest problem. For example, a pest management program may employ the use of natural enemies, resistant varieties, crop rotation, tillage, sanitation, and other technological advancements to keep pest populations below levels that cause economic damage (economic threshold). Although pesticides may be utilized in some specific cases, users of the IPM approach weigh the needs and alternatives to these chemicals before choosing an approach. To use these tools effectively, IPM depends on a correct identification of the pest that is causing the problem and a thorough understanding of the pest's biology and its relationship to the host and the environment. IPM also requires an assessment of pest status, which is usually determined by sampling (scouting) for pests and measuring levels of pest injury.
In developed countries, IPM has become the pest control strategy of choice for agricultural pests. In 1993, the Clinton administration called for its adoption on 75% of U.S. farmland by the year 2000.

Ongoing Projects

IPM and the pest situation are constantly changing. Active research programs are essential in improving current IPM systems and to solve new problems as they arise. The western corn rootworm is a case in point. The corn-soybean-corn-soybean rotation has been exceedingly effective in preventing western corn rootworm injury to corn without the need to use a soil insecticide. As long as corn was not planted following another crop of corn, no soil insecticide was needed to control western corn rootworms. Until recently, western corn rootworm beetles laid their eggs exclusively in cornfields. Since rootworm larvae could survive only on the roots of corn when they emerged from eggs the following spring, planting soybeans in an egg-infested field broke the rootworm life cycle. Likewise, corn planted after soybeans contained few eggs and no insecticide was needed to protect the crop from rootworms. Simply rotating crops formed the basis of a very simple but effective IPM system for managing corn rootworms. However, all that changed in 1993 when Survey scientists discovered that western corn rootworms were beginning to lay eggs in soybean fields. By 1995, widespread injury to rotated corn in nine east-central Illinois counties forced many corn producers to use a soil insecticide on their first-year corn acreage for the first time. In response to this change in egg-laying behavior, Illinois researchers developed sampling procedures (yellow sticky traps) and a preliminary economic threshold for western corn rootworm beetles in soybean fields. This will allow farmers to make informed decisions on the need for a soil insecticide in first-year corn on a field-by-field basis. Fields with fewer than the threshold number of beetles (seven beetles per trap per day) would not need to be treated with a soil insecticide when rotated back to corn the following spring.
Many other research projects of Survey scientists involve the development and refinement of IPM strategies to manage pest species. Examples of these include strip tillage and intercropping to improve vegetable production; evaluation of microbial pesticides, plant-based insecticides, resistant or tolerant crop varieties, and genetically engineered crops against major insect pests; refinement of pest development models, pest sampling procedures, and economic thresholds so that pesticide applications can be eliminated, reduced, or targeted more precisely; using natural enemies to control serious weeds such as purple loosestrife; and developing resistance management strategies to preserve the life span of newly developed genetically engineered crops such as Bt corn for European corn borers.

CROP PESTS

Aphid vectors in sweet peppers
D. Voegtlin
Sweet pepper cultivation in southern Illinois has been threatened over the past several years by major crop failures caused by cucumber mosaic virus (CMV). Aphids are the only known vectors of this virus. During the past two years thousands of aphids flying in pepper fields have been collected. Over 75 species were identified from these collections; of these, 17 are known to transmit CMV to peppers. To date, none of the species tested have been implicated as vectors in southern Illinois. Further work will be undertaken to ascertain which species are responsible for spreading the crop-destroying virus.

Impact of redroot pigweed on yield and insect pests of snap (green) bean
H. Bottenberg, J. Masiunas (University of Illinois), C. Eastman
Economic thresholds for control of specific weeds are needed for Illinois vegetables so that control measures are applied only to avoid serious yield losses. Plans for weed management, however, could affect management of insect pests. The objective of researchers was to determine the effect of density and time of emergence of redroot pigweed on snap bean yield and populations of the potato leafhopper. In 1997, pigweed populations did not significantly affect leafhopper numbers. Also, densities of 0.5 to 1.0 pigweed/meter did not significantly reduce bean yields. This study will be continued to evaluate these encouraging results under different growing conditions.

Strip-tillage effects on snap beans grown in cover crop mulch
H. Bottenberg, J. Masiunas (University of Illinois), C. Eastman
In continuing studies with vegetables grown in cover crop mulches, yields of snap bean planted into strip-tilled rye mulch were closer to those achieved with conventional tillage (no mulch) than in 1996. Yields were still lowest with plants seeded into solid rye mulch. Potato leafhopper populations and leaf nitrogen levels were higher in plots with conventional tillage than in plots with rye mulch, but only early season. Damage by leaf-feeding beetles did not differ significantly among treatments. Further improvements in strip-tillage mulch systems are needed to make this alternative weed management technique more competitive with conventional practices.

New sources of insect resistance in soybeans
C. Helm, R. Nelson (University of Illinois), R. Hammond (Ohio State University)
Because of the narrow genetic base currently in use in the development of insect-resistant soybeans, breeders and entomologists have continued to search for new sources of resistance. Over 700 new accessions from central China were evaluated over a three-year period for resistance to leaf-feeding insects in Illinois and Ohio. Although moderate levels of resistance were detected in five lines, none expressed levels of resistance similar to two currently available sources. However, plant breeders feel these lines may have the potential to contribute to improved insect resistance by genetically combining them with the two most frequently used sources.

Insecticide evaluation of field, forage, fruit, and vegetable crops
J. Shaw, M. Gray, K. Steffey, R.Weinzierl
Field trials were conducted to provide an impartial evaluation of chemical and biological pesticides applied, against the major insect pests, to a variety of field, forage, fruit, and vegetable crops at several locations in Illinois. Resistant or tolerant crop varieties and genetically engineered corn varieties were assessed for efficacy of major insect pests of their respective crops. All trials generated meaningful data to support current IPM recommendations and the development of new IPM approaches. These trials utilized 70 different products and were conducted on six agricultural commodities encompassing 24 Illinois agrobusiness industries.

Biota movement and dispersal data Web site
G. Kampmeier, S. Isard (University of Illinois), M. Irwin
The movement of allergens, pests, and other biota in the atmosphere influences our health, environment, and agricultural productivity. These biota rely on atmospheric processes for dispersal and the impact of this dispersal involves the activity of biologists, biometeorologists, radar specialists, and physicians. The Web site <http://www.inhs.uiuc.edu/cee/wwwtest/movement/migr_dis.html> helps coordinate and disseminate research activities and results in this multidisciplinary area. The site was begun for NCR-148, Migration and Dispersal of Insects and Other Biota (the authors represent Illinois on this committee), and encompasses many other movement and dispersal-related organizations and activities worldwide.

Aphid attraction and preference for plants infected with SMV
A. Fereres (Visiting Scientist, University of Illinois), G. Kampmeier,
M. Irwin
The progress of nonpersistently transmitted virus epidemics can be substantially altered by the degree of aphid attraction or preference for virus-infected plants. Researchers examined color- and odor-mediated attraction of aphids to infected plants, which often appear yellowish to human eyes. Myzus persicae and Rhopalosiphum maidis preferred alighting on yellow rather than green (plantlike) or brown (soil-like) ceramic tiles, but expressed no preference for leaves infected with soybean mosaic virus (SMV) or for chlorophyll-deficient soybean leaves. Neither species showed any odor-mediated attraction to leaf extracts of SMV-infected leaves. R. maidis remained longer on uninfected than on SMV-infected soybeans before taking flight.

A molecular marker for pathogen identification
W. Chen
The soybean brown stem rot disease is caused by the fungal pathogen Phialophora gregata. The fungus has two morphologically identical pathogenic forms, one causing the disease on soybean and the other on adzuki bean. Separating the two forms is difficult and requires time-consuming pathogenicity tests. Mycologists at the Survey in cooperation with plant pathologists at the USDA-Urbana and the University of Wisconsin have identified a molecular marker that can be used to reliably facilitate separation of the two forms. The marker utilizes the presence of an intron of the nuclear rDNA of the adzuki bean pathogen.

BIOLOGICAL CONTROL

Biology and foraging behavior of a diamondback moth parasitoid
A. Gonzalez (University of Illinois), C. Eastman
Diadegma insulare was the most abundant parasitoid of diamondback moths in field studies reported last year. In laboratory studies, D. insulare longevity and fecundity were much greater when adults were fed honey rather than starved. Parasitoid larval survival and adult size were greatest when parasitoid eggs were laid in second-instar diamondback larvae rather than in older instars. When foraging D. insulare were present, diamondback larvae used evasive behavior and consequently had greater inter- and intraplant movement than in parasitoid-free environments. These findings define conditions needed for effectiveness of D. insulare as a biological control agent for diamondback moth.

Habitat specificity of Cotesia spp. parasites
R. Wiedenmann, C. Rutledge
Researchers are assessing the habitat specificity of several parasitic wasps used for biological control of stemborer pests. Parasitic insects respond to cues from the habitat, then find hosts in the habitat. Three species of Cotesia wasps respond differently to odors from different grasses but show little response to nongrasses. Further, these wasps did not learn new preferences. This means the parasites have an affinity for grass habitats (e.g., corn, sorghum), but will not choose nongrass habitats. This degree of habitat specificity helps ensure that the parasites will have little chance to harm nontarget species.

Physiological host-parasite interactions
R. Wiedenmann, M. Alleyne
Successful use of parasitic insects for biological control requires that the parasites are physiologically compatible with their hosts. The level of compatibility also determines the physiological host range of the parasites, thus their specificity. Three Cotesia species show different levels of compatibility with related stemborer hosts. The main host defense, the immune response, is overcome to different degrees by each parasite species. The differences in host compatibility suggest these parasites will have a narrow host range and have little impact on nontarget species, but explicit testing will be needed to assure safe use of these parasites.

Biological control in home gardens and landscapes
R. Wiedenmann, A. Wegeng
In this new collaborative project with Purdue University, INHS staff are training master gardeners in Illinois and Indiana about biological control and using it in their home gardens and landscapes. In addition, staff are supervising gardeners that are conducting three research projects in their gardens. They are releasing Trichogramma wasps twice weekly against imported cabbage worm; using mulch in potato plots to see how it affects predatory ground beetles and their predation; and spraying sugar-water solutions on tomatoes to see how they attract predators and parasites to the plants. Each study has some gardeners using test treatments, others are controls.

Insect pathogen interactions
L. Solter, D. Pilarska (Bulgarian Academy of Sciences)
The population dynamics of most insect species are strongly influenced by pathogens. The interactions of different pathogen species in a single host or host population can influence the effects of each pathogen on the host population. A single insect species can host several species of microsporidia, a group of entomopathogens in the protistan group, but usually only one species of microsporidia is present in a local host population. Laboratory studies are under way to determine how different combinations of microsporidian species isolated from the gypsy moth, Lymantria dispar, interact in a single host individual.

New technology for studies of microsporidia
M. Venditti (University of Illinois), L. Solter
Microsporidia, important unicellular pathogens of arthropods, are extremely difficult to identify to species because the infective spores of different species are morphologically similar. This situation complicates studies of microsporidia in the field, both for studies of natural infections and for biological control programs. A relatively new molecular technique, random amplification of polymorphic DNA by polymerase chain reaction (RAPD-PCR), is being tested for use as a tool to distinguish between closely related microsporidian species.

Host specificity of insect pathogens
L. Solter, J. Maddox
Most experiments designed to test the host specificity of insect pathogens are conducted in a laboratory setting and, therefore, test the physiological host range of the pathogens but not the host range in the field, the ecological or realized host range. Laboratory studies, which are necessary before release of exotic pathogens into the environment for purposes of biological control, were designed to reflect the host specificity in the field as closely as possible. The capability of these experiments to predict ecological host range is being evaluated in field studies of the pathogens in the area of origin of the host.

Biological control of purple loosestrife
R. Wiedenmann, D. Voegtlin, S. Post, A. Wegeng
Researchers raised and released two species of Galerucella leaf-feeding beetles against purple loosestrife throughout Illinois wetlands. In 1997, our staff shipped nearly 400,000 adult beetles to cooperators for release in approximately 50 wetland sites. Further, cooperators raised over 100,000 beetles at their own sites. The first signs of success are appearing at two sites. Near Illinois Beach State Park, beetle feeding reduced loosestrife flowering to less than 5% of plants, and weed densities are reduced. In Savanna, large numbers of Galerucella greatly damaged the loosestrife infestation, with hundreds of dead and stressed plants.

CORN ROOTWORM ECOLOGY

Survey of rootworms in Illinois soybeans
E. Levine, J. Spencer, S. Isard (University of Illinois)
The density of western corn rootworm (WCR) beetles in 72 soybean fields in 29 Illinois counties was measured with a sweep net from late July through August 1997. Beetles were most abundant in the 10-county east-central portion of Illinois where egg-laying in soybeans has resulted in rootworm injury to corn planted after soybeans. WCR abundance declined with increasing distance from known sites of infestation. In general, few WCR were found in soybeans west of Illinois Highway 29, north of U.S. Highway 30, or south of an arc drawn from Decatur through Charleston to the Wabash River.

Assay for egg-laying behavior in the western corn rootworm (WCR)
M. Vodkin, K. Ramsdell, E. Levine, R. Novak
Within the last four years increasing numbers of farmers in east-central Illinois who annually rotate corn have experienced problems with injury from the WCR. The evidence suggests that the WCR has overcome crop rotation by laying eggs in soybean fields. In order to monitor the scope of the problem prior to planting and identify fields or areas at risk, a molecular assay has been developed. Four oligonucleotides have been identified that distinguish WCR found only in problem areas. Further tests are ongoing to determine whether this particular assay will be predictive.

Spread of rootworms infesting soybean
D. Onstad, M. Joselyn, S. Isard (University of Illinois), E. Levine, J. Spencer
A computer simulation model was created using meteorological and biological data to forecast the spread of western corn rootworm (WCR) beetles that lay eggs in soybean fields, thus circumventing crop rotation as a management practice. The model predicted that these "problem" WCR would spread at a rate of 10-30 km per year depending on the direction of prevailing storms and winds. "Problem" WCR are expected to be laying their eggs in soybean fields in much of Ohio, lower Michigan, and southern Wisconsin during the next 5 years, while "problem" WCR should reach Iowa within the next 10 years.

Soybean yield: effect of rootworm feeding
E. Levine, J. Spencer
Researchers have observed repeatedly that western corn rootworm (WCR) beetles readily devour soybean flowers. Although soybean flowers self-pollinate before the blossoms open, researchers decided to take a closer look at the effect of this feeding on soybean seed production. A preliminary study in 1996 indicated a small negative (a statistically insignificant 6.1% yield loss) impact on yield. The study was repeated in 1997 with greater replication. Again, we detected no significant effect of WCR feeding on blossoms on soybean yield. If this feeding is having an impact on yield, it is probably very subtle.

Survival of rootworm larvae on soybean roots
E. Levine, J. Spencer
Repeated attempts to rear western corn rootworm (WCR) larvae on soybean roots have been unsuccessful. Scientists are confident that the WCR adults that they find in soybean fields must have flown there from neighboring cornfields. The fact that researchers capture WCR beetles in vial traps about a week sooner in corn than in soybeans is a further indication that the beetles fly into soybean fields from nearby cornfields. The skewed mid-season sex ratio that researchers find in soybean fields (about 70% female) also points toward immigration of beetles (more females than males colonize new fields).

Rootworm food choices
J. Spencer, E. Levine
Western corn rootworm (WCR) beetles, collected where injury to corn planted after soybeans was common, were dissected to determine their food choices. During late July and early August 1997, WCR collected in soybean fields were eating a mixed diet of corn and soybeans (approximately 30% corn and 40% soybeans). By mid-August, the frequency of soybean foliage feeding rose to 85-100%. Pollen from various weed species was also commonly found in the beetles during this time. Researchers have found that diet mixing is necessary because soybeans alone will not support beetle maintenance or egg development.

Daily rootworm flight patterns
J. Spencer, S. Isard (University of Illinois), E. Levine
A daily rhythm of western corn rootworm (WCR) immigration to and emigration from soybean fields was discovered; this has important implications on the timing of population censuses. Between 7:00 and 11:00 a.m. immigration exceeded emigration. Flight activity peaked between 11:00 a.m. and 1:00 p.m., with emigration exceeding immigration, and WCR abundance in soybeans reaching a minimum. By 5:00 p.m., more WCR were again flying into the field than leaving, and WCR abundance reached a maximum just before sunset. Beetles did not fly between sunset and sunrise, remaining in the soybean field overnight.

Influence of weather on rootworm flight
S. Isard (University of Illinois), J. Spencer, E. Levine
Micrometeorological measurements in soybeans identified weather conditions that modify seasonal and daily patterns of western corn rootworm (WCR) movement. Air temperatures below 15deg.C or above 31deg.C and wind speeds in excess of 2.0 meters per second prohibit WCR flight and occur frequently during the growing season in east-central Illinois. Researchers' data indicate that the weather during only 60% of the daylight 10-minute measurement intervals in August 1997 was conducive to WCR flight, and that for approximately one-third of the days in the month, atmospheric conditions substantially reduced interfield movement for the entire daylight period.

Rootworm activity outside of corn and soybeans
E. Levine, J. Spencer
Alfalfa and red clover fields were sampled for western corn rootworm (WCR) beetles in east-central Illinois, where WCR injury to corn planted after soybeans is prevalent. High densities of WCR beetles were present in all four crops during the summer and large numbers of eggs were recovered in the three crops that were sampled (corn, soybeans, and alfalfa). WCR beetles were also observed feeding on velvet leaf, giant ragweed, and Jerusalem artichoke adjacent to corn plants on which other WCR beetles were feeding. WCR adult feeding and egg-laying preferences are now broader than what has been previously reported.

Medical Entomology

The Medical Entomology Program was created by the Illinois Natural History Survey within the Center for Economic Entomology as a result of the 1989 Illinois Waste Tire Act. The Illinois General Assembly determined that used and waste tire accumulations pose a threat to public health, safety, and welfare by providing a habitat for five species of Illinois mosquito capable of transmitting pathogens to man and animals. Additionally, used tires also provided the means of introducing, spreading, and finally establishing the Asian tiger mosquito as well as other exotic mosquito species that were able to adversely affect man and domestic and wild animals. Based on the significance of the invasion of the Asian tiger mosquito and the recurring threat of long-time resident disease-carrying mosquito species in tires, the Survey, through the Medical Entomology Program, was mandated to perform research to study the biology, distribution, population ecology, arbovirology, and biosystematics of tire-inhabiting arthropods, especially mosquitoes.
The complexity of the legislative biological mandate required the assembly of a multi-disciplinary team of scientists to concentrate their research efforts in several different specialties. The principal research objectives are to 1) study and provide statewide scientific data on mosquito-borne diseases related to those mosquito species complexes found in used tires, 2) develop and implement environmentally safe and effective mosquito control techniques and tactics, 3) investigate the impact of domestic and exotic mosquitoes and other medically important arthropods found in tires in Illinois ecosystems, and 4) develop new techniques and methods to monitor, collect, and identify mosquitoes and related mosquito-borne pathogens.
During the course of the Medical Entomology Program we have accomplished several major tasks that are related to our objectives. Using molecular technology we have developed a method for virus detection and identification that has greater sensitivity than current technology. This has allowed our research to focus on virus detection using mosquitoes instead of birds and other mammals that may be injured when blood is drawn for virus isolation. This detection method also allows us to detect very small amounts of virus, thus providing us with a tool to do in-depth studies of the natural history of mosquito-borne viruses. Our research also developed the use of corncob granules as insecticidal carriers for treating used tires. A joint study with the Illinois Soybean Program Operating Board is leading to the development of a new class of insecticides that will be environmentally safe and effective. Soybean oils are also being studied as carriers for a variety of microbial insecticides that are generally lost in the environment once they sink to the bottom of a mosquito larval aquatic habitat. Additionally, the Medical Entomology Program has monitored the spread of the Asian tiger mosquito in Illinois, tested genetic methods to manage this species by replacing the gene(s) that control winter survival, developed new methods to sample this daytime exotic mosquito, and shown that the eggs of this species as well as other tire-inhabiting mosquitoes survive the tire shredding process.
The ultimate goal of the Medical Entomology Program is to develop and test through applied research new environmentally friendly, economically sound and effective methods to prevent mosquito-borne diseases and manage mosquito pests in Illinois. Although the program has accomplished several major scientific tasks, the research needs established by the Illinois Waste Tire Act still present major challenges for the INHS and the Medical Entomology Program.

