Identification

This harmless snake is ubiquitous throughout streams, ponds, lakes, and wetlands in Indiana and is frequently mistaken for the venomous "water moccasin" or cottonmouth. Common Watersnakes are incredibly variable with some individuals displaying mahogany red bands on a background of silver-gray and others, dark brown to the point of appearing nearly uniformly black from a distance. Juveniles are light gray with black to dark brown bands that usually become brown to reddish with age. Common Watersnakes, though not quite as large as Indiana's other watersnakes, are robust snakes that may reach nearly five feet (1.5 m) in length.

This snake is probably one of the most frequently misidentified in Indiana as many other brownish gray snakes have banded patterns. It's important to note that, in Indiana, cottonmouths are only known from two sites and may now be extirpated from both. However, the two can be easily differentiated as cottonmouths are more heavy-bodied, have broad, chunky heads, are almost uniformly dark as adults, have bright yellow tail tips as juveniles, and have a distinctive, broad black stripe through the eye. Copperheads are more similar in appearance, but favor drier environs. They also have a distinctive hourglass-shaped bands, when viewed from above, as opposed to the irregular blotches and bands of Common Watersnakes. Eastern Milksnakes, Prairie Kingsnakes, and Western Foxsnakes have a similar banded pattern, but watersnakes are more robust and have heavily keeled ("rough") scales. The Diamond-Backed Watersnake is found alongside this species in southwestern Indiana, but has a distinctive chain-linked "diamond" pattern, instead of bands or blotches. Plain-Bellied Watersnakes also occur alongside Common Watersnakes but adults are nearly black dorsally with a brilliant orange underbelly. Juveniles have bands similar to those of Common Watersnakes, but lack the blotches and checkers that mark the venter of Common Watersnakes.

The two subspecies of the Common Watersnake are teh the Midland Watersnake (N. s. pleuralis) and the Northern Watersnake (N. s. sipedon); these two look very similar, except that the dark bands (usually fewer than 30) on the Midland Watersnake's back are narrower than the lighter spaces between them, while the dark bands of the Northern Watersnake are wider than the light ones.

Ecology and Conservation

This aquatic snake’s diet consists mainly of various small-sized fish, frogs, toads, and salamanders. The Common Watersnake is almost always found in or adjacent to water. It prefers slow flowing water, but can easily swim and maneuver in strong currents. When disturbed or threatened it can be very aggressive and will strike out. This snake will sometimes release a musky-smelling substance when it is handled. The Common Watersnake, found statewide, is sometimes killed because it is mistaken for the venomous cottonmouth, which is only found in the extreme southern portion of the state. While the Common Watersnakes prey upon fish, they have little impact on sport fishing. They eat mostly small, slow-moving or injured fish.

The Northern and Midland subspecies are generally common throughout their range. The Lake Erie Watersnake is endemic to the islands of the Put-in-Bay Archipelago off the northern shore of Ohio. It is listed as State Threatened in Ohio.

Distribution

Common Watersnakes are found throughout Indiana and are, undoubtedly, the most frequently encountered snake around any body of water in the state. Though they are abundant along rivers and wetlands, these watersnakes adapt well to man-made environments and readily colonize small ponds and utilize rip-rap and concrete structures along dams and canals. Northern Watersnakes (N. s. sipedon) are distributed across the northern half of the state, while Midland Watersnakes (N. s. pleuralis) are distributed across the southern half of the state; many animals in the middle of the state appear intermediate between these two subspecies.

Taxonomy

Two subspecies of the Common Watersnake (Nerodia sipedon) are found in Indiana--the Northern Watersnake (N. s. sipedon) and the Midland Watersnake (N. s. pleuralis). These snakes are members of the family Colubridae, which is represented by a total of 28 species in Indiana.

Literature Cited

Conant, R. and J. T . Collins. 1998. Reptiles and Amphibians of Eastern and Central North America. Third Edition, Expanded. Houghton Mifflin, New York, NY.

Minton, S. A. Jr. 2001. Amphibians and Reptiles of Indiana. Indiana Academy of Science, Indianapolis, IN.