The cottonmouth, also known as the water moccasin, is a large, semi-aquatic snake belonging to the pit viper family (Viperidae) and is native to the United States. This species, scientifically named Agkistrodon piscivorus, is one of the few venomous snakes that spends much of its time in aquatic environments. As a pit viper, it possesses heat-sensing facial pits and hinged fangs used to deliver venom. The cottonmouth is a prominent reptile in the Southeast, occupying a wide variety of wetland ecosystems.
Geographic Range of the Cottonmouth
The overall distribution of the cottonmouth encompasses a large portion of the Southeastern United States, extending its range across multiple states. Its northern limit generally reaches southeastern Virginia along the Atlantic coast, moving southward through the Carolinas, Georgia, and all of Florida. Moving westward, the snake is found throughout the Gulf Coast states, including Alabama, Mississippi, and Louisiana. The distribution continues into the eastern half of Texas and northward along the Mississippi River Valley. This river system provides a corridor, extending its presence into states like Arkansas, Tennessee, Kentucky, southern Illinois, and Indiana.
Specific Habitat Preferences
Cottonmouths are classified as semi-aquatic, indicating a life spent both in and out of the water, though they are rarely found far from a water source. They exhibit a strong preference for slow-moving or stagnant aquatic environments, such as swamps, marshes, and cypress swamps, where they hunt and seek shelter. Drainage ditches, sluggish streams, and the edges of lakes or ponds are also common locales. The presence of dense vegetation, debris, or thick banks is important for providing basking opportunities and cover from predators. Cottonmouths are frequently observed coiled on logs or leaf litter right at the water’s edge, allowing them to quickly enter the water if disturbed. They tolerate brackish water, meaning they can sometimes be found in coastal environments like salt marshes or estuaries.
Identifying the Cottonmouth
Proper identification of the cottonmouth is important for safety, as it is often confused with harmless non-venomous water snakes. The cottonmouth is a heavy-bodied snake with a thick, muscular build, typically ranging from two to four feet. Its head is notably large and triangular or spade-shaped, distinct from its narrower neck. A key physical trait is the presence of elliptical, cat-like pupils and a deep, heat-sensing pit located between the eye and the nostril. When threatened, the snake opens its mouth wide to reveal a stark, pale white interior, which is the origin of its common name. Adult coloration is highly variable, ranging from dark brown or black to an olive color, with crossbands that may become obscured as the snake ages. Juveniles possess bright, distinct crossbands and a conspicuous sulfur-yellow tip on their tails.
Seasonal Movements and Safety
Cottonmouth activity is closely tied to the seasons, concentrating on finding food and regulating body temperature. During the warmer spring and summer months, they are most active, frequently basking in sunny spots along the water’s edge. They often become more nocturnal during the hottest parts of the summer, hunting for fish, amphibians, and small mammals. As temperatures drop in the fall, cottonmouths seek out suitable sites for brumation, a state of winter dormancy. They move away from the water into terrestrial refuges, often using underground locations such as crayfish burrows, hollow logs, or rock crevices near the water line. Safety involves being observant of the immediate surroundings and maintaining distance from any snake encountered. Wearing thick, protective footwear, such as rubber boots, in swampy or marshy areas is a prudent measure.