Summer/Fall 2001

Species Profile: Cottonmouth

Beginning with dove season and continuing through to squirrel season and part of the beginning of deer season, we are spending more time in the outdoors. With this increase in activity, the potential encounters with reptiles increases.

Included among the many reptile species of Mississippi is the cottonmouth (Agkistrodon piscivorous). It derives it's name from the white inner-mouth which is commonly exposed when the snake is threatened.

The cottonmouth is a very heavy bodied, large pit viper, usually 30 to 42 inches in length and is one of the most abundant snakes found in the South. Adult cottonmouths found in the Delta are of the Western subspecies (A. piscivorous leucostoma) and are olive, dark brown or black in color. Cottonmouths found outside the Delta are of the Eastern subspecies (A. piscivorous piscivorous) and the adults are usually a light brown to tawny yellow color with light faces.

Juvenile cottonmouths of either subspecies are generally lighter in color than the adults with a predominant crossband pattern. Coloration is generally reddish crossbands on a pink or rusty ground color with yellow to greenish tails. These bright bands are often used to lure small animals. Due to the coloration and banding of juveniles, they are commonly mistaken for copperheads. As juveniles continue to age they lose these characteristics and after two or three years acquire the coloration of adults.

Cottonmouths live in almost any type of wetland from brackish marshes to streams, ponds, lakes, rivers and cypress swamps and bayous. Occasionally, these snakes are found on land away from any permanent water source, but they are most commonly associated with water.

During spring and fall, cottonmouths are very active during daylight hours, predominantly during early morning and late afternoon. During summer, when temperatures become extremely hot, they become nocturnal and move frequently under the cover of darkness, during cooler temperature.

Breeding usually takes place in August and September and the offspring are born one year later. After breeding, cottonmouths begin to leave their aquatic habitat for adjacent upland areas where hibernation will take place. Usually by November, cottonmouths have totally disappeared from aquatic areas.

Cottonmouths are opportunistic feeders. Dead or diseased fish make up most of their diet, but these snakes will also feed on small mammals, birds, insects, frogs and small snakes of other species.

According to Terry L. Vandeventer, a professional herpetologist, contrary to popular belief, cottonmouths are not aggressive snakes. They are, however, extremely defensive.

"In many instances cottonmouths will retreat at the approach of a human, but when an encounter cannot be avoided, the snake will defend it's ground," stated Vandeventer. "When a snake is encountered the best thing to do is leave it alone. Take two steps backward and go out of your way to avoid the snake."

This article was written by Rob Ballinger, Field Biologist of the Mississippi Fish and Wildlife Foundation.