The cottonmouth is named for the cotton-white color of the inside of its mouth. This will sometimes be displayed in an open-mouthed threat before the snake strikes. If the large animal or human backs slowly away when thus threatened, the cottonmouth may not strike at all. This is because venom is necessary in order for the snake to obtain food. It takes time to replenish the venom supply, so a cottonmouth will often avoid envenomating an animal too large for it to swallow. Cottonmouths prefer to escape from danger if at all possible, but don't seem to fear humans as much as other snakes.
When attacking a potential meal, cottonmouths use a method called "strike and hold". This is because cottonmouths do much of their hunting in or near water and it is impossible to follow the prey's scent trail underwater. Also, the cottonmouth diet consists mainly of fish and frogs. It is unlikely that these animals could injure the snake, so there is no need to strike and retreat. Young cottonmouths use the bright yellow tips of their tails to attract prey, but the yellow tip darkens with age.
Cottonmouths mate soon after emerging from hibernation in early spring. Males sometimes fight for breeding rights. The loser moves away and the winner begins the mating ritual with the female. Cottonmouths are ovoviviparous. The female retains the eggs in her body until they are ready to hatch. Brood size varies widely from one to sixteen. Young cottonmouths are able to hunt immediately and receive no care at all from the female, which leaves the brood as soon as it is delivered.
Cottonmouths are widely spread throughtout south central and southeast U.S., but their range in Illinois is limited to the southernmost tip of the state. Because of their habitat, they do not come into contact with humans too often. Cottonmouths live mainly in swamps and near slow-moving bodies of fresh water. There they ambush their aquatic prey from branches or rocks above the water.
Cottonmouths use their highly cryptic coloration in their hunt for food and as protection from predators.
People sometimes mistake non-venomous water snakes for cottonmouths and refer to all similar snakes as "water moccasins". Out of fear, many people kill them indiscriminately.
