Cottonmouth : North Carolina wildlife profiles

Cotton mouth ( Agkistrodon piscivorus ) Photo byjeff Hall Also known as the water moccasin, the cottonmouth derives its common name from the white color of the inside of its mouth, which is revealed when the snake gapes to defend itself. Two species of the genus Agkistrodon occur in the United States, the cottonmouth and the copperhead (A. contortrix). Both occur in North Carolina. There are three subspecies of cottomnouth. The subspecies in North Carolina is the Eastern cottomnouth (Agkistrodon piscivorus piscivorus). Along with copperheads and rattlesnakes, the cottomnouth is a member of the viper family (Viperidae). Its venom toxicity ranks fourth of the six species of North Carolina venomous snakes (after the coral snake, eastern diamondback ratdesnake and timber rattlesnake). Description The venomous cottonmouth, like all pit vipers, has a facial pit for sensing infrared radiation (heat), but unlike rattlesnakes, it lacks a rattle. The head is distinctly wid¬ er than the neck, with a dark bar on both sides from the eye to the angle of the jaw. There are nine large scales on the crown of the head, and the pupils of the eyes are vertically elliptical. The cottonmouth is patterned with dark crossbands invaded by light olive or brown centers. These dark crossbands are widest on the sides of the animal and narrowest on the top. This is the opposite of most nonvenomous water snakes that may resemble cottonmouths superficially (in water snakes, the dark crossbands have the widest part of the band on the top). Juveniles have bright yel¬ low or greenish tail tips, and the details of the crossband pattern are most evident in this age group. Older individuals are often completely dark and unpatterned. History and Status The cottomnouth is common in eastern North Carolina. The cottonmouth is not on federal or state species protection lists. However, as development increases in eastern North Carolina, loss of habitat could affect cottonmouth populations. Habitats & Habits The cottonmouth is the most aquatic of North American venomous snakes and can be found in most habitats associated with water. Like other ectothermic (“cold-blooded”) reptiles, cottonmouths bask on branches, logs or stones at the water’s edge. They are most active at night and become inactive at the onset of cold weather, brumating underground over winter. Common hibernacula are on rocky wooded hillsides, in crayfish burrow's, under rotting stumps and in mammal bur rows. If approached, some cottonmouths will retreat but others are defensive and will stand their ground. They often coil, vibrate their tail and open their mouth to reveal the white inner lining. The cottonmouth is named for the white color inside its mouth Adult cottonmouth (Photo: Jeff Hall) Range and Distribution Cottonmouths range from southeastern Virginia through eastern North and South Carolina, south to Florida, west to Texas, and north along the Mississippi River to southern Illinois and Indiana. The Eastern cottonmouth is restricted to Virginia, North Carolina, South Carolina, Georgia, Florida and Alabama. In North Carolina, cotton¬ mouths are predominantly found in the Coastal Plain and on some parts of the Outer Banks. In a few places, they are the most abundant snake species. Pre-1900 records also exist from the lower Piedmont, but the Wake County sightings reported each year are superficially similar nonvenomous water- snakes (Nerodia). Range Map ■ Cottonmouth Range Map