Agkistrodon contortrix

Common names: copperhead (snake), chunk head, death adder, (dry-land) moccasin,^[2] more.

Agkistrodon contortrix is a venomous pitviper species found in North America. Five subspecies are currently recognized, including the nominate subspecies described here.^[3]

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Description

Adult specimens have a coppery colored head and neck. They are moderately sized snakes, with adults normally reaching 0.8–1.2 meters (2–4 feet), with thick, heavy bodies, although the body is more slender than most other pit vipers.

There are five clearly defined subspecies, all of which have distinctive light and dark brown or greenish banding: A. c. mokasen, A. c. contortrix and A. c. phaeogaster have bands that tend to narrow dorsally, giving them an hourglass shape, whereas A. c. laticinctus and A. c. pictigaster generally have bands of uniform width. The patterned underside of A. c. pictigaster, with its white and black banding, is especially distinctive. Intergrading occurs in areas where the geographic ranges of the subspecies overlap, and so pattern variations are commonplace.

Common names

Copperhead (snake), chunk head, death adder, highland moccasin, (dry-land) moccasin, narrow-banded copperhead, northern copperhead, pilot snake, poplar leaf, red oak, red snake, southeastern copperhead, white oak snake,^[2] American copperhead,^[4] southern copperhead,^[5] cantil cobrizo (Spanish).^[3]

Geographic range

Found in the United States in the states of Texas, Oklahoma, Kansas, Missouri, Arkansas, Louisiana, Mississippi, Alabama, Georgia, Florida, South Carolina, North Carolina, Tennessee, Kentucky, Virginia, West Virginia, Illinois, Indiana, Ohio, Iowa, Pennsylvania, Maryland, New Jersey, Delaware, New York, Connecticut and Massachusetts. In Mexico it occurs in Chihuahua and Coahuila. The type locality is "Carolina." Schmidt (1953) proposed that the type locality be restricted to "Charleston, South Carolina."^[1]

Habitat

Within its range it occupies a variety of different habitats. In most of North America it favors deciduous forest and mixed woodlands. They are often associated with rock outcroppings and ledges, but are also found in low-lying swampy regions. In the states around the Gulf of Mexico, however, it is also found in coniferous forest. In the Chihuahuan Desert of west Texas and northern Mexico, it occurs in riparian habitats, usually near permanent or semipermanent water and sometimes in dry arroyos.^[6]

Conservation status

This species is classified as Least Concern (LC) on the IUCN Red List of Threatened Species (v3.1, 2001).^[7] Species are listed as such due to their wide distribution, presumed large population, or because it is unlikely to be declining fast enough to qualify for listing in a more threatened category. The population trend is stable. Year assessed: 2007.^[8]

Behavior

Like all pit vipers, A. contortrix is an ambush predator: it takes up a promising position and waits for suitable prey to arrive. In the southern United States, they are nocturnal during the hot summer months, but are commonly active during the day during the spring and fall.

Like most North American viperids, these snakes prefer to avoid humans and, given the opportunity, will leave the area without biting. However, unlike other viperids they will often "freeze" instead of slithering away, and as a result many bites occur from people unknowingly stepping on or near them. This tendency to freeze likely evolved because of the extreme effectiveness of their camouflage. When lying on dead leaves or red clay they can be almost impossible to notice. They will frequently stay still even when approached closely, and will generally strike only if physical contact is made.

Feeding

Roughly 90% of its diet consists of small rodents, such as mice and voles.

Reproduction

A. contortrix breeds in late summer, but not every year: sometimes a female will produce young for several years running, then not breed at all for a time. They give birth to live young about 20 cm long: a typical litter is 4 to 7, but it can be as few as one or as many as 20. Their size apart, the young are similar to the adults, but lighter in color, and with a yellow-marked tip to the tail, which is used to lure lizards and frogs.

Venom

Although venomous, these snakes are generally non-aggressive and bites are almost never fatal. Bite symptoms include intense pain, tingling, throbbing, swelling, and severe nausea. Damage can occur to muscle and bone tissue, especially when the bite occurs in the outer extremities such as the hands and feet, areas in which there is not a large muscle mass to absorb the venom. A bite from any venomous snake should be taken very seriously and immediate medical attention sought.

In the state of Missouri about 200 people suffer from snakebite each year, mostly from this species, but there are no records of deaths resulting. Although technically the antivenin CroFab could be used to treat an envenomation from a copperhead, it is usually not administered since the risk of complications through an allergic reaction to the treatment is greater than the risk from the snakebite itself. Pain management, antibiotics, and medical supervision in the case of complications is usually the course of action.^[1]

Subspecies

See also

• List of crotaline species and subspecies
• Crotalinae by common name
• Crotalinae by taxonomic synonyms
• Snakebite

Gallery

References