Northern Watersnake

Media
Photo of a northern watersnake rearing back in grass on land.
Scientific Name
Nerodia sipedon sipedon
Family
Colubridae (nonvenomous snakes) in the order Squamata (lizards and snakes)
Description

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.

Similar species:

  • 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.
Common Name Synonyms
Northern Water Snake
Banded Watersnake
Common Water Snake
Midland Watersnake (ssp. pleuralis)
Size

Length: 24 to 42 inches.

Where To Find
Northern Watersnake Distribution Map

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.

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.

Life Cycle

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.

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Similar Species

Where to See Species

This access provides wade fishing and float fishing access to the Niangua River. Both brown trout and rainbow trout are stocked in portions of the Niangua River.
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.