Snake Biology

Identification | Biology | Damage ID | Management | Handling


Snakes typically mate in the spring. Female snakes may lay eggs, retain membrane-covered eggs inside the body during incubation, or give birth to live young. Eggs hatch and young are born in late June through early fall depending on latitude and species. Young copperheads, rattlesnakes, and cottonmouths are retained in the body of the female during incubation and are born within a transparent egg sack during late summer or early fall. Juveniles of species that are venomous are just as venomous as adults. 

Denning Cover 

Snakes do not nest. They seek locations for protection and thermoregulation. For example, a sun-exposed rock provides warmth and a rock wall provides protection and cool temperatures. Underground dens, or hibernacula, protect snakes from freezing temperatures. Hibernacula form around structures including sump pumps, rock walls, basements, crawl spaces, and other locations that are safe from winter freezing. A single hibernaculum may contain multiple species and hundreds of snakes.  


The behavior of snakes is determined more by temperature than by season. Snakes become lethargic at temperatures below 50°F. In most cases, snakes will move away when approached. Snakes do not charge or attack people, with the exception of racers that usually enter a state of panic and engage in a behavior called “periscoping,” in which they lift their head above the grass to look for danger and then duck down. On rare occasions, racers will bluff by advancing toward an intruder, though they retreat rapidly if challenged. Snakes react when cornered with a variety of defensive tactics that vary by species. Defensive tactics include playing dead by exposing the belly, hissing, opening the mouth in a menacing manner, coiling, emitting an odorous fluid from the vent, striking, and biting.  


Snakes are not very mobile. Some are fairly adaptable, but most have specific habitat requirements. Some species live underground while others, such as green snakes, primarily live in trees. Generally, snakes live in cool, damp, dark areas where prey is available. Areas around the home that are attractive to snakes include piles of firewood, old lumber, and junk; flower beds with heavy mulch; gardens; basements; shrubbery growing against foundations; barn lofts, especially where feed attracts rodents; attics in houses with rodents or bats; banks of streams and ponds; lawns with long grass; and abandoned lots and fields with boards, tires, and planks.  

Food Habits 

All snakes are predators, and different species eat a variety of sizes and kinds of animals. Rat snakes primarily eat rats, mice, chipmunks, eggs of birds, and baby birds. King snakes eat other snakes, rodents, young birds, and eggs of birds. Some snakes, such as green snakes, primarily eat insects. Some small snakes, such as earth snakes and worm snakes, eat earthworms, slugs, and salamanders. Water snakes primarily eat fish, frogs, and tadpoles.