Is has been suggested that the cottonmouth is North America’s most aggressive snake (14) because it frequently stands its ground if threatened (3). When threatened, this species first tries to escape before using defensive behaviour such as mouth gaping, tail vibrations, odour-release and, eventually, striking and biting (15). It is thought that tail vibrations are used to mimic the warning behaviour of the closely related rattlesnake (14).
The cottonmouth is active during the day or at night, and in much of its range it can be seen all year round (2), except in cooler areas where it hibernates (13).
This well-camouflaged, highly venomous ambush predator generally forages at night when temperatures are cooler (16). Coiling into a ‘strike’ position, it waits for prey to pass, before biting and releasing its victim. The cottonmouth then follows the scent of its stricken prey, waiting for it to die before swallowing it head first (3). Cottonmouth venom causes tissue damage, kidney failure and cardiac arrest in its victims due to the fast-acting enzymes and proteins (17).
An opportunistic, generalist feeder (18), the cottonmouth eats fish, arthropods, reptiles, amphibians and mammals. Like other snakes, prey selection of cottonmouths is limited by the size of its mouth, resulting in a difference in diets between adults and juveniles (19).
Large adult cottonmouths have few predators, although snapping turtles, alligators, large wading birds and owls may feed on them (3). Adult cottonmouths are cannibalistic and are known to eat juveniles (13) (18).
In late August to September, the female cottonmouth gives birth to six to eight live young, which are fully-formed and full of venom (3).