Medical Entomology Projects

Integrated mosquito management: Champaign-Urbana encephalitis prevention program (CUEPP)
R. Novak, M. Slamecka
The CUEPP is a seasonal program funded jointly by the cities of Champaign and Urbana, the village of Savoy, and the University of Illinois. The CUEPP mandate is to minimize the spread of mosquito-borne encephalitis. Target mosquito species are Culex pipiens and Aedes triseriatus. Surveillance of the Asian tiger mosquito is also a priority of the program. Management is accomplished through source reduction, insecticides, and public education. The focus of control is on the larval mosquito populations found in roadside ditches, street catch basins, and artificial containers (e.g., used tires). Resident complaints are also investigated and managed where feasible.

Evaluation of gravid traps as Culexsp. (Diptera: Culicidae) oviposition monitors in a virus prevention program
T. Schaub, H. Reno, R. Novak
Monitoring oviposition of Culex pipiens, the Midwest's primary vector of St. Louis encephalitis (SLE) virus, and Cx. restuans, the presumed amplification vector of SLE in birds, is important to central Illinois' SLE prevention programs. An efficient method of monitoring species' relative abundance and viral prevalence would be ideal but has been problematic since adult identification is difficult. In this study, Center for Disease Control gravid traps were used to collect adults, which were differentiated using primers to amplify rDNA genes. Prevalence was compared with the traditional method of oviposition traps. Results indicate an earlier Cx. pipiens peak with gravid traps.

Soy oil derivatives as mosquito larvicides
R. Lampman, U. Eckenbach (University of Illinois), R. Novak, D. Seigler (University of Illinois)
The Illinois Soybean Program Operating Board has provided funds for developing environmentally safe soy-based insecticides for mosquitoes. Laboratory tests have demonstrated that formulations of methylated soy oil (MSO) with small amounts of specific surfactants are effective control agents for larvae and pupae of several mosquito species, including vectors of St. Louis encephalitis (Culex species) and human malaria (Anopheles species). The MSO mixture forms a thin layer on the water surface and suffocates the immature mosquitoes by coating the trachea with oil. Mixtures of these products with other mosquitocidal products is being investigated.

Using corncob granules to control insect pests
R. Metcalf (University of Illinois), R. Novak, R. Lampman
By coating corncob granules with a bacterium producing a mosquito-specific toxin, an environmentally safe product was developed for mosquito control that could be easily dispersed in tire piles and overhanging vegetation in wetland habitats. The granular technology also has great potential for suppressing adult corn rootworm populations by combining rootworm feeding stimulants, volatile attractants, and insecticides with corn granules. Recent field tests indicate these granular formulations can lure beetles to the edges of treated cornfields. The dispersal of the bait throughout corn plots actually disrupted the ability of males to find mates.

Natural product mosquito larvicides
U. Eckenbach (University of Illinois), R. Lampman, D. Seigler (University of Illinois), R. Novak
Natural selection has resulted in a vast chemical arsenal within the plant kingdom in response to vertebrate and invertebrate herbivores, as well as protection against attack by bacteria and fungi. Many of these natural products have insecticidal activity, such as pyrethrins, rotenoids, nicitinoids, sabidilla alkaloids, azidirachtin, and so on. Researchers have tested extracts from almost 200 plant species for toxicity to mosquito larvae and found about 2% of the extracts are toxic at dosages well below 50 parts per million. Two plants with high activity were honewort and prickly ash with the active principles being polyacetylenes and pyranocoumarins, respectively.

Spore-forming bacteria in mosquito habitats in Illinois
J. Siegel, R. Novak, A.R. Smith (University of Illinois)
The purpose of this project was to identify mosquito pathogens in waste-tire dumps and other wetland areas. Water and soil samples were collected from tire dumps and standing water throughout Illinois. Spore-forming bacteria were cultured from the samples and identified by gas liquid chromatography. A catalog of species is being compiled that will provide important baseline information on potential food sources for mosquitoes as well as pathogens. This project is in the final stages of completion.

Identification of microbial insecticides
J. Siegel, A.R. Smith (University of Illinois), R. Novak
Cellular fatty acid profiles have been created for microbial insecticides used in vector control and in agriculture, specifically Bacillus thuringiensis serovars aizawai, kurstaki, and israelensis. as well as a new mosquito larvicide, Bacillus sphaericus. These profiles are an essential tool for determining whether bacteria with mosquito activity that researchers discover are indigenous or commercially produced. This investigation determined the length of persistence of commercial microbial insecticides in tires and other containers. This study has been completed and submitted for publication.

Efficacy of current tire treatments
J. Siegel, R. Novak, R. Cieslik, J. Clarke III (Clarke Environmental)
One of the concerns in any tire treatment scheme is what percentage of the pesticide applied reaches the tires. With cooperators from the Chicago Department of Health and Clarke Outdoor Spray Company, a tire yard in Chicago was treated with blank granules. The number of granules per tire was counted and percent coverage calculated. Three tire stacking methods were evaluated: random, shingle-stacked, and column-stacked. Granule penetration was highest in the random-stacked piles and lowest in column-stacked tire piles. Between 10% and 20% of the granules actually reached their target. This study has been completed and published.

Determining the host range of a new Bacillus sphaericus mosquito larvicide
J. Siegel, R. Novak
The host range of a new microbial larvicide, Bacillus sphaericus, was investigated in a series of experiments conducted in the laboratory and field. Laboratory studies determined the susceptibility of the Eastern treehole mosquito, Aedes triseriatus, vector of LaCrosse encephalitis, and Anopheles punctipennis, a malaria vector, to this product. The laboratory data will be validated in a series of field experiments looking at the efficacy of this product in waste tires and drainage ditches.

Mosquitoes of Illinois: an update on their distribution, ecology, and biology
T. Jensen, R. Novak
Researchers are collecting and identifying the mosquitoes occurring in different habitats and regions of Illinois, including data on mosquito biology, ecology, and temporal and spatial distribution. This baseline data will be used to assess the effect of changes in land and water use practices and climatic changes on the Illinois mosquito fauna. A result of these studies is that we have collected Culiseta impatiens, a species hitherto unreported from Illinois, occurring in Champaign County.

The effects of enhanced UVB light on mosquito larval development
E. Kennedy, N. Krasavin, R. Novak
The effects of UVB light on mosquito biology are largely unreported. Survey scientists studied the effects of enhanced UVB on mosquito larval development. A positive correlation between larval survival and light intensity and duration, developmental stage irradiated, and species was found. Researchers apply these results to the distribution of mosquito species and consider how this distribution may change with changing climate and mosquito survival.

Anopheline mosquitoes of Illinois
T. Jensen, R. Novak
Our knowledge of the Anopheles mosquitoes of North America has changed dramatically in recent years with the recognition that many of our most important biting pests and historic vectors of malaria (including those in Illinois) are complexes of morphologically but genetically distinct species. In this study researchers are obtaining ecological, biological, and genetic information on the Anopheles mosquitoes in Illinois to determine which species are present in the state, where they occur, and which populations are likely to be important as biting pests and could participate in the transmission of introduced malaria.

Ecology of Aedes triseriatus and Aedes hendersoni
H. Reno, R. Novak
The mosquito vector of LaCrosse virus (LACV), Aedes triseriatus, and its nonvector sibling species, Aedes hendersoni, provide a model to study the evolution of vector-virus relationships. Field studies examine urban and rural distribution of these mosquitoes as well as their blood-feeding habits. Studies examining the salivary gland protein apyrase are also in progress. Apyrase is responsible for interfering with platelet aggregation in the blood-meal host. Salivary glands from Ae. triseriatus and Ae. hendersoni are removed, described morphologically, and apyrase activity characterized. Comparisons between sibling species will begin to address the evolutionary issues surrounding blood feeding and LAC virus-vector relationship.

Culex pipiens overwintering
K. McClellan, R. Novak
Adult female Culex mosquitoes spend the winter in protected sites, such as mines, cellars, subway passages, basements, culverts, tunnels, and rodent burrows. Researchers have been studying the Culex population changes in a storm-water drainage tunnel in Champaign. Using PCR, a DNA analysis technique, it was found that Culex pipiens is the only Culex overwintering in the tunnel. The Culex pipiensadults enter the tunnel in the autumn through several openings, and most of them stay within 40 meters of the opening. Some temporarily leave the tunnel on warm days during the winter.

The dispersal of Aedes albopictus in Illinois
R. Lampman, R. Novak, P. Purseglove (Illinois EPA)
Although several major tire sites are undergoing clean-up, little is known about whether this will limit the spread of Ae. albopictus. The Asian tiger mosquito is both a potential vector of several arboviruses and a major nuisance pest. Survey researchers recovered this species from sod-baited gravid traps at seven test sites in southern Illinois. Five of these test areas (Newton, East St. Louis, Mounds, Ullin, and Campbell Hill) were within 0.5-1.0 km of a waste-tire site, whereas the other positive areas (Red Bud and Steeleville) did not have obvious tire sources. This is an ongoing project.

Preliminary studies for St. Louis encephalitis virus (SLEV) in Culex salinarius
M. Vodkin, J. Olson, R. Novak
The role of Cx. salinarius in maintaining the enzootic cycle of SLEV has been debated. Areas of south Texas are known to have an enzootic cycle as well as this mosquito species. This species also occurs throughout Illinois. A modest number of mosquito pools of that species were collected early in the season, during low mosquito population size. These samples, along with the appropriate standards, were analyzed for SLEV presence by the reverse transcriptase-polymerase chain reaction assay. None of the samples was positive for SLEV, thus failing to support the hypothesis.

Biological Collections and Systematics

The biological collections of the Illinois Natural History Survey (INHS) are an invaluable and irreplaceable resource. First established in the mid-19th century for the purpose of documenting the flora and fauna of Illinois, the collections preserve some of the earliest natural history specimens collected in the Midwest. From their humble beginnings, the INHS collections have grown into important, internationally known repositories of specimens and information. Although the collections currently function primarily as tools for basic research in biological systematics, evolution, and ecology, they are also of crucial importance for education, applied biology, and conservation of natural resources. Through the ongoing efforts of INHS staff and improvements in information retrieval technology, the collections continue to become more accessible to researchers, conservationists, educators, policymakers, and the general public. For a breakdown of the size of our various collections and other information, see the table under the Biological Collections heading in the Public Services section of this report.
Natural history collections make up the primary source of information on the earth's biodiversity and, thus, are indispensable for systematics, the science of classifying and naming organisms. Systematists rely on preserved museum specimens for describing species, creating keys for their identification, and documenting their geographic and seasonal distributions. Properly preserved specimens may also serve as sources for the biochemicals (e.g., DNA, proteins) used in molecular genetic analyses. Such analyses have become increasingly important in attempts to create natural classifications of species based on their hypothesized phylogenetic relationships.
INHS systematists are engaged in a wide variety of research projects aimed at facilitating a greater understanding of the biota of Illinois and the earth in general. These studies range in scope from species lists of particular Illinois habitats to comprehensive revisionary studies that seek to reclassify all known species of a selected group of organisms. From the collections, systematists glean information ranging in detail from the geographical data printed on specimen labels to the fine details of morphology and DNA sequences, which provide clues to the evolutionary origins and relationships of species. Through basic research, INHS systematists attempt not only to fully document the biotic diversity of Illinois but also to place the Illinois biota within a global biogeographical and historical context. In addition to their own research contributions, INHS curators and collection managers annually make numerous specimen loans to other qualified researchers worldwide who rely on these loans for their research. Thus, each year, use of the collections by INHS staff and scientists at other institutions yields numerous scientific publications, each of which represents a fundamental contribution to knowledge of the earth's biota.
Systematists are not the only group making use of the INHS collections. The collections and databases are used frequently by conservation biologists interested in tracking the distributions of threatened and endangered species and monitoring changes in their distributions over time. Also, because certain species are considered to be indicators of high-quality habitats, data from specimens of these species may also be used to determine where such habitats occur. Several studies based on the historically important specimens in INHS collections have demonstrated losses of native species in Illinois, as well as introductions of many non-native species, in recent years. Without the collections there would be little baseline information on the original Illinois biota for comparison with the present flora and fauna of the state. Ongoing sampling projects will continue to document changes in the biota over time and will facilitate long-term monitoring and conservation of the biotic resources of Illinois and other regions.
Accurate identification of species is crucial not only for biological research but also for economic reasons. Incorrect identification can lead to costly errors, such as application of a pesticide when the species present is a nonpest species. Because species identifications, particularly in poorly studied groups like invertebrates, are often imprecise, voucher specimens are needed to document that the species subjected to a particular study or experiment have been identified correctly and to avoid the propagation of identification errors in the scientific literature. Biologists who work with organisms that are difficult to identify should always deposit specimens of the species under study in a permanent collection so that the identifications can be verified by future researchers. The INHS collections serve as important repositories for such voucher specimens from applied biological studies, such as those focusing on the biological or chemical control of agricultural pests or invasive species.
Members of the general public frequently make indirect use of the collections by bringing specimens of plants and animals in for identification by INHS staff. Because adequate identification keys are simply not available for many groups of organisms, INHS staff members often must identify unknown specimens by comparing them to the authoritatively identified reference specimens in the INHS collections.
In addition to their value for research and identification, the collections serve important educational functions. Each year, tours of the collections are offered to groups of elementary school students to help educate them about the earth's biotic diversity. Many undergraduate and graduate students from the University of Illinois are also gaining invaluable research experience by working in the collections.
To increase their usefulness, collections must not only be maintained but also must continue to grow through the acquisition of new specimens, and efforts must be made to facilitate the efficient retrieval of information on the specimens and their associated ecological and distributional data. Many of the INHS collections experienced significant growth during fiscal 1998, both through collecting by INHS staff and by donations and exchanges of specimens. Most of the new specimens acquired represent new geographic records and some represent species new to science.
Not only are the INHS collections growing in size but information on the collections is becoming more readily accessible. The INHS continues to be a leader in efforts to make natural history collection data available on-line via the Internet and World Wide Web. Data from nearly all of the collections have been entered into computerized databases and many of these databases are currently available for searching or downloading via the Internet. Perhaps the year's most notable achievement was the completion of the vascular plant database, which contains information on nearly 200,000 specimens. Thus, collection data for plants, vertebrates (fishes, amphibians and reptiles, and mammals), and several of the invertebrate collections (annelids, crustaceans, mollusks), together comprising over 1 million specimen records, are all currently available on-line. Presently, databasing efforts are focused on the insect collection which, at over 6 million specimens, is by far the largest of the INHS collections and one of the ten largest insect collections in the U.S.
Efforts are under way to provide fully searchable specimen databases of all of the collections and to integrate these databases with Geographic Information Systems (GIS). This will provide the tools necessary for researchers and educators worldwide to conduct a wide variety of analyses of species distributions in space and time.

DATABASES AND ON-LINE INFORMATION

Prairie remnant database
W. Handel
The Illinois Department of Transportation has requested the creation of a database for roadside prairies. The prairie ecosystem is one of the rarest habitat types in Illinois, and a large percentage occurs along roadside and railway right-of-ways. Their position in the landscape makes prairie ecosystems vulnerable to human disturbance, such as pesticide spraying, mowing, and cultivation. It is hoped that the database can be used by state agencies to locate prairie remnants and minimize impact by human activity.

Soybean Insect Research Information Center (SIRIC)
M. Irwin, E. Armbrust, L. Hanson, E. Brewer
SIRIC is a reference center for the study of arthropods associated with soybeans and is intended to serve as a first line of defense against outbreaks of new soybean pests. The center produces an electronic database that represents the world's scientific and research literature on soybean-related arthropods, and collects and stores printed copies of 99% of the papers found in the database. First established in 1969, SIRIC was closed in 1990 and re-opened with a new librarian in January 1997. The database is now available on the Web, and is being updated with information from 1990 to 1998--http://insectweb.inhs.uiuc.edu/Soy/SIRIC/index.html

MANDALA: a database for systematics research
G. Kampmeier, M. Irwin, F. Thompson (USDA-ARS Systematic Entomology Laboratory, Smithsonian Institution)
MANDALA is an interwoven suite of databases developed for our National Science Foundation's Partnerships for Enhancing Expertise in Taxonomy project on the Diptera family, Therevidae. Specimens receive unique numbers and are identified by taxon, with history of the name, including use in the literature, misuse or changes, hierarchical classification, holotype location, valid name, and synonomies. Collecting locality including latitude and longitude for biogeographic studies, conditions surrounding the collecting event, floral and faunal associations, collectors, determinations, illustrations, and where the specimen is and has been housed are also recorded.

Therevids on the WWW
G. Kampmeier, M. Irwin
A critical part of our National Science Foundation's Partnerships for Enhancing Expertise in Taxonomy project on the fly family Therevidae involves electronic dissemination of information. Our web site http://www.inhs.uiuc.edu/cee/therevid/ shares information with the world on this fascinating family of flies. These predaceous flies, whose larvae live in friable soils on nearly every continent in the world, are critical to the sound functioning of arid and semiarid environments, including agroecosystems and forests in those zones. Reports of ongoing research and expeditions, a chance to meet the participants in therevid research, news, even therevid diversions are all featured at our web site.

Bibliography of aquatic worms of North America
M. Wetzel
A bibliography of aquatic Annelida of North America, including the groups Acanthobdellae, Aphanoneura, Branchiobdellae, Hirudinea, Oligochaeta, and selected Polychaeta is being compiled. This annotated bibliography includes journal articles, books, scientific reports, meeting and symposium proceedings, and government documents that address the systematics, ecology, taxonomy, distribution, and physiology of aquatic worms. To date, over 4,000 citations have been entered into a computer database; those published during the years 1993 through 1997 are accessible via the INHS World Wide Web server at:
http://www.inhs.uiuc.edu:80/~mjwetzel/mjw.inhsCAR.html#BIBannel

Nomenclature of aquatic worms of North America
M. Wetzel
The American Fisheries Society Committee on Names of Aquatic Invertebrates (CNAI) prepares checklists of names to achieve uniformity in vernacular and scientific nomenclature. Committee member M. Wetzel, who co-chairs the CNAI subcommittee on aphanoneuran and clitellate Annelida, is helping compile the list of scientific and common names of North American nonpolychaete annelids. Over 830 species among 27 families and 195 genera are included. A working draft of this list, available via the INHS World Wide Web server at http://www.inhs.uiuc.edu:80/~mjwetzel/WONA2feb98.html has been posted to solicit comments and published distribution records of annelids for inclusion in a volume to be published in 1999.

Directory of annelid systematists, ecologists, and field zoologists
M. Wetzel
A directory of systematists, ecologists, and field zoologists who study annelid worms is being prepared. Searchable fields in the database include institutional affiliation, postal and electronic mail addresses, web sites, telephone numbers, and a summary of each researcher's areas of interests and expertise. To date, the database includes over 275 scientists from 38 countries. Information provided by respondents at the International Symposia on Aquatic Oligochaete Biology has been included in this database, which will soon be available via the World Wide Web. Contact information for over 100 active researchers is available via the INHS World Wide Web server at
http://www.inhs.uiuc.edu:80/~mjwetzel/ISAOBdir.html

An Ephemeroptera, Plecoptera, and Trichoptera (EPT) database: Internet access and geographic information system linking of collections at the INHS
R. DeWalt, C. Dietrich, K. Zeiders, D. Webb, T. Kompare
The INHS maintains large collections of environmentally sensitive Ephemeroptera, Plecoptera, and Trichoptera (EPT) from Illinois and North America. Much of this material was amassed during 1910-1950 before the worst environmental degradation took place and represents irrefutable and irreplaceable evidence of the existence of a widespread, sensitive fauna. The INHS is computerizing its specimen-level data. All records are being given map references, allowing easy mapping of distributions of each species. Compiling EPT specimen records into a single Internet-accessible database will provide an invaluable tool for systematists, ecologists, pollution biologists, and natural heritage organizations.

Directory of mollusk collections of the world
K. Cummings, A. Oleinik (Purdue University), J. Slapcinsky (Field Museum), T. Kompare
A searchable directory of museums with collections of recent and fossil mollusks has been compiled. The list includes over 50 museums in 30 states or provinces of the U.S. and Canada and 35 others from 25 countries in South America, Europe, Asia, and Australia. The list includes the name, address, phone, fax, and e-mail address of the curator and institutional acronym. Information is being added on the number of specimens and the geographic scope of each collection. The collections list is accessible on the INHS World Wide Web server at: http://www.inhs.uiuc.edu/cbd/collections/mollusk_links/museumlist.html

Type catalog of freshwater mussels (Unionoida) of the worldM
K. Cummings
A type catalog of freshwater mussels (Unionoida) of the world is in preparation. To date, over 3,000 nominal taxa have been entered into a computerized database. The database contains information on the original name, author, date, citation, page number, reference to figured specimens, type locality, deposition of type material, and names used in earlier monographs. Photographs of some of the types have been scanned and added to the database. The literature citations are linked to a computerized bibliography containing over 7,000 references on freshwater mussels. The database eventually will be placed on the INHS World Wide Web server.

