The cottonmouth, or water moccasin (Agkistrodon piscivorus), is a semi-aquatic pit viper native to the wetlands of the southeastern United States. This species thrives in swamps, marshes, and slow-moving bodies of water, occupying an important ecological role as an adaptable predator. Its name, which translates roughly to “fish eater,” hints at its preferred environment and general diet. This snake is a venomous hunter whose food sources reflect its close association with diverse aquatic and terrestrial habitats.
The Broad Diet of the Cottonmouth
The cottonmouth is an opportunistic carnivore known for its generalist feeding habits, consuming nearly any prey item it can successfully subdue and swallow. Aquatic life forms the bulk of the adult snake’s diet, most notably fish and amphibians. Fish, such as catfish and bass, are primary targets, especially when concentrated in drying water bodies. The snakes also consume amphibians like frogs and salamanders, including common species such as southern leopard frogs.
The snake’s diet extends beyond the aquatic realm to include reptiles, small mammals, and birds. They prey on lizards, small turtles, and sometimes the eggs of ground-nesting birds. Other snakes, including non-venomous water snakes and even smaller cottonmouths, are regular prey items, demonstrating a tendency toward cannibalism. Small mammals, such as shrews and rodents, are incorporated into the diet as the snake forages on land near the water’s edge. This wide-ranging menu establishes the cottonmouth as a significant predator capable of exploiting multiple food webs.
Specialized Hunting Tactics
The cottonmouth employs several distinct methods to capture its diverse range of prey, utilizing both passive and active strategies. One common technique is ambush predation, where the snake waits motionless at the water’s edge or concealed in vegetation until a suitable animal wanders within striking distance. For larger prey, the snake strikes, injects venom, and then releases the animal, following its scent trail until the venom takes effect. For smaller prey, they may simply hold the animal until it ceases to struggle.
Uniquely among North American snakes, the cottonmouth is one of the few species known to readily consume carrion. They are often attracted to the scent of dead fish, allowing them to scavenge easy meals, particularly where fishing activity is common. Juveniles employ a specialized method called caudal luring, where they wiggle their bright yellow or greenish tail tip to mimic a worm or insect grub. This movement attracts small, visually oriented prey, such as frogs and lizards, directly toward the hidden snake.
How Diet Varies by Age and Habitat
A cottonmouth’s diet changes significantly as it grows, reflecting a shift in hunting ability and size preference. Juvenile snakes, which are smaller, initially rely heavily on prey such as insects, small frogs, and small lizards, often captured using caudal luring. As they mature, snakes transition to larger, more substantial meals, including adult fish, rodents, and larger amphibians. This size-dependent shift is important for energy intake and growth.
The specific composition of the diet is also directly influenced by the snake’s local habitat. The species’ scientific designation, piscivorus, highlights the importance of fish, which are more readily consumed in areas with permanent, open water. Snakes living in coastal marshes or inland swamps will show higher consumption rates of the most available local prey, whether that is fish in a riverine environment or small mammals in a heavily wooded swamp. Studies have noted differences between sexes, with adult males often consuming more fish, while adult females sometimes prey on other squamates, including other snakes, more frequently.