Squamata suborder Serpentes
Nerodia erythrogaster -- Plain-bellied Watersnake
All information found on this site falls under the INHS's Internet License Agreement.
Purple shade indicates vouchered specimens. Light blue (cyan)
shade indicates photographic records. Yellow shade indicates verified
sighting. Slanted hatch indicates pre-1980 records only
NOTE: Not all specimens upon which these maps are based have been verified.
Key Characteristics: Yellow or orange unpatterned belly; back scales strongly keeled; anal plate divided; back of newborn marked with black blotches, but darken within a year.
Similar Species: Eastern Racer, rat snake, cottonmouth. Juvenile resembles blotched young of many other snakes.
Subspecies: Yellowbelly water snake, N. e. flavigaster; copperbelly water snake, N. e. neglecta.
Description: Large (up to 140 cm TL), stout snake. Adult is uniformly dark brown or black, juvenile has 30 - 35 dark blotches. Belly usually yellow with no dark markings in N. e. flavigaster, usually bright orange with encroachment of dark side pigment onto belly scales in N. e. neglecta (more encroachment in larger individuals).
Habitat: Backwater sloughs, cypress-tupelo swamps, and lowland lakes and ponds with abundant vegetation and muddy bottoms. Often seen in nearby forest.
Natural History: Often leaves water to forage for amphibians. Mates in May and June and gives birth to 10-20 young in late July or August. Newborn are 20-28 cm TL. Diet includes fish and amphibians. Predators include other snakes, large shore birds, mink, and raccoons. Often killed by people who mistake it for cottonmouth.
Status: Through a conservation agreement with the U.S. Fish and Wildlife Service, the copperbelly subspecies is protected as though it were listed in Illinois. Threats include drainage of wetlands, removal of aquatic vegetation, and loss of border habitat suitable for amphibians.