Freshwater mussels of Illinois
K. Cummings
A new Freshwater Mussels of Illinois (Mollusca: Unionacea) is being prepared. This monograph will reflect changes in nomenclature, provide keys for identification, include distribution maps, and update the biological literature since the 1967 publication of P.W. Parmalee's Fresh-water Mussels of Illinois. A computer database containing verifiable collections-based information on the distribution of Illinois mussels has been completed and includes data from the Survey, the University of Illinois Museum of Natural History, the Illinois State Museum, the Field Museum of Natural History, the Chicago Academy of Sciences, and eight out-of-state museums.

Freshwater mussel bibliography
K. Cummings, A. Bogan (North Carolina State Museum of Natural Sciences), G. Watters (Ohio Biological Survey), C. Mayer
A bibliography of the Naiades or freshwater mussels (Mollusca: Bivalvia: Unionoida) is being prepared. The goal is to provide a comprehensive list of references to freshwater mussels with an emphasis on North America. The bibliography will contain references to books, chapters, journal articles, government documents, popular articles, theses, and dissertations. In addition to title, the bibliography can be searched by numerous topic areas or geographic regions. Over 7,000 references have been entered into a database. If funding becomes available the database will be accessible over the World Wide Web to make the information readily available to most researchers.

Freshwater mussel / host database
K. Cummings, G. Watters (Ohio Biological Survey), C. Mayer
A database of freshwater mussels (Unionoida) and their hosts has been compiled and is expected be placed on the INHS World Wide Web server in 1998. To date, over 1,000 mussel/host relationships have been entered. Information with each record includes the species and family of both mussel and host, evidence for the host relationship (field identification, lab transformation, etc.), and the literature citation and page number for the original work.

Directory of freshwater mussel researchers
K. Cummings
A searchable directory of freshwater mussel researchers has been compiled. The list includes over 400 individuals from throughout the U.S. and Canada and from various countries in South America, Europe, Asia, and Australia. The list includes each researcher's name, institution, address, phone, and e-mail address. Plans for the coming year include adding information on specific research interests of each researcher. The list is accessible on the INHS World Wide Web server at http://www.inhs.uiuc.edu/cbd/collections/mollusk_links/uniopeoplelist.html

SYSTEMATIC STUDIES

Systematic studies of Rosaceae
K. Robertson
Work continued on long-term systematic studies of the Rose family (Rosaceae), especially the apple subfamily (Maloideae). In October 1997, Dr. Robertson presented a paper at a symposium on Rosaceae at Royal Botanic Garden, Edinburgh, Scotland. He is co-organizer of another symposium on Rosaceae to be held at the 1999 International Botanical Congress. With D.R. Morgan (Western Washington University) and C.S. Campbell (University of Maine), Robertson is investigating the evolutionary origin of the pome fruit using morphological and molecular techniques. Robertson is also collaborating with Chinese botanists on the forthcoming English translation of the updated Flora of China.

Contributions to The Flora of North America
G.A. Levin, K. Robertson
Botanists from throughout North America are preparing manuscripts on their taxonomic specialties for a major new project that will cover all the flowering plants, conifers, and ferns for the North American continent (excluding Mexico). Survey staff members are contributing treatments of the Haemodoraceae (bloodwort family), Erythronium (trout lily, dog-tooth violet) of the Liliaceae (lily family), Acalypha (mercury) and Drypetes(Guiana plum) of the Euphorbiaceae (spurge family), Amaranthus (pigweed) of the Amaranthaceae (pigweed family), and numerous genera of the Rosaceae (rose family). The multi-volume publication will be titled The Flora of North America.

Systematics of three-seeded mercuries
G. Levin
Sixteen species in the plant genus Acalypha are found in the United States, including six in Illinois. Taxonomic distinctions within several species groups have been perplexing. Research including extensive field studies have shown that in some groups this is because supposedly different species are actually indistinguishable. In other groups, however, the species are clearly distinct but some of the characteristics that have been used historically to separate them are unreliable. Because this genus includes both widespread common species and rare species, understanding the taxonomy is vital for conservation and policy-making.

Systematics of Leuctra ferruginea, a stonefly
R. DeWalt
Stoneflies live in streams, and the presence of several species usually indicates good water quality. The Leuctra ferruginea species group contains several small species in eastern North America. New species may await discovery in the Gulf South region. Study of museum and newly collected specimens will result in a key to all known members, a summary of their distributions, and an analysis of the members' relationships, including that for our own member of the group, L. rickeri, found in the Shawnee Hills region in southern Illinois.

Systematics of New World stiletto flies
D. Webb, M. Irwin
Revisions of the genera Tabuda, Tabudamima, and a closely related new genus were completed as part of an ongoing study of the systematics, phylogeny, and zoogeography of the fly family Therevidae (Diptera), which has ecological and potential economic importance. These revisions involve the description of numerous new species in addition to clarifying the descriptions and names of known species. Keys that allow other scientists to identify the stiletto flies are also included. The ultimate objective is to revise all of the New World genera and to determine their relationships with Old World and Australasian relatives.

Systematics of the Chamaemyiidae
S. Gaimari, M. Irwin
Chamaemyiid larvae (Diptera: Chamaemyiidae) are important predators of soft-bodied homopterans such as aphids, scales, and mealybugs, many of which are pests. Despite their potential importance as predators of these insects, Chamaemyiidae are poorly known taxonomically. Survey researchers are studying several aspects of this predaceous family, including biological studies, revisions of several poorly understood and understudied genera, and descriptions of several new genera and species. Survey researchers are also considering the systematic relationships within the family, using adult and immature morphological characters, life history information, and molecular techniques.

Studies of a new tribe of Therevidae
S. Gaimari, M. Irwin
As larvae, therevid flies are subterranean predators of larval insects in loose, friable soils. A group of 10 genera surrounding Ozodiceromyia and Cyclotelus has been assigned tribal status in a phylogenetic and biogeographical study, with 5 new genera proposed. Their phylogenetic relationships have been analyzed using cladistic methodology, and the tribe is supported as monophyletic by several convincing synapomorphies. This tribe is mostly New World, including the Greater Antilles, but three small genera are Asian. Cladistic biogeographical analyses suggest that their current distribution was influenced by the Beringian land bridge between Asia and the New World.

Revision of the genus Ozodiceromyia
S. Gaimari, M. Irwin
As larvae, therevid flies are subterranean predators of larval insects, such as beetle grubs. The genus Ozodiceromyia (Diptera: Therevidae) contains 115 Nearctic and northern Neotropical species, of which 80 are new to science. These important predators may be useful in assessing health of dry, friable soil habitats. Despite its abundance in agricultural habitats, Ozodiceromyia is poorly understood taxonomically. Survey researchers are seeking to better understand the genus and relationships with other therevid genera, as well as relationships within the genus. A full phylogenetic and biogeographic revision is near completion, using traditional adult taxonomy and molecular systematic studies.

Revision of the genus Lindneria and a new therevid species from Dominican amber
M. Metz, M. Irwin
The Neotropical genus Lindneria (Diptera: Therevidae) is known from few specimens and is rarely collected. The holotype of the type species of Lindneria (previously thought destroyed during WWII) has been rediscovered, removing the nomenclatural status of the type species from ambiguity. A second species (in the genus Psilocephala) will be moved into Lindneria. Currently, one putative synapomorphy supports the monophyly of these two species. Phylogenetic relationships among the remaining specimens near Lindneria, including one from Dominican amber, will be estimated using parsimony analysis. The amber specimen will likely be described as the type species for a new genus.

The diversity of dipteran families and their parasitization by trombidioid mites in a xeric woodland habitat
M. Metz, M. Irwin
Thirty-eight families of brachyceran Diptera were collected using malaise traps in dry forest habitats in New Mexico. Parasitism by trombidioid mites was high (24%) on Therevidae with up to 22 mites per individual. Tachinidae were also parasitized at a relatively high rate (16%). Eleven other dipteran families were parasitized at lower rates. Little is known about therevid biology, so ecological associations may provide much needed biological information. Alternatively, Tachinidae have been used as biocontrol agents and their biology has been studied extensively. Information about behavior, ecology, and life history of Tachinidae might provide insight into the lesser-known Therevidae.

Differential variation of body and genitalia size using Ozodiceromyia nanella (Diptera: Therevidae) as a model
M. Metz, M. Irwin
Work continues on the investigation of the morphological variation of genitalic characters in relation to body size using morphometric analysis. Measures on specimens collected in 1997 from the same population suggest that the relationships between genitalic and body size characters is not constant through time and may be a focus of evolutionary processes. Specimens will be collected in 1998 to complete the study.

Systematics of the Phylum Microsporidia
J. Maddox, L. Solter
The Phylum Microsporidia is a group of eukaryotic unicellular pathogens. Although different species are found infecting many animal host species, often as opportunistic pathogens, microsporidia are primarily pathogens of arthropods. Many species are important natural control agents of their hosts. Approximately 1,000 species have been described, most from insects, but the phylogenetic relationships between genera are poorly known and the significance of the relationship between molecular and morphological characters is undetermined. New species are being described and the importance of morphological characters in relation to molecular characters is being studied.

Systematics of aquatic worms in Illinois
M. Wetzel
The INHS Annelid Collection, consisting of approximately 295,000 specimens, includes members of the Aphanoneura, Branchiobdellida, Hirudinea, Oligochaeta, and Polychaeta. Although 74% of the material has been collected from Illinois, specimens from 45 other states, four Canadian provinces, and six countries also are included. A computerized database is being compiled. During FY98, over 3,000 specimens from Illinois, four other states, and Ontario, Canada, were added to the collection. Illinois is known to have 131 species of aquatic worms representing 71 genera and 15 families. A summary of the INHS Annelida Collection is available via the INHS World Wide Web server at http://www.inhs.uiuc.edu:80/~mjwetzel/INHS.AnnelColl.html

Cryptic natural resources: soybean endophytes
W. Chen, J. Crane
Fungal endophytes are fungi established inside healthy aerial plant tissue without causing apparent injury to the host. The close ecological association between plants and endophytes is mostly mutualistic and confers many beneficial effects to the host plants, including increased disease resistance. Fungal endophytes are abundant in soybean plants, but their role on soybean health is not known. Scientists at the Survey are studying the taxonomy of soybean fungal endophytes and exploring the possibility of using the endophytes to improve soybean health, such as resistance to diseases. Fungal endophytes of soybean are our cryptic natural resources and remain to be exploited.

Phylogeny of freshwater ascomycetes
W. Chen, J. Crane
Illinois streams and rivers provide unique habitat for a group of ascomycetes. This group of ascomycetes has developed scolecosporous ascospores, an adaptation to the aquatic environment. Mycologists at the Survey in cooperation with mycologists at the University of Illinois have been studying the phylogeny of the freshwater ascomycetes with fungi from other habitats using rDNA sequences. Scolecosporous ascomycetes from freshwater habitat formed a monophyletic clade, whereas scolecosporous ascomycetes from the marine environment formed another clade distantly related to freshwater ascomycetes. However, the marine ascomycetes are not monophyletic, providing new insights about evolution of freshwater and marine ascomycetes.

Isthmosporella pulcra, a new genus and species of freshwater fungus
L. Crane, C. Shearer
During a latitudinal survey of the freshwater ascomycetes of North America, a fungus with unusual ascospores was found on submerged wood collected from a lake. Its features indicate that this taxon belongs in the family Phaeosphaeriaceae. None of the genera now included in this family has isthmoid ascospores and the fungus is therefore described as a new genus and species. Indeed this spore type is rare in ascomycetes in general. One of the few genera with isthmoid ascospores is Vialaea. Fungi in this genus, however, have unitunicate asci, whereas Isthmosporella has bitunicate asci.

Phylogeny and classification of world leafhoppers and treehoppers
C. Dietrich
Comprising over 25,000 described species, leafhoppers and treehoppers (Membracoidea) are among the dominant herbivorous insects in grassland and forest habitats throughout the world. Lack of a sound phylogenetic classification of this group has hindered attempts to understand the evolutionary factors that enabled these insects to diversify in a wide variety of habitats, including agroecosystems. Work is under way on a phylogenetic analysis of the major lineages of Membracoidea that will lead to an improved classification and identification aids for the group. The analysis combines morphological and molecular data in an attempt to arrive at the best possible estimate of phylogeny.

Evolutionary history of the fish subgenus Catonotus
J. Porterfield, L. Page, T. Near
Unique nesting sites, breeding behaviors, and morphologies make the darters in the subgenus Catonotus (genus Etheostoma) particularly fascinating. Four species in this group are found in Illinois. One species, the fantail darter, is widespread; the other three are restricted to the Shawnee Hills and contribute to the unique fauna of southern Illinois. Complete mitochondrial cytochrome bDNA sequences and a morphological data set are being used to estimate phylogenetic relationships among the 18 species in the subgenus. From this phylogeny, the behavior and morphology, as well as the ecological requirements, of species of Catonotus can be better understood.

Evolution of size in North American freshwater fishes
J. Knouft, L. Page
Body size is one of the most important traits of a species. The relation-
ship between body size and ecological characteristics has the potential to explain many patterns seen in nature. Cope's Rule, recognized since 1887, states that groups of organisms tend to get larger over time. However, the rule has been tested only with fossil organisms. The evolution of body size in living groups of North American fishes is being examined using published phylogenies. Results indicate that most groups of fishes, in contrast to Cope's Rule, evolve toward a smaller body size. The pattern described is extremely important in understanding community structure and species distributions.

Variation in the blackside darter
R. Steinberg, L. Page
The blackside darter, Percina maculata, is a widely distributed pool-inhabiting darter that is one of the most common darters in Illinois. The species has been described as "probably a complex of subspecies" although how the Illinois populations vary in relation to other populations is unknown. The most recent large-scale study on the blackside darter revealed morphological variation to be especially high among populations inhabiting tributaries of the Ohio River. Research is currently being conducted in order to describe this variation and investigate the possibility of populations being taxonomically distinct.

Evolutionary relationships of snubnose darters
J. Porterfield, L. Page
Snubnose darters form a large group within the genus Etheostoma, the most diverse genus of North American freshwater fishes. Snubnose darter taxonomy has been very controversial. The ongoing debate concerns whether the banded darter, Etheostoma zonale, an Illinois species, is closely related to the snubnose darters which, except for the banded darter, are confined to the southeastern U.S. Phylogenetic analysis of cytochrome bDNA sequences for 32 species suggests that the banded darter is closely related to four snubnose darters. This and other relationships found in the study are generally congruent with morphological data.

COLLECTIONS

Dipterists sort INHS museum collections
M. Irwin, D. Webb
One aspect of informal training of our therevid systematics group comes in the form of a weekly "sort night." After a quick dinner together they hit the INHS insect collection, picking through the unsorted Diptera or working on critical Diptera-related projects: Mark Metz is curating the Syrphidae; Kevin Holston the Asilidae; and Steve Gaimari the unsorted Acalyptrates. It is an evening to learn from one another and help the museum label and classify specimens so that they can be sent to other specialists for determination. Visiting dipterists also lend their expertise when present on Tuesday nights.

New nematode parasite of earthworms
E. Zaborski, S. Roberts
Earthworms are thought to be free of important nematode parasites. During the winters of both 1996-1997 and 1997-1998, Survey researchers collected nightcrawlers, Lumbricus terrestris, that were parasitized by a nematode. Within days, infected earthworms died and released tens of thousands of nematodes. Researchers have been able to keep this rhabditid nematode in culture in the laboratory for over a year, both by infection of healthy nightcrawlers and by culture on artificial media. Further studies are being conducted in the laboratory to identify this nematode, describe its biology, and understand its importance as a mortality factor for earthworms.

Collection of viable microsporidian spores
L. Solter, J. Maddox
Scientists at the Illinois Natural History Survey curate a large collection of viable microsporidian species, both described and undescribed. More than 1,000 samples of microsporidia isolated from hosts in the Orders Lepidoptera, Heteroptera, Coleoptera, and Diptera are stored in liquid nitrogen and have been shown to be infectious to natural hosts after more than 25 years of storage in 1:1 sterile water: glycerol. The collection is a source of many potential biological control agents and is important for future studies of previously described pathogens.

Distribution of Illinois semiaquatic bugs
S. Taylor, J. McPherson (Southern Illinois University)
The distribution of semiaquatic bugs (water striders and related families) in Illinois is being documented through field collections and examination of museum material, and keys to more than forty-five species are being developed. Current efforts focus on filling gaps in the known distributions of species and collecting data on microhabitat use and species associations. Several species not previously reported from Illinois have been collected during the present study. A computer database of Illinois semiaquatic bugs and distributional maps for the species are also being developed. This study will provide a useful tool for the identification and conservation of these insects.

FLORAL AND FAUNAL SURVEYS

Leafhoppers and treehoppers of Illinois
C. Dietrich
More than 800 species of leafhoppers and treehoppers have been collected in Illinois and over 50 of these are known only from this state. Field surveys are under way to clarify the distributions, hosts, and conservation status of these plant-feeding insects, many of which are restricted to relatively undisturbed habitats and may be good indicators of habitat quality. Surveys in Illinois this year, some carried out as part of the Critical Trends Assessment Project, yielded a new state record and numerous new county records.

Prairie insect inventory
D. Voegtlin, C. Dietrich, K. Zeiders, J. Bouseman
In the third year of this study the focus was on four sand prairies in Mason County. The insect and spider fauna in these prairies is quite different from that in the prairies sampled in the previous two seasons. Some rare insects were found as well as some new records for Illinois. At two sites where management has included fire, burned areas seem to be lacking in insects that survive the winter as eggs on the above-ground stems of their host. Data collected in this study are being compiled by the U.S. Fish and Wildlife Service and will be examined in relation to fire history.

Reevaluation of the spring and summer stonefly fauna of Illinois
R. DeWalt
Stoneflies are the most pollution-sensitive aquatic insect group. Theodore Frison and Herbert Ross, former employees of the Survey, amassed data on the distribution of Illinois stoneflies during 1930-1950, before major changes in stream quality took place. A new survey of stonefly distributions is now being undertaken, beginning with sampling in the bluffs above the Rock and Mississippi rivers in northwest Illinois. Already, vast differences between the stoneflies found during 1930-1950 and the present are evident. This study will quite possibly demonstrate that stonefly populations have been dealt a severe blow in Illinois streams and rivers since early 1900.

Summer mayfly, stonefly, and caddisfly species richness and biotic index values at eight lower Illinois River basin sites
R. DeWalt, D. Webb
Mayflies, stoneflies, and caddisflies include some of the most sensitive aquatic insect species. Recent efforts by the U.S. Geological Survey-National Water Quality Program to assess the health of the lower Illinois River basin presented an opportunity for collaboration with INHS aquatic entomologists. Collections of adults during summer 1997 found several sites with high species richness. These were most often small- to medium-sized streams. Low richness values were found for several of the largest river sites, especially sites that carried a heavy suspended sediment load and had shifting sand bottoms.

Winter stoneflies of Illinois
D. Webb
A 10-year survey of the winter stoneflies (Plecoptera) of Illinois was completed to determine their current spatial and temporal distribution relative to collections made by INHS researcher Frison during the 1920s and 1930s and Ross and Ricker in the 1960s. The two earlier studies of the winter stoneflies of Illinois provide historical records of their distribution prior to much of the environmental and agricultural changes in Illinois. The results reveal that certain species have experienced reduction in distribution or have even disappeared from Illinois.

Fishes of Illinois: 100 years of change
L. Page, M. Retzer, M. Sabaj
The third survey of Illinois fishes is being conducted with assistance from the Illinois Department of Natural Resources Division of Fisheries. The first survey (published in 1908) documented 187 native and 1 non-native species. By the second survey (1979) the number of natives had dropped to 179 and non-natives had risen to 6. Recent data suggest that only 176 native fishes remain, and non-native species have increased to 12. Although some native species are increasing in abundance, many survive only as small populations in highly fragmented habitats. Most changes have resulted from human effects such as increased sedimentation. This study will enhance our ability to protect and restore aquatic communities.

