The cottonmouth, also known regionally as the water moccasin, is a highly recognizable venomous snake inhabiting the southeastern United States. This species, scientifically named Agkistrodon piscivorus, belongs to the pit viper family, defined by heat-sensing facial pits between the eyes and nostrils. Cottonmouths are semi-aquatic, spending significant time both on land and in freshwater environments. Their common name comes from the bright, pale-white interior of their mouth, which they display as a defensive warning.
The Definitive Answer and Geographic Range
Cottonmouths are found in Kentucky, but their distribution is extremely limited within the state’s borders. They are not a statewide species and are restricted to the westernmost region, specifically the area known as the Jackson Purchase. This geographic restriction places the cottonmouth primarily in the counties that border the Mississippi and Ohio Rivers. Their range also extends slightly into the Western Coalfields region. The snake’s range terminates sharply, making it a species of concern only for those living or recreating in the state’s far western lowlands near swamps, sloughs, and floodplains.
Key Differences From Look-Alikes
The primary source of confusion is the harmless Northern Water Snake (Nerodia sipedon), which is abundant statewide and often mistaken for the venomous cottonmouth.
A cottonmouth is a pit viper, possessing a broad, blocky, and triangular head that is distinctly wider than its neck. The pupils of the cottonmouth are vertical, resembling a cat’s eye, while the non-venomous water snake has round pupils. Cottonmouths also possess deep facial pits, located between the eye and the nostril, a feature absent in water snakes.
When swimming, the cottonmouth typically holds its entire body on top of the water’s surface, appearing to float high. Conversely, water snakes swim with only their head visible above the water line.
While head shape is a common identification cue, harmless water snakes often defensively flatten their heads to mimic the triangular shape. However, the cottonmouth is significantly more heavy-bodied and thick compared to the generally more slender water snake. Juvenile cottonmouths also have a bright, yellowish-green tail tip that they use to lure prey.
Habitat, Behavior, and Encounter Safety
Within their limited Kentucky range, cottonmouths favor sluggish, shallow, and dark bodies of water, including swamps, marshes, sloughs, and river floodplains. They are often found basking on logs, low branches, or banks near the water’s edge. They can occasionally be found in upland areas during seasonal movements to and from hibernation sites. They hunt fish, amphibians, and small mammals both in and out of the water, primarily during the night in warmer months.
When threatened, the cottonmouth exhibits its defensive display by coiling its body and opening its mouth wide to reveal the startling white lining. This is a clear warning sign that should be respected. They may also vibrate their tail rapidly, similar to a rattlesnake, which can create a buzzing sound in dry leaves.
The best safety practice is to maintain a respectful distance from any snake encountered near water, especially in the western counties. Never attempt to handle or harass a cottonmouth, as bites almost always occur when a person tries to move or interact with the snake. Wearing sturdy, closed-toe footwear and watching where you step when near swampy or marshy areas minimizes the risk of an accidental encounter.