The venomous Water Moccasin, also known as the Cottonmouth (Agkistrodon piscivorus), is definitively not found in New York State. This heavy-bodied, semi-aquatic pit viper is commonly associated with the swamps and bayous of the southeastern United States. Its appearance and reputation often lead to mistaken identity with harmless species found much further north.
Geographical Range and Habitat Requirements
The natural geographical range of the Water Moccasin extends only as far north as southeastern Virginia, and in the Midwest, a few isolated populations are found in southern Illinois and Missouri. New York lies far outside this established territory. The boundary of its range is primarily limited by climatological factors, particularly the length of the growing season and the duration of cold temperatures in winter.
New York’s colder climate and shorter warm season are not suitable for the Cottonmouth’s reproductive cycle and long-term survival. As a cold-blooded reptile, the snake requires a specific thermal environment to thrive and reproduce effectively. The prolonged freezing temperatures of a New York winter prevent the establishment of stable, self-sustaining populations.
The Northern Water Snake Confusion
The common inquiry about Water Moccasins in New York stems from the abundance of the non-venomous Northern Water Snake (Nerodia sipedon). This common snake is often mistaken for its venomous southern counterpart due to its dark coloration and aquatic habits. The Northern Water Snake is highly prevalent across the state, inhabiting nearly any freshwater environment, including lakes, ponds, rivers, and marshes.
The confusion is heightened by the Northern Water Snake’s defensive behavior, which can appear aggressive when threatened. When cornered, it may flatten its head and body to look larger, sometimes causing its head to appear triangular, superficially mimicking a pit viper’s head shape. This snake will readily bite if handled, although its bite is not venomous.
Distinguishing the two species involves several clear features. The Cottonmouth is a pit viper with a distinctly blocky, triangular head, a narrow neck, and vertical, cat-like pupils. In contrast, the Northern Water Snake has a more slender head that is not distinctly wider than its neck, and it possesses round pupils. When swimming, the venomous Cottonmouth typically floats with its entire body exposed on the water’s surface, while the harmless water snake swims with its body submerged, with only its head above the water line.
Native Venomous Snakes of New York
Although the Water Moccasin is absent, New York State is home to two primary venomous snake species: the Timber Rattlesnake (Crotalus horridus) and the Eastern Copperhead (Agkistrodon contortrix). Both are pit vipers, meaning they possess heat-sensing pits between their eyes and nostrils.
The Timber Rattlesnake is a large, heavy-bodied snake found mostly in the southeastern portion of the state, with populations extending north to the Lake George region and along the Southern Tier. This species prefers rugged, mountainous terrain and rocky ledges, where it hibernates communally.
The Eastern Copperhead is less common and is primarily restricted to the lower Hudson Valley region, south of Kingston, and parts of the Catskill Mountains. Copperheads often inhabit wooded hillsides, rocky outcrops, and wetlands, and they are recognized by their distinct hourglass-shaped, copper-colored crossbands. A third, much rarer venomous snake, the Eastern Massasauga (Sistrurus catenatus), exists in only two highly localized, boggy wetland areas in central and western New York, and its distribution is extremely limited.