Botanical survey of the Richardson Wildlife Foundation
W. Handel, L. Phillippe
Richardson Wildlife Foundation is a large tract of native and reconstructed sand pond, sand prairie, and sand dune habitat in Lee County. A floristic survey and vegetation analysis is being conducted on the native habitats to determine species composition and distribution. The floristic survey and vegetation analysis has been expanded from the previous year to include other native plant communities besides mesic sand prairies, including wet- mesic to wet sand prairies and sedge meadows.

Plant collections
W. Handel, S. Hill, G. Levin, L. Phillippe, K. Robertson, J. Taft
The INHS plant collections have exceptional historical and scientific value to the people of Illinois. The collections are regularly used to map plant distributions, identify unknown samples, and support other types of agricultural and botanical research. Trips throughout Illinois and surrounding regions continue to be made to increase our knowledge of the state's flora. Special efforts are made to collect in poorly known regions of the state, to document species not previously seen in the state, and to document climatic changes. Collections in nearby states allow better understanding of our flora and facilitate identification of plants, including agricultural weeds, that may yet be found in Illinois.

Distribution of burrowing crayfishes in northeastern Illinois
C. Taylor
Recent sampling in northeastern Illinois has provided new distribution records for the digger crayfish, Fallicambarus fodiens, a species previously thought to be experiencing a range reduction in Illinois. This work has documented several large populations of F. fodiens in the Chicago metropolitan area and is also providing new data on the habitat tolerance of another burrowing species, the prairie crayfish, Procambarus gracilis.

A latitudinal survey of freshwater ascomycetes
L. Crane, C. Shearer
Submerged plant debris were collected along two N-S gradients in North America for three years. The ascomycete fungi growing on the debris were isolated. Thus far, 450 different taxa spanning a broad taxonomic range have been found. A variety of spore adaptations to the aquatic habitat were encountered, including long filiform spores and spores with large, sticky gelatinous sheaths that may allow the spores to attach to substrates in moving water. Species richness varied with latitude, with the greatest diversity found at latitude 40[[ring]]-44[[ring]]N. Support for this project came from the National Science Foundation.

Statewide biological survey and assessment program
L. Page, C. Phillips, et al.
Under contract with the Illinois Department of Transportation, INHS researchers conduct surveys for plants and animals in habitats associated with highway and bridge construction projects and wetland mitigation sites. In particular, these surveys are designed to detect habitat for endangered and threatened species listed by the U.S. Fish and Wildlife Service or the Illinois Endangered Species Protection Board; habitat for species with unique, restricted, or declining ranges in Illinois; and high-quality natural communities. During 1997, surveys were conducted in 60 Illinois counties.

Chicago Wilderness

"Chicago Wilderness" refers to both a place and a partnership of organizations. The place is a regional nature reserve that currently comprises over 200,000 acres of protected habitat. The reserve is located in northeast Illinois and includes the six- county Chicago region. Major habitats in the region include forests, oak savannas and woodlands, grasslands, streams, and wetlands. Biologically interesting and important habitats within each of these categories can be found within the reserve. For example, marshes and shrub swamps, sedge meadows, fens, and bogs make up the complex of wetlands in the region. The habitats and associated biodiversity in the Chicago Wilderness are significant at the state, national, and global scale. The known plants and animals in the region include 181 species that are on the threatened and endangered list of the State of Illinois. The native grassland and oak savannas in the Chicago Wilderness are some of the most important examples of these habitats in the state and the region. This level of biodiversity is remarkable given the metropolitan nature of the region.
The Chicago Wilderness partnership is made up of over 60 public and private organizations; the Illinois Natural History Survey is an active member of the Chicago Wilderness. These organizations have joined in a common effort to protect, manage, and restore the ecosystems and biological communities of the region. Specific activities include ecological inventory, the creation of recovery plans for various types of biologically significant habitats, restoration research, education and outreach, and the identification of regionwide conservation priorities. Scientists from the Illinois Natural History Survey have participated in many of these activities as principle investigators, participants in workshops, or as members of various teams that have been formed within the Chicago Wilderness, such as "Science and Land Management."

Bluegill and largemouth bass populations in the Chicago area forest preserves
J. Hoxmeier, D. Wahl
Chicago area forest preserve lakes provide many angling opportunities for local residents; however, factors affecting growth and survival of fish in urban settings have received little attention. The effects of angling can be dramatic in this area given the unusually high fishing pressure. Researchers are currently studying bluegill size structure along with largemouth bass recruitment and stocking strategies in several Chicago area forest preserve lakes. Survey researchers will eventually develop and test several management strategies to improve bluegill size structure. The results from this study should give scientists a better understanding of factors affecting growth and survival of largemouth bass and bluegill, and how to manage for quality fisheries in metro areas.

Purple loosestrife biological control education program
D. Voegtlin, M. Jeffords, R. Wiedenmann, S. Post
Twenty five Chicago-area middle and high schools participated in an educational program covering biodiversity, wetlands, and biological control. The theme that tied these topics together was the ongoing biological control program for purple loosestrife, in which leaf-feeding beetles specific to purple loosestrife are being mass reared and released. Educators attended an all-day workshop presented by INHS scientists at which written materials and exercises were explained. Each educator received a complete kit containing all the materials necessary for classroom exercises and experiments and for rearing the beetles. The materials were developed by INHS scientists with funding from Chicago Wilderness.

Distribution and abundance of the Asian tiger mosquito and other mosquito vectors inhabiting waste tires in the Chicago metropolitan area
R. Novak, R. Cieslik (Chicago Department of Health)
This is a continuing investigation on the distribution and expansion of the Asian tiger mosquito, Aedes albopictus, in the Greater Chicago metropolitan area. Various sampling methods are used to monitor the density of mosquitoes and as a tool to determine the spread of Ae. albopictus. This species and other vector mosquitoes, that is, Culex pipiens and Ae. triseriatus, collected by public health, mosquito control districts, and medical entomology personnel within this area, are also being examined for the presence of St. Louis encephalitis and La Cross encephalitis viruses.

Endangered, Threatened, and Rare Species

The first European settlers to arrive in Illinois encountered a fabulous natural landscape. The northern part of the state was a mosaic of many prairies types, wetlands, forests, savannas, and rocky streams. Along the magnificent natural shoreline of Lake Michigan were beaches, sand dunes, swales, and cliffs dissected by wooded ravines. Central Illinois was primarily tallgrass prairie, spectacular at all seasons, and dotted with isolated woods known as prairie groves. Towards the west and south the prairies gave way to mature forests and tall cliffs of sandstone and limestone. Occurring at the extreme southern part of the state were swamps filled with giant bald cypress and tupelo trees, reminiscent of areas much farther south. The ecological diversity of Illinois is reflected in the large number of native species of plants and animals. A compilation by Survey staff estimates that there are over 54,000 species of organisms native to Illinois, including 2,574 plants, 20,000 fungi, 28,000 insects and relatives, 374 molluscs, 187 fishes, 39 amphibians, 59 reptiles, 297 birds, and 67 mammals.

The rapid settlement and development of Illinois dramatically affected its biology. Most of this development has been based on the conversion of original native habitat to agricultural fields and areas for industry and urban development. Logging, mining, and pollution have degraded the remaining natural habitats. Regrettably, only a tiny fraction of our original ecosystems has survived. In this regard we rank 49th among states (Iowa is 50th).

The loss of habitats has been responsible not only for the extinction of some species but also for a drastic reduction in the abundance of many native species. Currently, there are 511 species listed as threatened or endangered, mostly plants and conspicuous animals, and it is estimated that at least 115 species have been lost from the state. These losses include large obvious species like bison and whooping cranes, and diminutive species like the bog clubmoss and the rosefin shiner. The vast majority of endangered and threatened species of Illinois are restricted to remnants of high-quality natural communities, such as are found in Illinois Nature Preserves and other natural areas.

There are several reasons for species being rare and consequently listed as endangered or threatened in Illinois: (1) The species are naturally sparse or infrequently occurring, probably even prior to European settlement. Queen-of-the-prairie and four-toed salamander are examples. (2) The species occur in Illinois at the edge of their natural range. These species are common, often abundant, outside Illinois. Examples are prairie dandelion and the bigeye chub. (3) The populations that occur in Illinois are geographically separated, or disjunct, from the principal range of the species. Some examples for Illinois include leafy prairie clover, yellow mud turtle, and harlequin darter. (4) Species are restricted or endemic to Illinois and do not occur elsewhere. Only two plant species are considered endemic to Illinois--Kankakee mallow in Kankakee County and thismia, originally found in southeastern Cook County and now thought to be extinct. Endemic animals include the Illinois crayfish and Illinois cave amphipod. (5) Habitat degradation caused by human-induced activities such as mining, soil scraping, grazing by livestock, stream channelization, and the introduction of aggressive non-native species that often replace native species. (6) Disruption of ecological processes, such as fires and floods, resulting in community changes. (7) Habitat loss, primarily due to the conversion of the land for agricultural and urban uses. These are the major causes for the loss of native organisms in Illinois, and their impacts will undoubtedly be exacerbated in the near future with an increasing human population.

PLANTS

Rediscovery of blue grama grass in Illinois
L. Phillippe, K. Robertson
Blue grama grass (Bouteloua gracilis), a western species, had been reported from what is now the Savanna Army Depot by Henry S. Pepoon in 1908. The only other known occurrence of this species in Illinois was a collection by former Survey botanist R.A. Evers from Henry County in 1960. It was presumed that the species no longer occurred in Illinois. On the last field trip to Savanna Army Depot in 1996, Survey researchers rediscovered one population of blue grama in sand prairie near a sand blowout area. Based on this rediscovery, the Illinois Endangered Species Protection Board added blue grama grass to the official list of Illinois endangered species in May 1998.

Leafy prairie clover monitoring
B. Molano-Flores
Long-term monitoring of a population of the endangered species leafy prairie clover (Dalea foliosa) on the dolomite prairies of the Midewin National Tallgrass Prairie started this year. Plants will be tagged and mapped, and classified as seedling, juvenile, and adults (i.e., flowering and nonflowering). Future research regarding this species will include reproductive success of the population, genetic diversity of the population, and the effect of fire on reproduction.

FISH AND AQUATIC

Springs of the Driftless Area and Northern Till Plains Region of Illinois
D. Webb, M. Wetzel, L. Phillippe
During 1997, INHS researchers completed a two-year study of the biodiversity, hydrogeology, and water quality of numerous springs located in the Driftless Area and Northern Till Plains Region of Illinois--the third phase of a study that began in 1991. During 1997, surveys of this unique habitat were conducted at over 50 springs located in Carroll, Jo Daviess, Kane, Kendall, Lee, Whiteside, and Winnebago counties. Of particular interest during this current study was monitoring for the presence of agricultural pesticides. Summaries of each phase of this long-term study of springs in Illinois are available via the INHS World Wide Web server at http://www.inhs.uiuc.edu:80/~mjwetzel/SPOIL.hp.html

Chemical and bacterial analyses of Gammarus acherondytes habitat
S. Taylor, D. Webb, S. Panno (Illinois State Geological Survey)
Gammarus acherondytes is a state-endangered troglobite currently being considered for listing as federally endangered. It is known only from streams in six Illinois caves in the Salem Plateau. Earlier studies of Survey researchers identified sedimentation (from agriculture and urbanization), inadequate treatment of human and livestock waste, and agricultural chemicals as potential threats to G. acherondytes. Current research focuses on analyses of the bacterial fauna and water, sediment, and amphipod tissue chemistry within the range of G. acherondytes. Results of these investigations will clarify the nature and extent of these threats, information needed to develop a recovery plan for this amphipod.

Ecology of Hine's emerald dragonfly (Somatochlora hineana)
D. Soluk
Hine's emerald dragonfly is a federally listed endangered species whose range is now restricted to a small portion of the Des Plaines River Valley in Illinois, and Door County, Wisconsin. In both these areas this species is potentially threatened by activities associated with development for industry, tourism, or roadways. The species is found in association with seep areas that receive groundwater flows from dolomitic limestone formations. The exact habitat requirements of both larvae and adults is still very unclear. Such knowledge, and additional information on life-history patterns within the species are crucial for developing plans to protect this species and predict the effects of any particular type of disturbance. Research focuses on life history and patterns of habitat use by both adults and larvae of this species with a particular emphasis on quantitative assessments of the importance of both biotic and abiotic factors in limiting the distribution of Hine's emerald dragonfly.

Native fish new to Illinois
M. Sabaj
The redside dace, Clinostomus elongatus, was recently collected in Illinois for the first time. The minnow was collected in East Fork Raccoon Creek, Winnebago County, a mile from the Wisconsin border. Wisconsin DNR reported redside dace from Raccoon Creek's headwaters in the 1970s, and INHS ichthyologists have long suspected that it would be found in Illinois. Streams in Winnebago County will be resurveyed for the dace and its range in Illinois is likely to be extremely restricted. Populations throughout its range (Great Lakes, upper Ohio, and upper Susquehanna drainages) tend to be isolated and many have disappeared in recent years.

The harlequin darter, endangered in Illinois
R. Steinberg, L. Page, J. Porterfield
Historical records for the harlequin darter, Etheostoma histrio, in Illinois include localities on the Embarras and Wabash rivers. Now this endangered species occurs only in the Wabash River. Protection measures will need to consider the species' reproductive requirements. Research in 1997 and 1998 indicated that eggs are laid in current on large algae- or moss-covered rocks, and that visual signals are used by both sexes. High turbidity that impairs vision or heavy deposits of sediment that bury rocks on the stream bottom (conditions common in Illinois) are likely to have negative impacts on the reproductive success of this species.

BIRDS

Assessment of "essential habitat" for endangered and threatened marsh-nesting bird species
D. Enstrom, M. Ward
The state of Illinois has adopted the term "essential habitat" to describe ". . . the physical and biological environment that is required to maintain viable populations of a listed species in order to ensure the survival and recovery of the species." Delineation of essential habitat assumes good knowledge of what is required. For most species this information is lacking. INHS researchers are developing guidelines for delineating essential habitat for all Illinois endangered and threatened wetland bird species.

Population dynamics of the endangered Yellow-headed Blackbird in northeastern Illinois
M. Ward, D. Enstrom
Researchers are investigating the population dynamics and ecology of the Illinois endangered Yellow-headed Blackbird in northeastern Illinois. As of 1 June 1998 Survey scientists had marked over 60 individuals with colored leg bands and found and monitored over 50 nests. Color-marked birds will provide information regarding the movements of birds within the northeast Illinois landscape as well as information regarding dispersal and migration of birds in the area. This information is vital to the development of a recovery plan for the species in Illinois.

Bell's Vireo ecology
C. Whelan
The Bell's Vireo (Vireo bellii) is an endangered species that is believed to be declining due to reproductive failure caused by brood parasitism. The species breeds in the U.S. from southern California into the upper Midwest. However, little is known of its habitat requirements or its reproductive ecology in the Midwest. This project will determine habitat and reproductive ecology for the species at sites in Will County, Illinois. Preliminary data indicate that in Illinois, brood parasitism may be slight, but nest predation may be severe.

Statewide rare forest bird survey
S. Robinson, J. Morss
During the 1997 field season, researchers completed a census of all larger forest tracts in Illinois in search of rare forest birds that might be candidates for the list of threatened and endangered species. Overall, Survey researchers censused over 120 forest tracts throughout the state. In general, most of the rarest species were either restricted to rare habitat types, such as seasonally flooded swamps (e.g., Brown Creeper), or were found only in the largest forest tracts (i.e., they were area-sensitive: Broad-winged Hawk, Cerulean Warbler, Black-and-white Warbler). Researchers failed to detect populations of Swainson's Warblers and Sharp-shinned Hawks, which suggests that they may be extirpated from the state, or at least no longer breeding regularly. Several species may still be locally common enough that they do not yet need to be listed.

AMPHIBIANS AND REPTILES

Status of the Illinois chorus frog (Pseudacris streckeri illinoensis) in Madison County
J. Tucker, D. Philipp, J. Tucker, G. Packard (Colorado State University)
This is the fourth year of a five-year study of the basic biology of the Illinois chorus frog in Madison County. This study is gathering information necessary to allow successful mitigation of chorus frog habitat loss due to construction of Interstate 255 north into Madison County. Researchers are concentrating on habitat set aside for chorus frogs in Madison County in order to estimate reproductive success and population size in the area. In another study of this species, experiments last year indicated that this frog is not freeze tolerant although other congeners are. Field studies are being conducted to examine actual temperatures experienced by the frogs during winters in central Illinois.

Conservation status of the cricket frog in northern Illinois
J. Petzing, C. Phillips
The cricket frog (Acris crepitans) was once one of the most abundant frogs in the Midwest. Now it is presumed extinct in Ontario and Minnesota and appears to have suffered major population declines in Wisconsin and Michigan. The same fate may be happening in the northern third of Illinois. A statewide survey of 40 randomly chosen historic localities is being conducted to determine the presence and relative abundance of cricket frogs. This survey will clarify the status of the cricket frog in northern Illinois and provide baseline data for future surveys of the cricket frog throughout Illinois.

Population viability of the Illinois endangered silvery salamander
C. Phillips, M. Dreslik, J. Johnson, J. Petzing
Researchers are studying juvenile recruitment and adult breeding population size to assess long-term viability of the endangered silvery salamander at Middle Fork Woods Nature Preserve in Vermilion County. Using a drift fence with pitfall traps encircling the breeding pond, researchers are recording the number and length of juveniles leaving the pond in the summer and of adults entering the pond in the spring. In addition, efforts are under way to determine the age of various length-classes in the adult population. Factors that may negatively affect this population are the health of the smallmouth salamander population and the pond hydrology.

Genetic distinctiveness of the Illinois mud turtle, Kinosternon flavescens spooneri
J. Serb, C. Phillips
Survey scientists are investigating the relationships among populations of the yellow mud turtle,Kinosternon flavescens. Sand prairie relicts in Illinois, Iowa, and Missouri are the habitat of this state endangered turtle. Subspecific status of K. f. spooneri was addressed using mitochondrial DNA sequences. Midwestern populations were not found to be distinct, suggesting that the isolation event separating K. f. spooneri from the nominate subspecies was relatively recent. Although the molecular marker does not differentiate the geographically isolated subspecies, this study may strengthen the argument for federal protection as a Distinct Population Segment under the Endangered Species Act.

Life history and conservation genetics of the state endangered river cooter (Pseudemys concinna)
M. Dreslik, C. Phillips
Recent research on the ecology of a population of river cooters from floodplain lakes in southeastern Gallatin County will be utilized to analyze the genetic integrity of this isolated population. Survey researchers plan to determine the rates of gene flow among the lakes using genetic markers and mark-recapture techniques. A detailed study of the reproductive ecology of this species has begun at the largest of these lakes, Round Pond. The results of this study will allow more precise conservation recommendations for the recovery of this species in Illinois, and will advance the knowledge of turtle life history and genetics.

MAMMALS

Franklin's ground squirrel in east-central Illinois
J. Hofmann
Franklin's ground squirrel is a species of the northern plains whose range includes northern and central Illinois. This species prefers habitats with grasses and forbs of medium height rather than the short grass favored by the thirteen-lined ground squirrel. There are several historic records of Franklin's ground squirrels from east-central Illinois, but very few recent specimens or sightings. Live trapping is being conducted to determine the current distribution of Franklin's ground squirrel in Champaign, Piatt, and Vermilion counties. This survey will contribute to an understanding of the species' conservation status in Illinois.

