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Scientific name: Agkistron contortrix
Common name: 
Copperhead Snake

(Information in this Species Page was compiled by Rebecca Young in Biology 220W, Spring 2003, at Penn State New Kensington)

Copperheads (Agkistron contortrix) get their names, quite logically, from their un-marked, copper-red colored heads. Copperheads have light-brown, or orange, or pink bodies that are highlighted by dark, chestnut brown cross bands which form a series of hourglass shapes across their backs. The thickness and continuity of these cross bands are important characteristics in identifying the five sub-species of A. contortrix. Belly markings of these snakes consist of gray to black blotches that are blended together to make a cloudy or marbled pattern. Copperheads are typically 2 to 3 feet in length although individuals up to 4 ½ feet long have been reported. Females are longer than males, but males have proportionally longer tails. The bodies of A. contortrix are stout and taper abruptly to form the much smaller diameter tail. Immature copperheads have tails that are bright yellow, and they may use these colored tails to attract prey.

Copperheads are found throughout the eastern and central United States from Connecticut to Kansas and Florida to western Texas. The five sub-species are roughly distributed in a northern, northwestern, southern, and two southwestern sub-regions of their broad geographic range.

Copperheads can thrive in a variety of habitats including rocky, wooded areas, wood and sawdust piles, mountains, brushy zones along streams and creeks, abandoned farm buildings and old foundations, junk yards, swamps, brush piles, and desert oases and canyons. Copperheads are usually solitary except during their mating season. They do hibernate in communal dens, though, not only with other copperheads but also with snakes of a variety of species (including rat snakes and rattlesnakes). In the spring and fall copperheads can be frequently seen during the day, but in the warm summer months they are primarily nocturnal. Humid, warm nights, especially nights after a rain, are ideal times to see active copperheads.

Mating and Reproduction
Males fight for the right to mate with females. Males who lose a mating contest are not likely to ever challenge another male again. Females also may fight prospective mates and will not mate with an individual who backs down from an initial encounter. The outcomes, then, of these mating fights are extremely important selective pressures that determine the surviving or succeeding genes and behaviors in the A. contortrix population.

Copperheads mate in the late spring or early fall. Females are able to store sperm (often from a variety of different males) and defer the fertilization of their eggs for extended periods of time. Ovulation and fertilization usually occur in the spring. In the fall, a female will give birth to 1 to 14 young usually near her established hibernation den. Larger females give birth to greater numbers of young. The young are born live, encased in a thin membrane from which they quickly emerge. The development of this type of “live” births (termed “ovoviviparous” reproduction) reduces the exposure of the egg encased embryos to both predation and environmental damage. The young copperheads are 8 to 10 inches long and are born with both fangs and venom. The young snakes may even take prey in the weeks remaining before they must enter the hibernation den for the winter.

Copperheads are pit vipers (Family Viperidae). Their facial pits are heat sensory structures located between their eyes and nostrils. These pits are used to detect and accurately strike their warm-blooded prey. Copperheads eat many species of rodents (mice, chipmunks etc), frogs, lizards, other snakes, small birds, and even insects (especially large caterpillars and cicadas). An individual snake may eat only 10 or 12 meals a year (depending on the size of the prey taken). After locating its prey by both olfaction and heat sensation, the snake strikes and injects the animal with venom. The venom breaks down blood cells and leads quickly to circulatory collapse. The snake then swallows its prey whole (a task facilitated by its loosely hinged jaws) and relies on its powerful digestive secretions to break down all parts of the swallowed organism (including bones and fur).

Bite of a Copperhead
The bite of a copperhead is extremely painful but is not, usually, life threatening for a healthy adult. Children and pets and individuals with compromised immune systems, though, may have serious reactions to the venom. Copperheads bite more people in the United States than any other venomous snake, so it is fortunate that their venom is so mild. Copperheads, unlike most other venomous snakes, strike almost immediately when they feel cornered or threatened. Rattlesnakes and cottonmouths, for example, go through obvious auditory and visual warning displays prior to striking. The rapid strike of the copperhead is actually thought to be a consequence of a lunging, warning display that, unfortunately for the victim, too often occurs when the snake and the disturbing individual are close to each other. The lunging snake, then, makes contact with the victim, pierces the skin with its fangs, and only incidentally injects a very tiny amount of venom into the bite. A bite from a copperhead is a serious medical event! Medical attention is required by anyone bitten by a copperhead!

The venom of the southern sub-species of copperhead contains the chemical called “contortrostatin.” It has the potential to be used to control blood vessel formation in cancerous tumors. Breast cancers in mice, for example, treated with contortrostatin grow at a rate that is but 1/3 of the growth rate of tumors that have not been treated with the drug. This is another example of the application of the chemical diversity of nature to the needs and uses of human beings.

There are many myths about copperheads. One that has come up for me in a variety of conversations and emails concerns the interbreeding of copperheads and black rat snakes to form a new, very active, venomous hybrid snake. The good news is that this cross-species breeding is not biologically possible. These two snake species are, in fact, in different taxonomic families! The chance of these two species successfully interbreeding is as likely as a human being producing viable offspring after mating with a lemur, or a dog being able to hybridize with a house cat! This myth possibly came about because of the previously mentioned observation that black rat snakes and copperheads often den together during hibernation. There is a big difference, though, between communal denning and reproducing!

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