This harmless snake is ubiquitous throughout streams, ponds, lakes, and wetlands in Indiana and is frequently mistaken for the venomous "water moccasin" or cottonmouth. Northern 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. Northern 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 Northern 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 Northern Watersnakes but adults are nearly black dorsally with a brilliant orange underbelly. Juveniles have bands similar to those of Northern Watersnakes, but lack the blotches and checkers that mark the venter of Northern Watersnakes.
Ecology and Conservation
This aquatic snake’s diet consists mainly of various small-sized fish, frogs, toads, and salamanders. The Northern 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 Northern 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 Northern 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.
Northern 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.
Three subspecies occur in the Midwest. The Midland Watersnake (N. s. pleuralis) looks very similar to the Northern Watersnake (N. s. sipedon), except that the dark bands (usually