Fish and Wildlife Ecology

As the landscape of Illinois has changed over the years, the habitat for fish and wildlife populations has generally declined, and management of these resources has become more complex and important. The need for information to make sound decisions has never been as great as it is today. Scientists at the Survey have a long history of research on fish and wildlife and that heritage continues. This research frequently provides information that contributes to the wise management of fish and wildlife resources in Illinois and the nation. The work ranges from conceptual to applied, is extremely diverse, and is conducted throughout the state. Scientists commonly use ecological theory to solve problems in applied management.
Fishing, hunting, and viewing wildlife are important recreational activities in Illinois and the nation and these activities produce immense economic returns by attracting tourists from other states and retaining tourist money in Illinois. Thus, the research of the Survey in supporting fish and wildlife conservation enhances the lives of Illinois citizens by providing much needed recreational and economic opportunities, protecting and diversifying the natural qualities of the landscape in aesthetically pleasing ways, and helping to protect ecosystem functions.
Fisheries research at the Survey is diverse and forms the basis for monitoring, management, and protection of aquatic habitat throughout the state. Work at the Kaskaskia, Ridge Lake, and Sam Parr biological stations deals with issues related to lake, reservoir, and pond fisheries management using ecological theory as the foundation. Thus, the work spans the range from basic to applied research, all of which can be used to modify and improve fisheries management for the benefit of all anglers in Illinois. Studies are being conducted with several cool- and warm-water species that are important sport fishes, including muskellunge, walleye, largemouth bass, crappie, and bluegill. For example, to understand the factors controlling recruitment in these fish populations, information is needed on the various life stages (including larvae, juveniles, and adults) as well as several other trophic levels, such as primary producers, zooplankton, and other invertebrates. As a result, ongoing projects are evaluating trophic dynamics and predator prey interactions in aquatic communities. A variety of management options are being evaluated including stocking strategies and harvest regulations. Recent or ongoing studies examined stocking strategies for muskellunge, walleye, and largemouth bass. These species are expensive to rear in the hatchery, and it is important that strategies be developed to optimize use of this important management tool.
Fish research on the Illinois River conducted out of the River Research Laboratory and the Long Term Research and Monitoring Laboratory in Havana involves monitoring the river's conditions and learning more about the survival and reproduction of aquatic organisms. For example, one research project evaluates the use of navigation dams to benefit plant and animal communities by changing the operation of dams so that undesirable and unnatural fluctuations in water levels are reduced, thus aiding the recovery of native vegetation. Another study focuses upon native mussels in the Illinois River, which once supported a great diversity of mussel species and a commercial industry involved with their harvest. Unfortunately, 70% of the species are currently in jeopardy. A dynamic population model that was developed predicted that it will take over 100 years for populations to recover, even with no commercial exploitation. Many other studies are being conducted including continued evaluation of the status of mussel populations in the Illinois River, the influence of commercial barge traffic on the Illinois River ecosystem, comparison of invertebrate communities on dredge spoil with those on natural substrates, and investigation of the use of moist-soil management units by fish.
Research conducted by scientists out of Champaign focuses upon the potential effects of increased commercial navigation on the mortality of fishes in the Mississippi and Illinois rivers. This research has shown that towboat and barge traffic has the potential to directly increase the mortality of fishes in the main channel of the Mississippi River. Another research project in this area involves monitoring the abundance and distribution of fishes in Pool 26 of the Mississippi River and the lower Illinois River. Researchers found that a diverse assemblage of larval, juvenile, and adult fishes use the main channel and that the distribution of some large fishes may be influenced by navigation locks and dams. Other aspects of this research will explore indirect effects of commercial navigation on fishes, river food-web interactions, and recruitment patterns of fish.
The Survey is also deeply involved in studying fish and fishing at many other locations throughout the state. One example is the survey of sportfishing in Lake Michigan. This survey was conducted to provide reliable estimates of sportfishing activity, sportfish harvest expenditures, and the quality and distribution of sportfishing. Estimated expenditures for boats, motors, trailers, fishing gear, and automobile gas were $10 million. The value of the sportfishing harvest was approximately $1.35 million. Similarly, creel surveys have been conducted on Illinois impoundments. Since 1987, INHS scientists have conducted angler surveys on a total of 68 state-managed lakes to estimate the total fishing effort; the species, numbers, and weight of fish harvested and released; and the species targeted by anglers at these lakes. The data collected are directly applicable in the management of these lakes, especially in evaluating the effects of short-term management changes and supplemental stocking on yield and catch per angling effort and the impact of sportfishing intensity on the resource. Yellow perch and their requirements are another area of research. Yellow perch have had nine consecutive years of poor recruitment in Lake Michigan, and research is under way to help biologists better understand the fundamental requirements of yellow perch and the influence of other factors on their survival and reproduction. These research findings will be useful in making management decisions.
Wildlife research in the Survey also is diverse, encompassing a wide variety of studies about game and nongame birds, mammals, turtles, snakes, invertebrates and their habitats. At the Forbes Biological Station near Havana, scientists continue a long-standing tradition of waterfowl and wetland research on the Illinois River. Illinois has lost 90% of its presettlement wetlands through drainage and development. The quality of many of the remaining wetlands has been affected by sedimentation and other anthropomorphic factors. Because of these changes, many native wildlife populations have declined, some have completely disappeared, while some have adapted well to the changes. Many non-native species have become abundant and occupied the niches of native species or filled a new niche. As a result of the direct and indirect human influences on the Illinois River and the habitats it provides for wildlife, much research has focused upon the interaction of habitat quality and quantity with populations of wildlife. Populations of waterfowl and other birds migrating through the Illinois River are monitored each year (for the past 50 years) through aerial censuses by Survey scientists. These data provide a useful index to waterfowl populations in the region and are a useful indicator of wetland habitat quality and quantity remaining in the Illinois River system. Recently completed research has greatly improved our knowledge of how Wood Ducks use natural cavities and what influences their nesting success. Investigators are also developing a census technique for breeding Wood Ducks through the use of helicopters. Another recently initiated project involves studying the nesting and brood survival of Mallards in Illinois using radio transmitters. This is the first investigation of Mallards in Illinois, where their nesting has become more commonplace in the past decade.
Survey research on the ecology of large mammals focuses on the influence of humans on habitats and populations. The general question being pursued is How can we sustain populations of large mammals in a landscape that is heavily exploited for human needs that subject these mammals to hunting, control efforts, altered competitive relationships, or loss of natural predators? The influence of human activity impacts every characteristic of these species' life histories and these impacts can be either positive or negative to humans and ecosystems. Discerning the net effect is important. Wildlife research at the Survey crosses topical categories, and thus much of the work involving wildlife is reported under restoration ecology. Nevertheless, these research efforts lead the nation in creating the foundation for management and protection of wild animals in grasslands, savannas, forests, and wetlands. For example, research projects at the Survey focus on reproduction and survival of songbirds in forests, savannas and grasslands; the ecological requirements of the red-eared slider turtle and other turtles; reproductive success in salamanders; reproductive behavior of red-winged blackbirds; composition and ecological distribution of aquatic macroinvertebrate communities; conservation status of crayfish; ecological contaminants and wildlife; and testing of candidate shot for use in hunting. Fish and wildlife research at the Natural History Survey is extraordinary in its diversity and breadth and directly assists in the management of these important resources.

AQUATIC ECOLOGY

Conservation status of crayfishes of the United States and Canada
C. Taylor
Numerous North American crayfish species are known to have extremely small ranges and are vulnerable to decimation and possible extinction. Recent work done in collaboration with crayfish researchers from around the United States has suggested that over 45% of the crayfish fauna of the U.S. and Canada is in need of protection and/or monitoring. In 1996 a manuscript listing conservation status and state distributions for all 338 crayfish species known from the U.S. and Canada was published. Efforts are now directed towards maintaining a computer database of state distributions and up-to-date conservation statuses of North American crayfishes.

Macroinvertebrate and fish assemblages in Louisiana streams
R. DeWalt
Louisiana has no biological criteria for rating stream health. Since 1991 the USEPA and the Louisiana Department of Environmental Quality have funded sampling of least-impacted streams in four freshwater ecoregions (ecologically similar regions) across Louisiana. Both macroinvertebrate and fish assemblages demonstrate that regions are statistically different and warrant ecoregion-specific criteria. Ecoregions appear to be a viable framework for minimizing variation of faunal communities in streams of Louisiana.

Oviposition site choice
W. Resetarits
Many processes may affect the structure and species composition of aquatic communities. One of the least understood is the role of oviposition site choice in the colonization of aquatic habitats. A large component of the fauna in many aquatic systems is the result of repeated colonization by aquatic insects and amphibians; thus, selectivity by ovipositing females has the potential to dramatically affect the structure and function of aquatic communities. Both experimental studies and mathematical modeling are being used to study the role of oviposition site choice in aquatic systems.

Top predators regulate both rooted and pelagic primary producers through crayfish assemblages in shallow aquatic systems
T. Smith, D.Wahl
The trophic cascade hypothesis (TCH) states that top predators elicit "cascading" effects that move down the food chain and eventually affect primary producer abundance. Assumptions of this model are widely violated in complex ecosystems. Pond habitats contain many such violations, yet Survey researchers have shown that large fish in ponds can regulate both rooted plants and phytoplankton by consuming crayfish. However, in contrast to the predictions of TCH, effects of predatory fish through crayfish appear to depend on the reduction of nutrient cycling by crayfish into the water column. Results of this research mirror predictions of top predator effects on planktivores in ponds.

Dormancy in Oneida Lake Daphnia
C. Cáceres
Many populations of freshwater zooplankton produce long-lived diapausing eggs which accumulate in lake sediments in large numbers. In Oneida Lake, New York, the eggs of two species of the suspension-feeding crustacean Daphnia reach densities of over 104 eggs/m². Sedimentation rates obtained by 210Pb dating suggest that these eggs can remain viable for over 125 years and that these two Daphnia populations have persisted in this system for over 200 years. Prior research has demonstrated a difference between the benthic-pelagic link of the two species. Although the two species reach similar population densities in the water column, fewer D. galeata mendotae females switch to the production of the dormant eggs than D. pulicaria. This results in fewer diapausing eggs being produced and stored by D. galeata mendotae, which results in lower emergence rates. Current research focuses on the cues required to initiate and terminate dormancy in these two populations.

Stonefly diets and habitat use
K. Edly, S. Kohler
Predaceous stoneflies are important links in stream food webs as consumers of other bottom-dwelling invertebrates and as a source of food for fish. Habitat and diet selection of two common stoneflies are being studied in midwestern streams with contrasting prey communities and in laboratory experiments. These studies will identify prey species that appear especially vulnerable (or invulnerable) to stonefly predation, and mechanisms responsible for variation in prey vulnerability. Results will be used to help assess effects of stoneflies on populations of their prey.

Impacts of dredging on invertebrates
K. Blodgett, K. Stevenson, R. Sparks
Portions of the Illinois River are hydraulically dredged to maintain a nine-foot channel for commercial navigation. Dredged material is often sidecast along the bankline, covering more natural substrates and reducing habitat diversity. Survey scientists are comparing invertebrate communities on submerged dredge spoil with those on natural substrates and monitoring changes over time. If there are detectable adverse impacts to invertebrates, researchers will recommend changes in dredging procedures, including spoil placement, to reduce these impacts.

Status of mussel populations in the Illinois River
S. Whitney, K. Blodgett, R. Sparks
Researchers resurveyed areas of the Illinois River that INHS biologist Dr. William Starrett had surveyed 30 years ago. Results indicate that mussels are recolonizing the upper Illinois River near Chicago, where all mussels had been eliminated by gross pollution. Starrett had taken no living mussels in the same reaches where scientists found healthy mussels. Overall, however, there has been a net decline. In the middle and lower Illinois River, declines appear to be associated with periodic heavy zebra mussel infestations and episodes of poor water and sediment quality.

AMPHIBIAN AND REPTILIAN ECOLOGY

Habitat use and hibernacula of snakes
L. Keller, R. Larimore, E. Heske, C. Phillips
Using radiotelemetry, Survey researchers are monitoring relative use of forest, open fields, and forest-field edges by black rat snakes, fox snakes, and blue racers. Little is known about where these snakes hibernate in agricultural regions of the Midwest, and thus researchers are tracking snakes to their hibernacula in the fall. This information will help determine types of hibernation sites critical for the conservation of snakes and identify species of snakes that may be predators of songbird nests in different habitats.

Survival and hatching success of marbled salamander eggs
J. Petzing, C. Phillips, B. Sharp
Most salamanders in the genus Ambystoma breed in the spring in newly filled ponds, but the marbled salamander lays its eggs in the fall in leaf litter within dry pond basins and relies on early winter rains to inundate the eggs. This study focused on the ability of the eggs to withstand desiccation and cold temperatures during dry winters when breeding ponds fail to fill. Over 80% of marbled salamander eggs hatched after six months of desiccation and sub-zero temperatures. This reproductive strategy enables marbled salamander hatchlings to avoid intense competition for resources with other salamander species and to metamorphose before the pond dries up.

Modeling turtle growth using mark/recapture methods
M. Dreslik
The amount of time it takes an organism to grow to sexual maturity strongly influences its lifetime fitness and reproductive success; therefore, precise knowledge of growth is integral to understanding life history. Numerous growth models explain the relationship between size and age, but often the organism's age is unknown. Age can be removed as a factor by reexpressing the models with size at first and last capture. Such models are being tested using long-term data sets on two species of freshwater turtles from Illinois, the slider, Trachemys scripta, and the river cooter, Pseudemys concinna.

Basking habitat of freshwater turtle species
A. Kuhns, M. Dreslik
Thermoregulation by basking is prevalent in turtles as a mode of increasing metabolism for assimilating nutrients, meeting energetic demands, and enhancing healing. Survey scientists are investigating whether juvenile and adult turtles bask in different habitats at a floodplain lake in southeastern Gallatin County. Results of this study will increase researchers' understanding of age-specific habitat requirements, an area that has been neglected in vertebrate biology.

Ontogenetic sexual dimorphism in the turtle shell
M. Dreslik
How body size relates to reproductive success and fitness is one of the most actively studied aspects of life history. In turtles it has been demonstrated that egg size is constrained by the diameter of the pelvic aperture. Data from a long-term study on the slider, Trachemys scripta, and the river cooter, Pseudemys concinna, have revealed a significant dimorphism in shell ontogeny between male and female turtles. Males tend to be streamlined in shape while females are more domed. This presumably occurs because of requirements for housing eggs, therefore the shell shape may constrain clutch and/or egg size.

The effects of timing of nesting on nest temperatures and sex ratios in painted turtles Chrysemys picta
C. Backe
Nest temperature is the most important factor determining the sex ratio of turtles. However, little information is available on how the timing of nesting affects nest temperature and sex ratios. This research includes recording painted turtle nest temperatures throughout the nesting season at a site in central Illinois. Painted turtle eggs hatch in the fall, but hatchlings remain in the nest until the following spring. To investigate whether metabolic heat from the hatchling turtles affects nest temperature, temperatures of nest cavities and empty cavities are recorded throughout the winter. Mark/recapture data on adults to determine population structure are also being recorded.

Amphibian species diversity
W. Resetarits, J. Fauth (College of Charleston)
An important goal of ecology is identifying and understanding the processes that generate and maintain species diversity. Understanding these processes is also critical to the preservation of biodiversity. Research continues on processes affecting frog species diversity in seasonal wetlands in the Sandhills and Coastal Plain regions of the Southeast. These natural wetlands support the most diverse local assemblages of frogs outside the tropics. Experiments in artificial ponds, field sampling, and field experiments are being combined to develop and test an explanatory model of frog species diversity in these seasonal wetlands.

Brook trout-spring salamander interactions
W. Resetarits
The broad coexistence of stream-dwelling salamanders with predatory fish is a perplexing question in light of the almost total exclusion of pond-dwelling salamanders by predatory fish. This project focuses specifically on the interactions between spring salamanders and brook trout. The goal of this project is to determine (and quantify) the specific factors that contribute to the maintenance and dynamics of spring salamander populations in streams containing brook trout, and to use this as a model system for studying complex mechanisms of species coexistence under asymmetric competition.

Ecological studies of the red-eared turtle Trachemys scripta elegans
J. Tucker, F. Janzen (Iowa State University)
Researchers are tracking emergence patterns among hatchling red-eared sliders to examine environmental cues used by overwintering hatchling sliders to time their emergence from nests in the spring. Another study is looking at reproductive efforts of Trachemys scripta elegans in habitats bordering the lower Illinois River. The primary focus is on annual and seasonal variation in reproduction in relation to flooding. Research also includes experimental release of 2,000 hatchling sliders to examine the impact of predation on recruitment and phenotypes of sliders by replicate releases. An additional study examines egg size variation associated with oviductal position in the red-eared slider turtle.

BIRD ECOLOGY

Population ecology of Prothonotary Warblers
J. Hoover
Prothonotary Warblers are one of the most abundant species nesting in swamp forests of Illinois. Unlike most warblers, they nest in cavities of trees located in shallow water, which makes them amenable to studies using nest boxes. A study of over 300 marked pairs of birds using over 1,200 nest boxes has shown that water levels determine nesting success. Nest cavities located in water of at least a foot in depth are much more likely to succeed than nest cavities located over shallow water, most of which are destroyed by raccoons. Prothonotary Warblers are heavily parasitized by Brown-headed Cowbirds, but have no defenses against the brood parasites. In contrast, experiments have shown that the warblers respond adaptively to nest predation by avoiding areas in which few of their young have fledged. Changing water levels and increasing parasitism may pose severe long-term threats to this species by reducing nesting success.

Area and edge effects on grassland birds
J. Newton, E. Heske, D. Rosenblatt
Using artificial nests baited with quail and finch eggs, researchers are evaluating rates of nest predation on songbird nests in grassland patches of different sizes (area effects), and at different distances from forest edges or mowed trails (edge effects). This information will help identify threshold sizes for management units of grassland and shrubby fields to best benefit nesting songbirds. It will also indicate if any area effects found are due to predators that venture out into open fields for a limited distance from forested habitat, or that use features like trails and treelines as travel routes.

Bird inventory of the Kaskaskia River corridor
S. Robinson
The Kaskaskia River corridor between Carlyle and Fayetteville contains the largest single forest tract in Illinois and in aggregate contains over 30,000 acres of mostly floodplain forest. As such, it provides an ideal opportunity to determine if birds are more abundant and nesting success is higher in the interior of the forest than along the edge. A field crew led by Stavros Daniels located more than 400 nests in 1997 and the data show that most species experienced much lower rates of nest predation and parasitism by Brown-headed Cowbirds in the interior of the forest than along the edge. This area contains the largest population of Cerulean Warblers and, probably, American Redstarts in the state as well as very high populations of such species as the Red-shouldered Hawk, Yellow-billed Cuckoo, Prothonotary Warbler, and Red-headed Woodpecker. The combination of high nesting success and high populations of many forest species suggest that this forest may be a source of birds available to recolonize smaller woodlots in the state in which nesting success is much lower.

Community and population ecology of birds in Neotropical forests
J. Brawn, S.K. Robinson, W.D. Robinson
Understanding the ecology of migratory and resident birds in Neotropical forests is vital to their conservation. Spatial and temporal variation in community structure as well as demographic parameters such as survival rates and population size are central issues. These questions are being assessed in a long-term study of avian ecology in the lowland forests of central Panama. A large mark-recapture dataset has been established along with a comprehensive survey of community structure within a 100 ha census plot. For migratory birds, results will complement and reinforce studies of reproductive ecology in Illinois.

The dawn chorus of breeding birds
R. Larkin, R. Diehl, S. Droho (University of Illinois)
Birds are often counted by listening to their songs, as reflected in the title of Rachael Carson's classic book Silent Spring. To aid such census work, modern sound recording equipment was deployed in two Illinois habitats to record bird sounds starting in the before-dawn darkness through midmorning. Preliminary results indicate that birds that reside year-round in Illinois may sing at different times in May after migrants have returned from the tropics than they do before the migrants have arrived.

Eastern Bluebird population study
S. Havera
The 18th consecutive year of monitoring the bluebird population on a 24-hectare study area in Fulton County was completed. Eastern Bluebird population numbers have been declining regionally in recent years principally because of decreasing nesting habitat. No scientific studies of nesting populations of bluebirds have been conducted in west-central Illinois since 1935. This study evaluates the reproductive success, territoriality, survival, and homing of Eastern Bluebirds. In 1997, 58 bluebird houses were monitored. The bluebird nesting season began on 9 April and lasted until 18 August. Eleven nests (one egg laid) occurred and 9 (82%) successfully fledged young. Five of the 9 (56%) adults examined and nesting on the area were previously banded and returned.

Effects of different kinds of edges and shrubland size on nesting success of birds
S. Robinson, J.D. Brawn, S. Morse, E. Heske
Many species of birds that nest along edges and in early successional shrublands have been experiencing population declines as severe as those documented for birds of forests. During the 1997 field season, Survey researchers continued measuring the nesting success of birds along different kinds of edges and in shrublands of different sizes to help develop management recommendations that might help reverse these population trends. Researchers found and monitored over 750 nests and determined that field size and edge type have relatively small effects on nesting success in the heavily agricultural landscapes of east-central Illinois. Nesting success was low in all fields and edges for most species because of very high rates of nest predation and, to a lesser extent, brood parasitism by Brown-headed Cowbirds. Management practices that maximize habitat heterogeneity and edge density may not provide safe nesting conditions for birds that require edges and shrublands. Nevertheless, some species (Field Sparrow and Eastern Towee) appear to have adaptations such as very long nesting seasons, and other species (Gray Catbird and Baltimore Oriole) have the ability to recognize and reject cowbird eggs, which enables them to produce young even in areas with abundant nest predators and cowbirds.

