The northern watersnake and midland watersnake are Missouri's two subspecies of common watersnake (Nerodia sipedon). Together they occur statewide. The color is variable: gray, tan, or reddish brown with dark crossbands or blotches. The belly is cream-colored or yellow, with orange, red, brown, or black spots or half-moon markings. These two subspecies are the most commonly encountered watersnakes in Missouri.
- The northern watersnake (Nerodia sipedon sipedon) occurs in nearly all of Missouri except for several southern and southeastern counties (it is apparently not present south of a line roughly between Christian and Stone counties to Cape Girardeau County).
- The midland watersnake (Nerodia sipedon pleuralis) occurs in the southeastern third of Missouri, south of a line drawn from the southwest corner to St. Louis. It's common in clear, Ozark streams.
Thus there is a broad zone of overlap of the two subspecies in a southwest-to-northeast band running from the southwest corner to St. Louis, and from Stone County to Cape Girardeau County. In this zone, the two subspecies interbreed and may show coloration patterns in between the two subspecies.
Watersnakes are medium-sized semiaquatic snakes with keeled scales along the back, making them feel rough to the touch. They are nonvenomous, but they will bite viciously and smear a foul-smelling musk if captured.
- The northern watersnake subspecies (N. s. sipedon) is gray or brown, with numerous dark brown bands along the front third of the body. The bands turn into alternating blotches in the latter part of the body. The crossbands are reddish brown, dark brown, or nearly black. The belly is cream-colored or yellow, with numerous, irregularly spaced half-moon markings or spots that are orange or red, bordered with gray or black. The number of dark bands and blotches on the back is usually 30 or more. It lives in a wide variety of aquatic habitats.
- The midland watersnake subspecies (N. s. pleuralis) is tan or reddish brown; the crossbands and blotches are brown or reddish brown. Some individuals are orangish with brown markings. The belly is usually yellow with irregularly spaced orange, red, or brown spots or half-moon markings. The number of dark bands and blotches on the back is usually 30 or less. It prefers clear, cool, gravel-bed streams and is the most commonly encountered snake of southern Ozark streams.
- Missouri has four other species of watersnakes (Nerodia spp.), but the northern and midland watersnakes are the most commonly encountered. Pay attention to the color patterns to distinguish them from the others, including the northern and midland watersnakes' relatively colorful belly markings. In southeastern Missouri, the broad-banded watersnake has no more than 20 bands or blotches on the back, which are separated by yellow or yellowish gray, while the midland watersnake has more than 20 and is more tan, brown, orange, or reddish.
- Watersnakes are confused with the venomous northern cottonmouth (Agkistrodon piscivorus) and killed because of unwarranted fear. Cottonmouths are heavier-bodied with a larger, chunky head; have a pit between the nostril and eye; are darker; and have a light line from each eye to the corner of the mouth.
Adult length: 22 to 42 inches; occasionally to 59 inches.
Together, our two subspecies of common watersnake are found statewide. The northern watersnake subspecies is found throughout the northern and western majority of the state. The midland watersnake subspecies lives in the southeastern third. Where the ranges overlap, the two interbreed and intergrade.
Habitat and Conservation
This is Missouri’s most common species of watersnake. They are active from early April into October in our state. Individuals bask on branches overhanging water or on logs or rocks along the water’s edge. In hot weather, they become nocturnal. They hide under rocks or other objects along the edge of rivers and ponds. Riprap rock used to stabilize banks and levees are good habitat for both basking and hiding.
They live in and near a wide variety of aquatic habitats. Natural and human-made habitats include creeks, rivers, sloughs, ponds, lakes, and swamps.
This species overwinters in rock dams, levees, bank burrows, crayfish burrows, old logs and stumps, and crevices in rock ledges.
Watersnakes eat small fish; they also eat frogs, tadpoles, toads, and salamanders. Game fish are too agile for watersnakes to catch, unless the fish is injured or diseased. Northern watersnakes will also readily feed upon disposed carcasses of cleaned fish when anglers are preparing their catch. This happens, for instance, in heavy recreational use areas such as the Lake of the Ozarks.
Nonvenomous semiaquatic snake. This species is one of the most common snakes in Missouri, in appropriate habitats.
People frequently misidentify watersnakes as venomous species and kill them out of fear.
Even people who correctly identify watersnakes sometimes persecute them out of the mistaken belief that they eat game fish. In fact, watersnakes actually improve fishing by reducing the spread of fish diseases, reducing fish overpopulations, and by feeding large game fish, which eat young watersnakes.
Courtship and mating mainly occur April into June. Gestation may last about 2–4 months. Females give birth to live young in August and September. A litter can contain 6–99 young, usually averaging 27. Larger females usually produce more young per litter. Males become sexually mature within two years of life, females in three. Lifespan may be more than nine years.
Watersnakes were formerly killed under the mistaken belief that they ate game fish. In reality, they improve fishing by eating dead or dying fish (preventing the spread of fish diseases), by reducing fish overpopulation, and by providing food for game species (large game fish eat young watersnakes).
Watersnakes are a natural part of our outdoor heritage and a valuable component of the waters of our state.
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.