Plain-Bellied Watersnake

Image of a yellow-bellied watersnake
Scientific Name
Nerodia erythrogaster
Colubridae (nonvenomous snakes) in the order Squamata (lizards and snakes)

The plain-bellied watersnake is a medium-sized, heavy-bodied, dark-colored, semiaquatic snake with a plain yellow belly. It is mainly gray, greenish gray, or brownish black, with little or no pattern on its back. Populations in western Missouri are more likely to have blotches along the back and sides. The belly is plain yellow or occasionally with some orange.

This nonvenomous snake will bite viciously and smear a foul-smelling musk if captured.

Similar species:

  • Missouri has four other species of watersnakes (Nerodia spp.). The coloration, particularly the plain, unmarked belly, helps distinguish the plain-bellied watersnake from the others.
  • Watersnakes are often confused with the venomous northern cottonmouth (Agkistrodon piscivorus) and killed because of unwarranted fear. Cottonmouths are more heavy-bodied, with a larger, chunky head and a facial pit between the nostril and eye; they are darker and have a light line from the eye to the corner of the mouth.
Other Common Names
Yellow-Bellied Watersnake (former subspecies)
Blotched Watersnake (former subspecies)

Adult length: 30 to 48 inches; occasionally to 64 inches.

Where To Find
Plain-Bellied Watersnake Distribution Map

Occurs in the Bootheel and north along the Mississippi River floodplain, and along our southernmost counties and northward in western Missouri to about Buchanan, Livingston, and Linn counties.

This species is active from late March through October. Most individuals emerge from their overwintering retreats in April and early May.

Plain-bellied watersnakes prefer the quiet waters of swamps, sloughs, oxbows, slow-moving rivers and streams, floodplains, seasonally flooded bottomland woods, drainage ditches, lakes, and ponds. In summer, however, it is not unusual to find them on dry land, because they may move far away from water.

Individuals bask on logs in shallow water, on branches above the water, or along the shore.

In winter, these snakes retreat to mammal burrows, rock piles and crevices, riprap rocks along levees, and rotting stumps and logs. In north-central Missouri, this is one of the snake species that commonly overwinters in crayfish burrows.

Foods include fish, toads, frogs, tadpoles, salamanders, and crayfish. Although most other watersnake species eat mostly fish, this species seems to eat a larger percentage of frogs and toads.

Taxonomy: The plain-bellied watersnake used to be divided into several different subspecies, including the yellow-bellied watersnake (N. e. erythrogaster), occurring in eastern Missouri along the Mississippi River and in the Bootheel, and the blotched watersnake (N. e. transversa), occurring in western and southwestern Missouri, but those subspecies are no longer recognized.

Life Cycle

Courtship and mating occur in spring, especially in April and May. Females give birth to live young during August and early September, with usually 10–20 in a litter. Larger females bear larger litters. Individuals become sexually mature by about age three. Lifespan can be nearly 15 years.

As with most of our watersnakes, although it is nonvenomous, it is pugnacious. When cornered, an individual will strike or bite viciously. When captured, watersnakes also excrete a foul-smelling musk from glands in the base of the tail that it is often mixed with feces and smeared on the captor.

Snakes stir our imaginations and figure prominently in our myths, religions, and stories. We humans have invented many unfair and incorrect myths that make them seem the embodiment of evil. Curiosity and knowledge helps us overcome our prejudices.

As predators, watersnakes control populations of the animals they consume. But snakes are preyed upon themselves. Their defenseless newborns are eaten by animals ranging from large frogs and fish to other snakes and birds and mammals. Adults are eaten by predatory mammals and birds. Watersnakes' defensive behaviors (biting and smearing bad-smelling stuff on enemies) remind us that they are a prey species themselves.

Media Gallery
Similar Species

Where to See Species

Settle's Ford Conservation Area is located on both sides of the South Grand River in southeast Cass and northeast Bates Counties and is easily accessed from Cass County Route B. This 7,364-acre area
About Reptiles and Amphibians in Missouri
Missouri’s herptiles comprise 43 amphibians and 75 reptiles. Amphibians, including salamanders, toads, and frogs, are vertebrate animals that spend at least part of their life cycle in water. They usually have moist skin, lack scales or claws, and are ectothermal (cold-blooded), so they do not produce their own body heat the way birds and mammals do. Reptiles, including turtles, lizards, and snakes, are also vertebrates, and most are ectothermal, but unlike amphibians, reptiles have dry skin with scales, the ones with legs have claws, and they do not have to live part of their lives in water.