Ecology of Eastern Wild Turkeys in Illinois
P. Hubert, T. Van Deelen, P. Brown, R. Warner
Since 1959, efforts to restore populations of Eastern Wild Turkeys to Illinois have been largely successful. Unfortunately, populations in some Illinois counties have failed to thrive despite apparently adequate habitat and repeated releases of turkeys from wild populations that were known to be robust. Researchers are using radiotelemetry to compare hen survival and poult recruitment in two representative counties that have similar habitat but different records of turkey restoration success. In addition, scientists are constructing a statewide model of turkey habitat using remote sensing data and turkey sightings reported by deer hunters from 1993 to 1997. The data will enable Illinois Department of Natural Resources managers to better evaluate turkey restoration relative to past efforts and available habitat.

Furbearer predation on shrub-nesting bird nests
J. Newton, T. Van Deelen, E. Heske
Nest predation may be an important factor in the decline of migratory birds that nest in shrubs in natural areas of Illinois. Several species of Illinois mammals (raccoons, opossums, gray foxes, gray squirrels, and red squirrels) have been suggested as potential predators of shrub-layer nests because of their tree climbing abilities and their omnivorous/carnivorous food habits. Nests in edge habitats may be especially vulnerable due to the foraging habits of mammalian predators. This project used automatically triggered cameras and artificial nests to document the nest predation rates of Illinois mammals relative to shrub lands, forests, and shrub land/forest edges. Results suggested that raccoons were the chief predators of shrub nest, although researchers also recorded predation from mice, blue jays, and tufted titmice. Also, predation rates did not differ with respect to a nest's placement in oldfield, forest, or forest edge vegetation.

Landscape factors influencing the nesting success of the Acadian Flycatcher
L. Chapa, S. Robinson
The Acadian Flycatcher is one of the most abundant and widespread breeding songbirds in the wetter forests of Illinois. Because of its abundance and relatively conspicuous nests, it is ideal for comparing nesting success across sites embedded in contrasting landscapes, such as rural grasslands versus rural crop fields. Data from 1997 revealed the exciting presence of two sites with very low rates of nest predation and brood parasitism by Brown-headed Cowbirds. One of these sites was in the interior of the extensive floodplain forests of the Kaskaskia River corridor southeast of St. Louis and the other was in the heart of the Eastern Shawnee Hills of southern Illinois, a landscape in which agriculture takes the form of rural grasslands rather than the row crops that dominate the rest of the state. These results provide hope that there may be areas within Illinois that have high nesting success of at least some migratory songbirds.

Woodland bird populations
C. Whelan
Many bird species are believed to be suffering population declines due reproductive failure related to brood parasitism by the Brown- headed Cowbird and nest predation. A study during 1992- 1997 focused on the reproductive ecology of the Wood Thrush (Hylocichla mustelina) and American Robin (Turdus migratorius) to learn how these processes differentially affected offspring production in the two species. Both species lost many potential offspring (eggs and nestlings) to predators, but Wood Thrush, the only species of the two to suffer brood parasitism, tended to have lower production than the robin.

Mating behavior of Redwinged Blackbirds
D. Enstrom, K. Yasukawa (Beloit College, WI)
The effect of color on the mating behavior of Redwinged Blackbirds is being assessed in both field and lab experiments. In field experiments red wing patches of males are being manipulated in order to assess the effect of color on male aggression, pairing success, and mating success. In 1998 researchers are focusing on female assessment of male symmetry.

Birds and removal of invasive plants
C. Whelan
A problem for land managers and conservationists is the invasion of forests and woodlands by nonindigenous, invasive, woody plant species. Prime examples include buckthorn (Rhamnus cathartica) and honeysuckle (Lonicera mackii). This project, conducted at the Morton Arboretum, Lisle, Illinois, compares the use by forest birds of a wooded area cleared of woody understory plants with that documented over the previous six years before clearing. The project is currently ongoing, but preliminary data indicate that several bird species are no longer present in the cleared area, although they persisted in nearby uncleared areas.

Birds nesting in invasive plants
C. Whelan
Birds often nest in exotic plant species because they are the only suitable plants available after they invade remnant habitats. INHS staff determined how nesting in exotic species affected nest outcome when compared to nesting in indigenous plant species. Results indicate reduced nest success for nests placed in exotic substrates, possibly because the available exotics lacked thorns, reduced average nest height, and presented nest predators with sturdier branches. Each of these increases predator encounter rates with attempted nests. The work indicates the need for restoration of native plant species.

WATERFOWL

The nesting biology of Mallards in Illinois
A. Yetter, C. Hine, M. Georgi, L. Anderson, S. Havera
In recent years, nesting Mallards have become more common in Illinois; however, their nesting biology has never been investigated. A three-year study was initiated in the spring of 1998 to collect information on the nesting biology and brood survival of Mallards nesting in the Illinois River valley. Forty wild hen Mallards were captured and fitted with radio transmitters on a public and a private area in the LaGrange Pool. These females were then monitored for approximately four months to determine their nesting habits and success.

Status/management of Illinois waterfowl
S. Havera, K. Roat, M. Georgi, C. Hine, A. Yetter, L. Anderson
This project culminated in a book manuscript of approximately 1,500 pages, and the publication process is under way. A variety of topics relating to waterfowl were investigated with major emphasis placed on wetland habitat, food habits analyses, population analyses, banding results, harvest information, historical records and regulations, private duck clubs, Canada Geese, nesting information, and waterfowl management. This thorough compendium of information on the rich waterfowl tradition in Illinois will be a welcome addition to the literature for those citizens with a special interest in waterfowl as well as for biologists and natural resource managers throughout the Mississippi Flyway. A companion field guide is also nearing publication.

Toxicity of ingested shot in waterfowl
J. Levengood, G. Sanderson, W. Anderson, P. Brown, G. Foley, J. Seets
There is continued worldwide interest in alternatives to steel shot for waterfowl hunting and other shooting applications. Studies conducted by Survey researchers indicated that zinc shot currently used as a nontoxic substitute for lead shot in parts of Europe was toxic to Mallards. A study was conducted to examine the effects of diet in mitigating the toxicity of zinc to Mallards. Results have indicated that diets varying in protein, calcium, phosphorus, hardness of food items, and soil availability had little effect on zinc intoxication, contrasting previous studies of lead poisoning in ducks.

Wood Duck nesting behavior at Nauvoo
C. Hine, A. Yetter, S. Havera
In 1984, 80 Wood Duck boxes were erected along the Mississippi River near Nauvoo. Subsequently, the number of boxes was reduced to 58 because of the 1993 flood. The high density of nest boxes contrasts with the density of natural nesting cavities--about 1 per acre. The number of females in the boxes increased from 46 in 1984 to 74 in 1986 and peaked at 95 females in 1992. Intraspecific strife became evident in Wood Duck females in 1985. From 1984 through 1997, conflicts among female Wood Ducks resulted in 71 females with head injuries and 60 fatalities resulting from head wounds. There is a strong relationship between the number of nesting Wood Duck pairs at the study area in a particular year and the number of injured and dead females.

Aerial inventories of waterfowl populations
M. Georgi, S. Havera
During 1997-1998, aerial inventories of waterfowl numbers, species composition, and distribution were conducted throughout Illinois during fall, winter, and spring migrations. This was the 50th consecutive fall migration that waterfowl have been aerially surveyed in the Illinois and Mississippi river valleys. In the Illinois River valley, the 1997 fall peak number of Mallards (406,365), the most common migrant waterfowl species in Illinois, was 61% higher than the 1996 peak, and 28% higher than the 1992-1996 five-year average. In the Mississippi River valley, the fall peak number of Mallards (156,300) was 27% higher than the number inventoried in 1996 and 21% higher than the five-year average. Peak numbers of total ducks inventoried in the Illinois Valley were 62% higher than in 1996 and 34% higher than the five-year average; in the Mississippi Valley total duck peak numbers were up 35% over 1996 but down 28% from the five-year average. Although continental populations of many species of waterfowl are increasing, the quality and quantity of habitat in the Illinois and Mississippi river valleys continues to be a factor in the numbers and distributions of waterfowl in Illinois.

Aerial surveys of breeding Wood Ducks
A. Yetter, C. Hine, S. Havera
Currently no adequate inventory methods, other than labor-intensive monitoring of natural cavities, exist to estimate the size of breeding Wood Duck populations in Illinois and the Midwest. Wood Ducks inhabit densely forested areas and are difficult to observe. Therefore, Survey researchers initiated a three-year study utilizing aerial line transect methodology and helicopters to estimate breeding Wood Duck populations in Illinois River bottomland forests. Aerial survey data from 1997 indicated densities of 0.04-0.09 breeding Wood Duck pairs per hectare of bottomland forest. Aerial survey densities observed in 1997 were similar to actual Wood Duck nest densities observed in natural cavities during the springs of 1994 and 1995. Surveys were repeated in spring 1998 to compare Wood Duck densities derived from line transect methodology to wood duck densities observed utilizing natural cavities in bottomland forests.

Canada Goose migrations
R. Larkin
Each year upwards of a million interior Canada Geese migrate from Canada to spend the winter in Illinois. Observations on radar show the magnitude and precise route of this migration, much of which takes place on one or two days in December. Flying very straight, the flocks of up to 1,600 geese follow one another with great accuracy but seem to ignore landmarks along the way, continuing their migration after dusk. The geese are usually blown east of their destination and must later fly west to reach their wintering grounds.

Contaminants in Canada Geese
J. Levengood, S. Ross (Illinois Deptartment of Agriculture), M. Stahl (University of Illinois), V. Beasley (University of Illinois)
Populations of Canada Geese have increased to nuisance levels in many metropolitan areas. To help reduce burgeoning goose populations, some states have initiated or proposed programs to process resident Canada Geese as a protein source for underprivileged humans. Researchers assayed concentrations of organochlorine pesticides and polychlorinated biphenyls in tissues of giant Canada Geese collected in the Chicago area to help assess risks to humans consuming goose flesh. Of 18 chlorinated hydrocarbons assayed, only DDE, dieldrin, heptachlor epoxide, and 1 PCB congener were present in detectable concentrations. Interpretation of these results relative to government guidelines for food safety is continuing.

Heavy metals in ducks and waterfowl habitat components
J. Levengood, P. Brown
Smelting, mining, refining, and various industrial processes have resulted in the release of large amounts of heavy metals into the environment. The presence of these elements threatens environmental health, subject to their concentration and availability. Survey researchers initiated a study to examine the availability of metals to waterfowl using a managed impoundment located along the Illinois River. This area has elevated concentrations of heavy metals as a result of past smelting and dredging operations. Concentrations of selected metals in Mallard and Wood Duck tissues as well as in habitat components, such as seeds, water, and sediments, are being examined.

Lead shot exposure to ducks utilizing the Mississippi Flyway
S. Havera, W. Anderson
The last survey on the prevalence of ingested shot in ducks throughout the Mississippi Flyway was conducted from 1977 to 1979. The nationwide implementation of the nontoxic shot program was begun in 1991. This study investigates the degree to which ingested nontoxic shot has replaced ingested lead shot in dabbling and diving ducks throughout the Mississippi Flyway during the 1996 and 1997 hunting seasons. During each of the 1996 and 1997 hunting seasons, approximately 9,000 gizzards were collected throughout the flyway and forwarded to the Survey for analyses.

MAMMALIAN ECOLOGY

Small mammals in managed grasslands
E. Heske
Management practices at Prairie Ridge State Natural Area in Jasper County, such as the planting and maintenance of blocks of different types of vegetation, undoubtedly affect the dispersion, abundance, and productivity of populations of small mammals. An abundant supply of small mammals, in addition to extensive areas of grassland and wetland habitat suitable for roosting and nesting sites, is necessary for successful overwintering and nesting of raptors such as Northern Harriers and Short-eared Owls. This study is monitoring small-mammal populations in different types of vegetation at Prairie Ridge to determine how management of grasslands for Greater Prairie Chickens also can be used to promote a stable and abundant prey base to benefit endangered raptors.

Deer herbivory and the composition of bottomland forests
T. Van Deelen, D. Bowman, A. Plocher
During the last 15 to 20 years, populations of white-tailed deer have increased dramatically in many areas of the Midwest including Illinois. In the agricultural counties of central Illinois, deer from throughout the region migrate to remnant forests patches and isolated woodlots for overwinter survival because these areas provide the only permanent cover and available browse once the crops are harvested. Herbivory associated with unusually high concentrations of overwintering deer may impact the species composition of central Illinois forests because deer are selective browsers, preferentially eating some species and avoiding others. This project is using deer exclosures to estimate the impacts of deer browsing on the bottomland forests of Allerton Park, an important wintering area for deer in east-central Illinois. In addition it will provide guidance for the management of browse-sensitive plant communities.

Deer in the urban ecosystem
D. Etter, T. Van Deelen, R. Warner
Recent reviews of the impacts of high white-tailed deer (Odocoileus virginianus) populations on forest ecosystems in the eastern and midwestern United States present a convincing case that, at high densities, deer act as keystone herbivores. Intense herbivory by deer may cause changes in the distribution and abundance of other plant and animal species and modification of community structure through altered competitive relationships and cascading trophic effects. These community-level effects are exacerbated in urban/suburban settings because of the fragmentary nature of insular natural areas, the diversity of agencies and private groups with management responsibility, lack of sport hunting as a management tool, and the controversy surrounding deer management programs. Using radiotelemetry and deer removal statistics from the Chicago area, researchers are documenting patterns of survival, reproduction, and behavior of deer in urban ecosystems. The volume and quality of this data set is unique among the published literature on white-tailed deer and promises to be a benchmark in the scientific management of urban deer.

Dispersion of gray and fox squirrels
D. Rosenblatt, E. Heske
In east-central Illinois, gray squirrels now occur primarily in a few extensive forest tracts and in some urban areas, whereas fox squirrels are dominant in rural woodlots. Biological mechanisms to explain the different distributions of these species are being evaluated using experimental translocations and radiotelemetry. Are gray squirrels absent from most rural woodlots in this area because these small forest remnants are unsuitable habitat, because fox squirrels competitively exclude grays from them, or because gray squirrels are poorer cross-country dispersers than fox squirrels? Results of this study will add to researchers' understanding of how habitat fragmentation affects wildlife.

Fox and coyote ecology in central Illinois
T. Gosselink, T. Van Deelen, R. Warner, P. Mankin
Since coyotes are known to be intolerant of red foxes throughout their range, conservationists in Illinois are concerned that red fox populations have declined in response to a dramatic increase in coyote populations since the 1950s. Scientists are using radiotelemetry to study the behavior and survival of sympatric red foxes and coyotes relative to human influences on the landscape of central Illinois. The goals of this project are to measure the degree to which foxes and coyotes use overlapping habitats and to estimate the impact of coyote aggression on fox mortality. This project was initiated in 1996 and has resulted in the capture and radio collaring of 90 foxes and 38 coyotes. Capture data and radiotelemetry observations suggest that foxes may persist in some areas because they are more tolerant of human disturbance, but areas of intense human use are associated with severe pup mortality due to mange and automobiles.

Habitat use by raccoons and opossums
E. Heske, D. Rosenblatt
Raccoons and opossums are extremely abundant in many areas of Illinois, and can have a major local impact on nests of songbirds and other prey species, such as amphibians and turtles. This study is using radiotelemetry to track the movements and habitat use of these medium-sized, generalist predators to learn how they forage. In what habitats do raccoons and opossums concentrate their activity? How do landscape features such as forest-field edges affect their movements? The results may help to identify management practices that can reduce predator activity in some areas and benefit certain prey species.

ECOLOGICAL MODELING

Dynamic trophic interactions in ecosystems
R. Herendeen
Trophic cascade and top-down:bottom-up hypotheses are used to describe and predict how perturbing one organism affects the others in an ecosystem. A quantitative general theory was developed that predicts all features of trophic cascades and top-down:bottom up effects, and covers intermediate cases as well. Specific quantitative predictions agreed with known results from the Lotka-Volterra theory of predator-prey relations. This method, however, is based on comparison of systems at steady state, yet most experimental and real ecosystems are in continual dynamic change. The theory has been extended to include dynamic systems, and testing against recently available data is being done.

Individual-based modeling of walleye populations in Illinois impoundments
T. Galarowicz (University of Illinois), R. Herendeen, D. Wahl
Overall survival of walleye to fishable sizes depends strongly on the condition of juveniles at the end of the first growing season. Several processes that determine a larval fish's first-summer survival and growth are known to be size dependent, such as susceptibility to predation. Predicting the numbers and condition of surviving juveniles therefore requires a highly disaggregated modeling approach that keeps track of many different size classes. Researchers continue building such an individual-based model to better predict the consequences of management options on populations, calibrating it with results from laboratory and field experiments at the Kaskaskia Field Station.

Population models for native mussels
K. Blodgett, J. Stoeckel, R. Sparks
Native freshwater mussels are among the most threatened groups of organisms in the world. The U.S. once had more species of freshwater pearly mussels (Unionacea) than any other nation, but today 70% of the species remaining in the U.S. are in jeopardy. In order to better manage native mussels, Survey researchers developed a dynamic population model. Results indicate that it will take over a century for mussel beds to recover to an equilibrium population size, even if harvest ceases. Model results are being used to support bans on commercial harvest in the Illinois and upper Mississippi rivers.

Predictive model of juvenile gizzard shad abundance for Lake Shelbyville, Illinois
T. Smith, D. Wahl
Gizzard shad dominate the fish communities and are the primary diet item of most piscivores in midwestern and southern reservoirs in the continental U.S. Survey scientists recently devised a model to predict the annual abundance of gizzard shad from characteristics of the spring water-level rises. For the past three years, this model has provided successful a priori predictions of juvenile gizzard shad abundance. These results suggest the potential utility of water-level manipulations as a tool to regulate gizzard shad and fish assemblages in systems with managed flows.

Evaluation of esocid bioenergetic model
S. Chipps, L. Einfalt, D. Wahl
Usefulness of bioenergetic models depends on accuracy of model output. Despite this, few models have been corroborated using independent field or laboratory data. Independent evaluations of an esocid bioenergetic model revealed poor fits between model output and observed data. The model overestimated food consumption and underestimated growth for esocids in field and laboratory evaluations. Accuracy of model output varied with water temperature and esocid growth rate. At low water temperatures, the model performed poorly. Accuracy of model output increased as growth rate of esocids increased. Researchers concluded that errors in bioenergetic parameters have less influence on model output when high growth rates are used as input.

FISH ECOLOGY

Developmental genetics of sunfish hybrids
D. Philipp, R. Fields, J. Claussen, M. Fields, J. Epifanio (Michigan State University)
Among the sunfishes, hybridization between species is a common event. This work studies the pattern of gene expression during the various stages of embryonic and larval development of hybrids. Bluegill, pumpkinseed, and their hybrids were collected and gametes from each extracted and used for in-vitro fertilizations to make F1 hybrids as well as the backcrosses of each species. Embryos were raised and sampled at various developmental stages. Using molecular techniques, researchers are determining when certain genes turn on during development and the patterns of inheritance of nuclear DNA markers.

Estimating fish abundance: simulating evasive behavior during netting
R. Herendeen, P. Bayley Oregon State University)
Size (and hence age) distribution of fish shows their reproductive health. Determining the distribution from net-capture data is subject to bias because of larger fishes' higher ability to evade the research net. Researchers have explicitly modeled the size-dependent evasion process during the setting-out of a purse seine. This allows researchers to convert the observed size distribution in the purse seine to the actual distribution. Model results agree qualitatively with observation; researchers continue to calibrate the model with field data (in which a larger, impenetrable block net is used to determine what fish are actually present).

Effect of light intensity and habitat complexity on predator-prey interactions in fishes
L. Einfalt, D. Wahl
Many predators visually forage for prey. Light intensity and availability of habitat are important abiotic factors influencing predator-prey interactions. In a series of laboratory experiments, researchers evaluated the effect of these factors on foraging for a fish predator (walleye) and two prey (bluegill and golden shiner). Previous studies indicate walleye forage in low light or turbid conditions. The two prey, however, are active during the day and differ in morphology and anti-predator behavior. Survey researchers found walleye were better foragers in low-light conditions due to increased activity and decreased prey vigilance. Prey, however, can compensate for decreased light and lack of habitat by switching antipredator tactics. Future research will use a comparative approach by repeating these experiments with a predator adapted to daytime foraging.

