The northern watersnake is a gray to reddish-brown snake with numerous dark brown, reddish-brown, or blackish crossbands along the front third of the body. It is frequently misidentified as a cottonmouth. The bands become blotches in the latter part of the body. The belly is cream-colored or yellowish with numerous black and reddish half-moon markings or spots. As with other watersnake species, the scales along the back have keels, causing the snake to feel rough. For defense, watersnakes bite viciously (but they are not venomous) and secrete a strong-smelling musk from glands at the base of the tail.
- The midland watersnake (N. sipedon pleuralis), another subspecies, occurs in the southern third of Missouri. It is tan or reddish brown with brown or reddish-brown bands. Some are orangish with brown markings. It prefers clear, cool, gravel-bed streams. The subspecies overlap and interbreed, so some show traits of both.
- Watersnakes are confused with the venomous northern cottonmouth (Agkistrodon piscivorus) and needlessly killed. 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.
Length: 24 to 42 inches.
Found throughout the northern and western two-thirds of the state. The midland watersnake subspecies lives in the southern and eastern third. The two overlap and intergrade.
Habitat and Conservation
This is Missouri’s most common species of watersnake. Individuals bask on branches overhanging water or on logs or rocks along the water’s edge. In hot weather, they are nocturnal. They hide under rocks or other objects along the edge of rivers and ponds. They live in and near a wide variety of aquatic habitats: creeks, rivers, sloughs, ponds, lakes, and swamps.
Watersnakes eat fish (mostly nongame species), frogs, tadpoles, toads, and salamanders. Game fish are too agile for watersnakes to catch, unless the fish is injured or diseased.
Locally, this snake is sometimes called “banded water snake” or “common water snake.” More confusing yet, there is another species of watersnake (Nerodia fasciata confluens) that is officially called broad-banded watersnake. Herpetologists create official common names that correspond precisely with scientific names. Because these official common names and the common names used by regular people don’t always agree, it is best to use scientific names when identification must be precise.
This species is active from early April until October. Courtship and mating occur in the spring, and gestation may last 3-4 months. The young are born live during August and September. A litter can contain 6-66 young, usually averaging 20-25. The young are light gray or tan, contrasting with dark brown or black crossbands and blotches, and at birth they are about 7-10 inches long. Some females may produce a litter every other year.
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).
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.