Genetic analysis of sportfish populations in the upper Midwest
R. Fields, T. Kassler, J. Ludden, M. Hudson, V. Tranquilli, M. Desjardins, D. Philipp, M. Jennings, M. Staggs (Wisconsin Department of Natural Resources), P.J. Wingate (Minnesota Department of Natural Resources), C.A. Toline (Utah State University)
The stock concept states that species of fish are composed of genetically distinct populations that are uniquely adapted to their environments. To identify individual stocks of key sport fishes, researchers are analyzing populations of 12 species of fish from distinct watersheds in the upper Midwest. Three molecular genetic techniques--protein electrophoresis, RFLP analysis of mitochondrial DNA, and RAPD DNA analysis--were used to assess the genetic variation present within and among populations of each species. The variation that was identified has been used to define biologically relevant conservation management units.

Spawning behaviors of stoneroller minnows
M. Sabaj
Two species of stoneroller minnow occur in Illinois: the central stoneroller, Campostoma anomalum, and the largescale stoneroller, C. oligolepis. The central stoneroller is widespread and often common. The largescale stoneroller is restricted to northern Illinois and a few places in central Illinois where it occurs with the central stoneroller. Although stable in the north, the largescale stoneroller has disappeared from many streams in central Illinois. Spawning behaviors and habitat requirements of the two species are being studied to determine what factors may have contributed to the decline of the largescale stoneroller in central Illinois.

Evaluation of commercial navigation and indirect effects on fish behavior in large river systems
E. Gittinger, D. Soluk, D. Wahl, J. Dettmers
Barge traffic has the potential to directly increase mortality of fishes. Alternatively, fish may exhibit avoidance behaviors and move away from barges in large river systems. If this is found to be true, then the costs associated with these behaviors should be evaluated as well as how an increase in barge traffic may impact the fishes of large rivers. This study is being conducted in Reach 26 of the Mississippi River and the lower 35 miles of the Illinois River. Hydroacoustics are being used to observe fish movements before, during, and after barge passage.

Observing fish movements using a phased array hydroacoustic unit
E. Gittinger, D. Soluk, D. Wahl, J. Dettmers
Both the River Continuum Concept and the Flood Pulse Concept suggest that fish do not reside in the main channel of large rivers, but that they utilize the main channel simply as a corridor to go from one place to another. Although recent studies have found significant populations of fishes in the main channel, this alone is not contradictory because it is not known whether the fish are transient or persistent. To address these questions, a hydroacoustic unit was used to horizontally scan large areas of the main channels in Reach 26 of the Mississippi River and the lower 35 miles of the Illinois River. In spite of high current velocities (often > 1 m/s), fishes persist in the main channel. These results indicate that main channels may be important habitat for fishes in large floodplain rivers.

Fish use of moist soil impoundments on floodplains
K. Blodgett, K. Irons, J. Stoeckel, R. Sparks
A major issue is whether fish that enter moist soil impoundments (managed for food plants that attract waterfowl) in spring flood are able to reproduce, as they once did in natural floodplain lakes and wetlands. A second issue is whether the young fish and adults are able to return to the river when the impoundment is drained during the summer growing season. In 1996 Survey scientists began an assessment of larval fish production in the moist soil management unit of Lake Chautauqua, a national wildlife refuge on the Illinois River. In 1997 researchers added a component to evaluate larval fish food habits and fish/zooplankton dynamics.

Sportfishing in Lake Michigan
W. Brofka, J. Dettmers, J. Marsden
A survey of sportfishing in the Illinois portion of Lake Michigan was conducted from March 1 to September 30, 1997. The survey covered all legal sportfishing during that period excluding fishing from chartered boats and smelt fishing. The intent of the survey was to provide reliable estimates of sportfishing activity, sport fish harvest, expenditures for sportfishing, and the quality and distribution of sportfishing. Estimated total fishing effort for pedestrians and boaters was 610,000 angler hours. Estimated total harvest included 59,100 yellow perch, 9,300 brown trout, 3,600 rainbow trout, 5,900 lake trout, 92,700 coho salmon, and 4,900 chinook salmon. Estimated expenditures for boats, motors, trailers, fishing gear, and automobile gas were $10 million. The yield value of the sportfishing harvest was approximately $1.35 million.

Potential effects of increased commercial navigation on fishes in the Mississippi and Illinois rivers
J. Dettmers, D. Soluk, D. Wahl
Towboat and barge traffic has the potential to directly increase the mortality of fishes in the main channel of the Mississippi River. To describe this potential, Survey researchers will continue to monitor the abundance and distribution of fishes in Pool 26 of the Mississippi River and the lower Illinois River, as well as estimate the proportion of fishes killed by towboats. Research results to date reveal that a diverse assemblage of larval, juvenile, and adult fishes use the main channel, with eight larval taxa and 24 species of larger fish collected during 1996. The distribution of some large fishes may be influenced by navigation locks and dams. Blue catfish and bigmouth buffalo were present only in more lakelike regions immediately upstream of the lock and dam, whereas lake sturgeon, shovelnose sturgeon, blue catfish, and shorthead redhorse were distributed only well upstream of the dam. In addition to this ongoing sampling, researchers expect to explore indirect effects of commercial navigation on fishes, river food-web interactions, and recruitment patterns of fishes.

Evaluation of indirect effects of commercial navigation on fish behavior in large river systems
E. Gittinger, D. Soluk, D. Wahl, J. Dettmers
Barge traffic has the potential to directly increase mortality of fishes. Alternatively, fish may exhibit avoidance behavior and move away from barges in large river systems. This study is being conducted in Reach 26 of the Mississippi River and the lower 35 miles of the Illinois River. Hydroacoustics are being used to observe fish movements before, during, and after barge passage. Purse seining is also being used in the presence and absence of the barges to help verify the hydroacoustical readings and to offer some insight into what fish assemblages are present in the rivers.

Creel surveys on Illinois impoundments
P. Perea, B. Carroll, J. Machung, L. Miller-Ishmael, D. Philipp, P. Bayley (Oregon State University), D. Austen, S. Sobaski (IDNR Fisheries)
Sportfishing is a significant recreational activity in Illinois, as evidenced by the sale of nearly 1.5 million licenses annually. Since 1987, INHS scientists have conducted angler surveys on 68 state-managed lakes to estimate the total fishing effort; the species, numbers, and weight of fish harvested and released; and the species targeted by anglers at these lakes annually. The data collected are directly useful to the fisheries management of these lakes, especially in evaluating the effects of short-term management changes and supplemental stocking on yield and catch per angling effort and the impact of sportfishing intensity on the resource.

Use of navigation dams to benefit plant and animal communities by naturalizing water regimes
R. Sparks, K. Blodgett, M. Demissie (Illinois State Water Survey)
Harmful water-level fluctuations in the Illinois River are more frequent and of greater magnitude than they were prior to 1900. Major reasons for these changes include 1) loss of vegetation, which resisted flow and smoothed crests, along the channel and riparian zones; 2) operation of dams for navigation; 3) loss of hydraulic storage and conveyance on the floodplain because of levees; and 4) dramatic changes in drainage from channelization, tiling, and increases in impermeable surfaces (e.g., rooftops, roads, parking lots). Changes in operations of the dams could reduce these unnatural fluctuations and aid in the recovery of native vegetation.

Food-web dynamics in sunfish communities
S. Chipps, D. Wahl
Evidence for trophic cascades provides a foundation for understanding food-web dynamics in aquatic ecosystems. "Top-down"or " middle-out" interactions help describe direct and indirect linkages among trophic levels. In these cases, predation plays an important role in structuring aquatic food webs. Among sunfish communities, phenotypic plasticity allows species to utilize different resources in the presence of congeners. However, effects of these behavioral niche shifts on food-web structure is not clear. Using sunfish communities as a model, this research is evaluating the role that behavior plays on food-web configuration in ponds and shallow lakes.

Hydroacoustics: a tool for understanding fish-habitat association in rivers
R. Claramunt, J. Dettmers, D. Wahl, D. Soluk
Large floodplain rivers, such as the Mississippi and Illinois, are composed of a variety of different habitats (e.g., backwater, side channel, main channel). The majority of sampling done to understand the importance of these different habitat types to fish occurs outside the main channel because of high-current velocities. As a result, present knowledge on fish abundances, species composition, and habitat utilization in the main channel is lacking. Through midwater and bottom trawls, Survey researchers have found that the main channel supports an abundant and diverse fish assemblage. A digital 200-kHz single-beam hydroacoustic system is being used to investigate questions such as How do fish survive in high-current velocities that are typical of the main channel? and Where are fish located in the main channel? Fish targets have been found to be strongly associated with sand dunes in the echograms from the Mississippi River. However, when dunes are not present (as in the Illinois River), fish targets are more evenly distributed, both vertically and horizontally. Sand dunes may be a critical habitat for river fishes that have adapted to the conditions in the main channel of large rivers.

Effects of abiotic and biotic factors in determining larval fish growth rates
R. Claramunt, D. Wahl
The factors and mechanisms that influence early life stages of fishes are complex and important in determining how many fish reach the adult stage. Researchers are evaluating the role of several environmental factors in determining the growth of larval fish species. Sampling was conducted in inshore and offshore habitats using push nets in 21 Illinois reservoirs. Larval sunfish (Lepomis spp.), crappie (Pomoxis spp.), gizzard shad (Dorosoma cepedianum), and minnows (Cyprinidae) were collected from May through July. Lakes were classified based on morphometric and limnological variables and compared to larval fish growth rates. Latitude, lake temperature, and characteristics of zoo-plankton populations (species and size composition) appear to be most highly correlated with growth. The relative importance of abiotic and biotic factors to growth may vary with fish species and habitat. Results of this research will help to make predictions of fish reproductive success and recruitment across systems.

BASS

Largemouth bass recruitment in Illinois
S. Chipps, J. Hoxmeier, D. Wahl, D. Philipp
Largemouth bass recruitment depends on a variety of biotic (e.g., prey availability, predator abundance, population structure, vegetation, etc.) and/or physical factors (e.g., spring water levels and temperature, spawning habitat, human disturbance such as angling). As a result, the need to identify which of these factors consistently influence year-class strength for largemouth bass in Illinois is an important component of successful management of the species. Researchers are examining largemouth bass recruitment dynamics across a gradient of lakes in Illinois. Determining factors that affect largemouth bass recruitment will aid in predicting year-class strength-developing management programs, and promoting efficient use of the supplemental stocking program.

Evaluation of largemouth bass stocking program
J. Hoxmeier, S. Chipps, D. Wahl, D. Philipp
Although largemouth bass are stocked extensively in Illinois, little is known about the long-term contribution of hatchery fish to the natural population. Factors that influence stocking success include prey availability and predation, or abiotic factors, such as water temperature and water level. Prey availability and predation are dependent on the size of stocked largemouth bass. As a result, the current study is examining lakes and reservoirs throughout Illinois to determine factors affecting growth and survival of stocked largemouth bass. Evaluations are being made of small and large fingerling bass to determine appropriate stocking size. In addition, researchers are evaluating the contribution of stocked fish to future reproductive success and harvest. These results will be used to develop management strategies that optimize use of these important stocked sport fish.

Catch-and-release angling in bass
D. Philipp, F. Phelan (Queen's University Biological Station), M. Kubacki (Arizona Game and Fish), C.A. Toline (Utah State University), D.B.F. Philipp (Deutsche Morgan Grenfell)
Because both largemouth and smallmouth bass are highly prized sport
fish, many are captured in the spring when males are still on nests providing parental care for their young. Little is known, however, about the effects that practice has on the reproductive success of nesting bass. Data collected from experimentally captured-and-released bass (e.g., male size, brood developmental stage, egg score, return time, and predation rates) are being used to determine how catch-and-release angling impacts the reproductive success of both species and how those impacts can be minimized.

Local adaptation in largemouth bass
D. Philipp, J. Claussen
Through natural selection and random drift, populations diverge and become genetically tailored for the environments they inhabit. When foreign genes are introduced into a native population, and interbreeding occurs among individuals, the genetic makeup of that population is disrupted, a change that often has negative effects. To assess these potential negative impacts, a series of experiments has been conducted to compare survival, growth, and reproductive success of genetically defined stocks of largemouth bass in different geographic habitats. In all experiments survival, growth, and reproductive success of the local stocks were superior to those of the introduced stocks. In addition, extensive introgression among stocks occurred within a very few generations and the performance and fitness of introgressed individuals was poorer than that observed for individuals in the pure local stock.

Vulnerability of largemouth bass to angling
D. Philipp, J. Claussen, D. Burkett (U.S. Fish and Wildlife Service),
J. Koppelman (Missouri Department of Conservation), C.A. Toline (Utah State University)
Little is known about the long-term effects of angling harvest on sport fish populations. Research has demonstrated that individual largemouth bass are not equally vulnerable to anglers' efforts. In an experimental population exposed only to catch-and-release fishing, certain bass were never caught, whereas others were captured several times. A selective breeding experiment has further demonstrated that hook-and-line vulnerability is heritable. Researchers are now studying the long-term impacts that heavy angler harvest can have on native largemouth bass populations.

Largemouth and smallmouth bass reproductive success
D. Philipp, J. Claussen, T. Kassler, F. Phelan (Queen's University Biological Station), M. Kubacki (Arizona Game and Fish)
For reproduction, male largemouth and smallmouth bass build nests in lake or stream substrates, court and spawn with females, and then remain to protect their brood, providing parental care for up to four to six weeks after fertilization of the eggs. To determine how reproductive success varies among years, researchers have been intensively monitoring the spawning success as well as the duration of nesting and parental care behavior in both species for the past seven years. Four distinct habitats in southern Ontario are being compared to some in Illinois to determine the spatial and temporal differences among populations.

Spawning dynamics of largemouth and smallmouth bass populations
D. Philipp, T. Kassler, F. Phelan (Queen's University Biological Station), C.A. Toline (Utah State University)
The annual spawning histories (location, date, mating success, and reproductive success) of all male smallmouth bass in a 1.5-km section of a stream in southern Ontario and in a 3-km section of a stream in Illinois and of all male largemouth bass in an 87-acre lake in southern Ontario are being monitored. From individual mark and recapture data, preliminary results indicate that in subsequent years successful males return to previous spawning sites (within 3-4 m), whereas unsuccessful males may move up to 0.5 km. Determining the factors that affect individual variation in male reproductive success will help develop better management programs for these species.

Temperature-based optimum foraging of largemouth bass
C. Smith, R. Fischer, D. Wahl
Growth of largemouth bass is highly dependent on the abiotic and biotic factors of temperature and prey abundance. Gizzard shad may segregate themselves from largemouth bass by inhabiting areas outside of the optimum temperature for bass. In doing so, maximum bass growth rates may not be achieved due to the bass foraging at these less-than-ideal temperatures. This study will examine gizzard shad densities and locations through the use of hydroacoustics as well as largemouth bass movements in relation to gizzard shad using radiotelemetry. These results will determine if largemouth bass can reside for significant periods in zones of suboptimal temperatures where the prey forage base is located.

BLUEGILL

Spawning dynamics of bluegill
J. Claussen, D. Philipp
Bluegill have highly social reproductive behaviors in which some males build nests in colonies, court and spawn with females, and provide all parental care for the young in the nest. This long-term study has monitored the annual variation in the number of males that build nests, spawn, and successfully raise a brood off the nest in a 2-km study area of Lake Opinicon, Ontario. Yearly comparisons will determine how environmental changes, such as temperature, affect the variation in the number of breeding males and females in the population as well as how changes in the overall breeding population affect clutch size. These data are providing information needed for modeling bluegill population dynamics in the Midwest that will aid in the production of successful management programs for this important species.

Factors affecting bluegill population size structure
J. Hoxmeier, J. Claussen, D. Aday, D. Philipp, D. Wahl
Factors that control bluegill population size structure include growth rate, life span, and age at maturation. Stunted bluegill populations can result from overharvest, density-dependent growth imitation, large portions of the population maturing at early ages, or from an overabundance of cuckolders. Researchers are 1) categorizing Illinois bluegill populations based on adult size structure using existing creel surveys and standardized sampling, 2) examining life history characteristics in selected impoundments, and 3) determining which factors are controlling size structures in each of these populations. The goal is to develop an adaptive management experiment that will assess the ability of several management alternatives (regulations, predator manipulations) in altering bluegill size structure.

Angler attitudes toward harvest regulations for bluegill
T. Edison, D. Austen, D. Wahl, D. Philipp
An important tool in fisheries management is angler surveys, which provide information on attitudes toward proposed regulation changes. Regulations might be useful to improve size structure of bluegill populations and improve fisheries. Currently, few harvest restrictions exist on bluegill populations throughout Illinois. Through the use of an angler attitude survey researchers will categorize fishermen's attitudes about lakes that contain stunted bluegill populations and those lakes that contain quality bluegill populations. Some potential regulations that anglers will be asked about are size limits, creel limits, closed seasons, and closed portions of a lake.

Reproductive strategies in bluegill
D. Wahl, D. Philipp, J. Claussen, J. Hoxmeier
Male bluegill exhibit two mutually exclusive alternative reproductive strategies. The first is the "parental" strategy, where males delay maturation, build nests in colonies, court and spawn with females, and show parental care. The second is "cuckoldry," where males mature at a much younger age and smaller size and "steal" fertilizations from spawning parental males by sneaking into their nests or by mimicking females. In addition, age at maturation of parental males appears to be highly phenotypically plastic. How these life history characters as well as density-dependent growth rates influence population size structure is being evaluated in an effort to better manage bluegill.

Differences in macroinvertebrate communities between gizzard shad and bluegill dominated systems: effects on growth rates of young-of-the-year largemouth bass
J. Kline, D. Wahl
Gizzard shad (Dorosoma cepedianum) have been shown to have a major effect on trophic interactions in reservoirs and may influence macroinvertebrate populations. The resulting macroinvertebrate community may, in turn, affect growth rates of young-of-the-year largemouth bass (Micropterus salmoides) prior to the switch to piscivory. Researchers are evaluating the role of macroinvertebrates in influencing the growth of largemouth bass by sampling in six Illinois reservoirs, three of which are gizzard shad dominated and three are bluegill (Lepomis macrochirus) dominated. Research results will help clarify the role of macroinvertebrate and fish community interactions in influencing the growth of young-of-the-year largemouth bass.

WALLEYE

Individual-based model for walleye
T. Galarowicz, D. Wahl, R. Herendeen
Fish growth and population dynamics are influenced by size-dependent mechanisms and physical factors. Individual-based models, which follow individuals of a species rather than an "average" individual, provide additional insight into these relationships. By modeling foraging, daily growth, and mortality using an individual-based approach we hope to predict growth and survival of young-of-the-year walleye. Parameters for the model are based on extensive field data and ongoing laboratory foraging experiments.

Evaluation of walleye stocking program
J. Hoxmeier, D. Wahl
Success of walleye stocking is highly variable, and reasons for successes are not well understood. Factors influencing stocking success may include prey availability, predation, or abiotic factors such as water temperature. Prey availability and predation are highly dependent on the size of the walleye. The current study is examining 11 lakes across Illinois to understand factors causing differences in growth and survival among stocked walleye fry as well as small and large fingerlings. These results will be used to develop management strategies that optimize stocking of these important sport fish.

Aquaculture of walleye
T. Galarowicz, D. Wahl
Walleye are popular as food and sport fish throughout the country, but commercial harvesting is not allowed in the United States. As a result, there is an increased interest in culturing walleye to market size to meet this demand. In response, the North Central Regional Aquaculture Center funded a multi-research group that includes the Illinois Natural History Survey to focus on developing techniques for commercial culture of walleye by evaluating growth, feed efficiency, and stress response under various culture conditions. Researchers from INHS will use a bioenergetics model to study different components affecting culture success.

YELLOW PERCH

Yellow perch early life history
S. Robillard, J. Dettmers, J. Marsden
Larval yellow perch are being sampled to assess their abundance and diel distribution. Zooplankton are also being sampled to determine whether the available food supply for larval fish has dramatically changed over the past decade. Young-of-the-year (YOY) yellow perch collections were made with a bottom trawl to assess survival of larvae to the YOY stage. Relatively low catches of larval and YOY perch indicated that a strong year-class was not produced in 1997, which will mark nine consecutive years of poor recruitment. The effect of alewife predation on yellow perch larvae was assessed. Researchers also developed a method to monitor yearly abundances of perch egg masses and sampled ichthyoplankton with light traps and Miller samplers.

Yellow perch population assessment
S. Robillard, J. Dettmers, J. Marsden
Adult yellow perch were marked with Floy tags and then recaptured at sites with either cobble, sand, or mixed cobble and sand substrates near the IDNR Lake Bluff index station. Over 4.6% of the tagged fish were recaptured at liberty in the first six months. Greater numbers of perch were captured at cobble sites. During spawning, 55% of the tagged fish were recaptured at the same site as they were tagged, suggesting relatively strong spawning-site fidelity. The mean age of adult perch has continued to increase due to reduced recruitment of younger fish to the adult population.

Geographic Information System, Mapping, and Analysis

The Survey's Geographic Information System (GIS) is a computer-based system used to map, analyze, and better understand the diverse landscapes that exist in Illinois. GIS systems use geographic location--mapping where things are--as the basis for the organization, synthesis, and analysis of information. The Survey's GIS includes information on statewide land cover, species ranges, collection site locations, wetlands, public lands, administrative boundaries, census tracts, roads, streams, and many other geographically referenced datasets and digital base maps. The Natural History Survey has collaborated with the State Geological Survey, State Water Survey, Waste Management and Research Center, and the Illinois Department of Natural Resources' Office of Mines and Minerals and Office of Realty and Environmental Planning to share data and minimize duplication of effort.
To support its Geographic Information System the INHS currently uses Arc/Info version 7.2.1 and ArcView version 3.0 from Environmental Systems Research Institute (ESRI), Redlands, CA, PCI Image Processing software from PCI, Ontario, Canada, Fragstats spatial pattern analysis program in addition to other word processing, drawing, presentation, and statistical software. These programs run on a series of networked Sun workstations (Solaris 2.5 operating system), Macintosh (MacOS 8.1), and Dell (Windows NT version 4.0) computers. Other resources include over 150 Gb of disk space, 8 Trimble Global Positioning System (GPS) units, a pair of Leica Vector Field binoculars, film recorders, scanners, and printers. INHS benefits from its close association with other surveys and DNR divisions involved in the use and application of GIS technology to natural resources issues. These benefits include shared data development and shared resources, such as large format inkjet plotters and a CD-writer.
Mapping natural and cultural resources with GIS helps researchers and managers integrate specific locations and field observations into broader landscapes. This makes it possible to compare and characterize different areas of the state and conduct research at the regional level. For example, watersheds can be compared on the basis of how much forested or agricultural land they contain. The Survey's GIS provides a common framework for integration, collaboration, and decision making. It also takes advantage of the visual language of maps to portray and reveal relationships in an easily understood way.
The GIS professionals within the Survey have a 15-year history of research, database development, and support to the Survey and the state. Recent accomplishments include creation and publication of the land cover database of Illinois, publication of the Resource Rich Area report, creation of the Illinois Wetlands Inventory in digital form, creation of a digital spatial database of many public and ecologically significant lands, and participation with the other Illinois scientific surveys in the creation of a National Spatial Data Infrastructure (NSDI) node on the Internet. Much of the GIS data generated by the Survey has been published on CD-ROM. These digital spatial databases for Illinois are widely used throughout the state by schools, planning agencies, consultants, and local governments. Illinois was the first state in the nation to publish GIS data in this way. The GIS staff are also leading efforts to integrate global positioning technology (GPS) into field work and research efforts at the Survey. Hand-held GPS receivers rely on a network of satellites to resolve locations on the ground to within a few meters. This level of positional accuracy exceeds what is possible using more traditional paper maps.
The availability of databases covering the entire 56,000 square miles of Illinois, in relatively high detail, combined with advances in computer technology provide researchers the ability to analyze landscapes in ways not previously possible. The utility of GIS is growing as managers and researchers seek to better understand relationships and interactions not just at specific locations but across broader geographic areas such as watersheds. GIS has been integral to the Critical Trends Assessment Project (CTAP), EcoWatch, and the Ecosystem Partnership programs of DNR by providing data, analysis, and maps for assessment and monitoring of the state's ecological resources. During the past year this has included the production of over 1,000 site-specific maps for use by EcoWatch volunteers throughout Illinois. Each of Illinois' EcoSystem Partnerships was provided a regional map of land cover and existing recreational lands as a basis for planning and discussion.
Numerous other Survey projects and research efforts rely upon GIS and its unique capabilities. These include management of the federal Gap Analysis Program in Illinois, which seeks to map biodiversity; linking of collection locations to their associated database to help scientists consider collection history and spatial relationships among the collection sites; identification of large grassland tracts in Illinois to assist managers in targeting limited resources intended to improve the ecological functioning of grasslands; use of remote sensing and GIS data to better understand and predict the distribution of ticks and lyme disease transmission in Illinois and the upper Midwest; analysis and characterization of wild turkey habitat and populations in Illinois based on sightings filed at check stations by bow hunters; research relating trends in avian populations to changes in habitat; delineation of wetlands and updates of the Illinois Wetland Inventory using GPS for Illinois Department of Transportation projects; and modeling the spread of western corn root worm populations. Additionally, GIS research projects at the Survey include epidemiological research on the potential for transmission of canine distemper by raccoons and deer in Cook County; a study of habitat use by raccoons; mapping specific collection locations of amphibians and reptiles throughout the state; monitoring the movement and mortality of fox and coyote using radiotelemetry, GIS, and GPS; and image analysis and GPS support for the De Pue Wildlife Management Area site characterization project.
The Survey will continue to rely upon GIS technology to conduct and support research and inform the public about the natural resources of Illinois. GIS is a powerful tool that helps us visualize and better understand and represent the landscapes of Illinois and the living things that inhabit them.

geospatial Analysis and Landscape Studt Projects

The Survey's Geographic Information System (GIS) has been invaluable in helping Survey scientists and staff to map, record, and analyze the diverse natural landscapes that extend over Illinois. GIS and related technologies, such as Global Positioning Systems (GPS), provide researchers with powerful tools for the study and analysis of issues relevant to Illinois. In particular these tools help researchers better understand landscapes and discover relationships that previously were difficult or impossible to quantify. Maps generated using the GIS communicate information in an easily understood visual language. These technologies also provide a common framework for collaboration and promote interdisciplinary approaches to research and problem solving.

Landscape analysis for long-term ecological monitoring
M. Joselyn, L. Suloway, E. Brewer
The long-term ecological monitoring programs being conducted by CTAP biologists and EcoWatch volunteers required identification, statewide, of locations suitable for field sampling. GIS analysis was used to identify potential monitoring sites for four habitat types--forest, stream, grassland, and wetland--based on criteria specific to each habitat. Over 1,000 maps depicting relevant habitats and potentially suitable sampling locations were produced this year for use in the field by scientists and volunteers.

Ecosystem partnerships
L. Suloway, M. Joselyn
Ecosystem Partnerships are comprised of public and private constituencies designed to provide natural resource stewardship on a local basis. Using GIS technology, each of 22 partnerships was provided with a large-format land cover map of its partnership. The maps provided valuable information for purposes of discussion, planning, management, and public display. GIS analysis and mapping also provided information about land cover, wetlands, watersheds, natural divisions, and publicly owned areas of ecological significance to the partnerships.

Trends in avian populations
L. Suloway
Trends in bird populations provide a valuable indication of environmental health and change. Extensive monitoring of the bird populations in Illinois has taken place over the past 30 years as part of the Breeding Bird Survey (BBS) program. Analysis of these data to determine changes over time for individual species, guilds, and the overall avian population began this year. The integration of the BBS data with other GIS layers (e.g., land cover, watersheds, natural divisions) will allow statewide, regional, and local analyses and help characterize the status of species and habitats in Illinois.

Gap analysis in Illinois
L. McKinney, J. Aycrigg, M. Joselyn, P. Brown
The federal Gap Analysis Program, administered through the Biological Resources Division of the U.S. Geological Survey, seeks to create nationwide, georeferenced databases of vegetation communities, vertebrate distributions, and stewardship of public lands. These data will provide an overview of the distribution and conservation status of selected components of biodiversity. In Illinois these databases are being developed to be of maximum benefit to issues and concerns of our state. In particular the spatial accuracy and resolution of the Illinois databases exceed those required by the national program. The use of GIS makes it relatively easy to aggregate these data, once developed, to meet the national standards. Specific accomplishments in each of these areas are detailed under individual headings in this report.

Mapping vegetation communities
L. McKinney, M. Joselyn, P. Brown
Mapping vegetation communities (oak-hickory, cypress-tupelo, etc.) provides a foundation for species/habitat modeling and is central to the Illinois Gap Analysis Project (GAP). This federal program seeks to map the components of natural systems that make up diversity in the nation. The forests of southern Illinois were classified into 30 forest communities by using satellite imagery, elevation data, and the land cover database of Illinois.

Mapping the distribution of amphibians and reptiles
J. Aycrigg, L. McKinney, C. Phillips, T. Maples
Species richness, the number of different species occurring in a particular area, is a central part of the Illinois GAP program. Mapping species richness will be used to identify species and assemblages that are not protected in the current network of public lands. Known locations of amphibians and reptiles were accurately mapped and subsequently used to determine the total number of amphibian and reptile species occurring in areas covering 635 square kilometers throughout Illinois. The intent is to provide information to support proactive, rather than reactive, management at both the local and regional level.

Public lands of Illinois
L. McKinney, J. Aycrigg, D. Greer, K. Hunter
The public lands of Illinois include state natural areas, state nature preserves, state parks, state fish and wildlife areas, state forests, national forests, and county forest preserves. The boundaries of these areas have been mapped and classified by management status relative to preserving biodiversity. Knowing the existing distribution of lands that are managed to preserve biodiversity is a central aspect of the Illinois GAP program. Presently in Illinois such areas occupy well under 1% of the state, comprised primarily of nature preserves.

Large grasslands in Illinois
L. McKinney, M. Joselyn, J. Aycrigg, J. Herkert
Native prairies in Illinois have been nearly extirpated and are now reduced to fragmented islands in a landscape dominated by managed agricultural lands. Non-native grasslands, which are affected by agricultural practices, have replaced native prairies in many portions of the state and now constitute the habitats inhabited by prairie fauna. This project set out to identify existing grasslands in Illinois and to examine their spatial pattern in a broader landscape. Field work will validate the landscape-level management potential of areas with relatively high concentrations of grasslands, and their importance as habitat for grassland species.

Illinois natural resources geospatial data clearinghouse
M. Joselyn
The Natural History Survey participated with the State Geological Survey, State Water Survey, Waste Management and Research Center, Office of Mines and Minerals, and Office of Realty and Environmental Planning in the creation of the Illinois Natural Resources Geospatial Data Clearinghouse. This clearinghouse makes geospatial data accessible via the Internet to citizens of Illinois and the world as part of efforts by the Federal Geographic Data Committee (FGDC) to create a national spatial data infrastructure. Using a standard web browser, individuals can enter key words or identify geographic areas and retrieve listings of the relevant geographic datasets that can subsequently be downloaded.

Digitizing collection locations
T. Kompare, C. Mayer
Collection localities from the Survey's scientific collections are being digitized into the Survey's Geographic Information System (GIS). As the INHS fish, mussel, and crustacean collections continue to grow, the locality information is entered and stored in the GIS. This layer of data creates a link to other data already available through the GIS, allowing scientists to analyze these data in ways not before possible.

Modeling Wild Turkey habitat in the Illinois landscape
T. Van Deelen, P. Brown, M. Joselyn, D. Greer, T. Maples, J. Garver (IDNR)
For many years, the IDNR has asked deer hunters to indicate on county maps where they saw turkeys during their deer-hunting activity. These maps represent a unique statewide record of turkey use of the various habitats available in Illinois. Researchers are digitizing the turkey sightings and standardizing observations for differing levels of deer hunter effort in the different counties. This database will then be used to model turkey habitat relative to land cover characteristics and landscape features in the natural divisions of Illinois. This model will help IDNR managers evaluate turkey management and restoration efforts and will help researchers understand turkey ecology in the agricultural Midwest.

Environmental determinants of Lyme disease foci
U. Kitron, C. Jones, D. Greer
The environmental factors that contribute to geographic variation in the prevalence of Lyme disease-carrying ticks are not well understood. This project is using remote sensing data and GIS to better understand and predict the distribution of ticks and Lyme disease transmission in Illinois and the upper Midwest.

Spatial epidemiological modeling
T. Kompare; M. Lancaster, B. Deal, K. Spanski, C. Farello, R. Lambert, B. Hannon (University of Illinois)
Rabies is a disease spread across the landscape by several animal species. The construction of a model that simulates the spread of this disease was undertaken with the help of the INHS Geographic Information System. Researchers are modeling a theoretical outbreak of rabies in Illinois. If such an outbreak were to occur, this model could be utilized to evaluate different methods of control.

Global positioning
L. McKinney
Global positioning technology allows field biologists to map sites and boundaries in real time while in the field. Increasingly, this technology is being used by various programs and researchers to incorporate field data directly into the Survey's GIS. This approach to data gathering is more accurate and more efficient than methods that have historically been used to integrate field data into the Survey's GIS.

Land cover and stream quality
T. Kompare
Several past studies report that stream quality, as measured by biotic content, is affected by its watershed's land cover characteristics. With the use of the Survey's Geographic Information System, an investigation is under way to define this relationship further. This investigation will cover watersheds of various sizes throughout the state. The goal of this project is to identify key land cover characteristics that most influence biotic characteristics of our streams.

Wetlands

Wetlands are an extremely important component of our natural landscape. Wetlands reduce the deleterious effects of floods and drought by storing and gradually releasing water. Wetlands reduce erosion and remove sediment from runoff, and also filter or remove toxicants, such as heavy metals and excess nutrients. Some wetlands are areas of groundwater recharge. As places to observe and photograph nature, hike, hunt, or fish, wetlands have recreational and aesthetic values.
Wetlands provide important habitat for native plants, fish, game, and other wildlife, and are therefore crucial in maintaining our biodiversity. In Illinois, 90% of amphibian species, 78% of reptiles, 33% of plants, 14% of mammals, and 9% of birds are dependent on wetlands. Of the 500 species of animals and plants listed as threatened or endangered in Illinois, 232 species utilize wetlands to some degree.
Throughout the United States, wetlands have been disappearing at an alarming rate. Despite federal and state legislation designed to protect wetlands and mitigate for their loss, these areas continue to decline. Originally, wetlands made up 23% of the Illinois land area (8.2 million acres). Currently, only 2.6% of Illinois (0.9 million acres) remains in wetlands. The primary causes of this loss are conversion of land for agricultural purposes and industrial and residential development to support population growth. Aside from outright loss, existing wetlands are subjected to various forms of degradation, which greatly reduce their ability to provide habitat for plants and animals. The most important causes of wetland degradation are alteration of hydrologic regime, increased sedimentation and pollution of incoming water, and invasion by exotic species.
Scientists at the Illinois Natural History Survey are dedicated to increasing scientific knowledge and public awareness of wetlands, and helping to reduce the loss or degradation of this valuable resource for the state of Illinois. Two groups at the Survey work directly with the Illinois Department of Transportation (IDOT) on wetlands throughout the state. The Further Studies Group from the INHS Center for Biodiversity monitors all types of land, including wetlands, to determine high-quality areas and to locate state threatened and endangered species. The second group, the Wetland Group of the INHS Center for Wildlife Ecology, focuses exclusively on wetlands to determine acreage and quality of wetlands that may be affected by IDOT projects in order to facilitate wetland avoidance or mitigation. The Wetland Group is also involved in the assessment, design, and monitoring of sites used for wetland creation or restoration to mitigate for losses caused by IDOT projects. Group members and other staff at the Survey participate in numerous environmental education activities for schoolchildren and adults to increase awareness of the importance of wetlands and gain public support for their protection. A number of Illinois Natural History Survey scientists are engaged in a variety of research projects involving wetlands. These projects are designed to address causes of wetland degradation and wildlife population declines; learn more about wetland restoration and creation; understand habitat requirements and population ecology of threatened or endangered species, nongame wildlife, and game species; and to increase basic scientific knowledge of wetlands. Some of the projects involving wetlands are discussed in other sections of the annual report (e.g., exotic species, fish and wildlife management).
Wetlands are subject to degradation from several factors, which affects their vitality and value to biodiversity. One study is under way that examines the effectiveness of several species of insects being used for biological control of the exotic plant purple loosestrife (Lythrum salicaria), which is displacing native wetland species throughout the state. A second study looks at the negative effect of deer browse on the regeneration of floodplain forest trees and the species composition of forest understory. Another study looks at differences in floodplain forest understory dynamics and tree regeneration between rivers with different hydrologic regimes and between disturbed and undisturbed sections of rivers. These studies will have important implications for the management of wetlands.
Understanding key factors underlying wetland creation and the biology of plants and animals utilizing created wetlands is a critical and ongoing effort. Studies have been undertaken to describe geographic variation in plant community development in recently created wetlands and to look at plant community development in a created wetland that has been subjected to prescribed fire. Other scientists are studying amphibian colonization dynamics in created wetlands.
Use of wetlands by nesting and migratory birds is a major research effort by several Survey scientists. Studies are under way to examine reproductive success and habitat preferences of the Yellow-headed Blackbird (Xanthocephalus xanthocephalus), a species dependent on large marshes and listed as endangered in Illinois. Another study examines Prothonotary Warbler (Protonotaria citrea) population ecology in swamp forests. Other scientists are examining the effects of nest predation and cowbird parasitism on songbird breeding success in floodplain forests. Scientists involved in waterfowl research are inventorying populations, examining breeding behavior and success, and looking at the effects of ingesting heavy metals and lead shot. These studies will yield findings that may help guide management objectives and the design of preserves.
Floodplain forests require disturbances in order to reproduce, but seldom has there been an opportunity to study this phenomenon. A research project is under way that will examine tree regeneration and understory population dynamics in floodplain forests killed by the great 1993 flood.
Wetlands are critical to flood control, water pollution and sedimentation abatement, and the long-term maintenance of the biodiversity of Illinois. Survey scientists will continue to engage in a wealth of studies addressing the basic biology of wetland species and the processes linking those species.

Wetland and preliminary studies group
Plocher, Admiraal, Feist, Harper, Keene, Ketzner, Tessene, Wilm
The wetland group conducts biological surveys and wetland determinations for areas to be impacted by Illinois Department of Transportation (IDOT) projects. In the relatively new field of wetland creation, the group assesses the suitability of potential sites, monitors the development of created wetlands, and has completed the Illinois Wetland Restoration and Creation Guide. Group members are conducting research on understory dynamics in flood-killed forests, the relationships of wetland plant species abundance to hydrologic regime, comparison of plant community development following wetland creation in different natural divisions in Illinois, wetland and savanna restoration at the Middle Fork Forest Preserve, and the effect of prescribed fire on prairie-dependent insect populations. The group also conducts wetland training workshops for the Illinois Department of Natural Resources (IDNR) and the U.S. Army Corps of Engineers, and gives presentations on ecology for school children.

Plant community development in created wetlands
A. Plocher
In the relatively new field of wetland creation, little is known about how plant communities change over time. In this study, changes in community structure and species composition will be examined in eight newly created wetlands of similar design located in northern and southern Illinois. Researchers will attempt to determine whether observed differences can be attributed to geographic location or hydrologic conditions.

NOTE: Please see in Restoration Ecology section:

Tree species preferences of forest birds in the Cache River wetlands
A. Gabbe

Kaskaskia forest study
J. Taft, S. Robinson, C. Phillips, R. Sparks

* Please see in Long-term Monitoring section:

Bioresponse monitoring at the Peoria Lake Habitat Rehabilitation and Enhancement Project (HREP)
T. O'Hara, K. Irons, T. Cook, K. Blodgett

* Please see in Watershed Management section:

Effect of hydrologic alteration on floodplain forest understory dynamics and species composition
A. Plocher

* Please see in Integrated Pest Management section:

Biological control of purple loosestrife
R. Wiedenmann, D. Voegtlin, S. Post, A. Wegeng

* Please see in Endangered, Threatened, and Rare Species section:

Population dynamics of the endangered Yellow-headed Blackbird in northeastern Illinois
M. Ward, D. Enstrom

* Please see in Fish and Widlife Ecology section:

Mating behavior of Redwinged Blackbirds
D. Enstrom, K. Yasukawa (Beloit College, WI)