Species Description
The Eastern Copperhead (Agkistrodon contortrix) is a heavy-bodied, venomous snake with a pale tan, pinkish-tan, light brown, or gray body with a series of 10–18 crossbands that become narrower along the midline of the back. These bands resemble hourglasses or bowties, but may not always meet at the middle, resulting in an alternating pattern on each side of the body. A series of dark brown spots may also be present on the flanks between the crossbands. The head is coppery brown on top, and the dorsal scales of the body are keeled. There is a heat-sensing pit located between the eye and the nostrils, and a narrow, faint dark stripe behind each eye. Juveniles are colored and patterned similarly to adults, with the notable exception that the tip of the tail is a greenish-yellow color.
Adults typically measure 50–95 cm (20–37 in.) in total length but may reach a maximum length of around 132 cm (52 in.). They are sexually dimorphic in size, with males usually growing larger than females.
Eastern Copperheads rely heavily on their extremely effective camouflage to avoid detection. When approached, these snakes often remain motionless, rendering them almost imperceptible among leaf litter. When disturbed, copperheads will frequently vibrate their tails and may strike in self-defense if not given space to retreat.
Taxonomy
Copperheads were long considered to be a single species with up to five different subspecies. However, recent genetic analysis and niche modeling have recommended that two independent species of copperhead be recognized: Eastern (A. contortrix) and Broad-banded (A. laticinctus).
The genus name Agkistrodon is derived from the Greek words ankistron, meaning “fishhook,” and odon, meaning “tooth.” This is likely a reference to the fangs of the snakes in this genus. The specific epithet is derived from the Latin word contortus (twisted or contorted), which is typically interpreted as a reference to the irregular, distorted pattern of darker bands across the snake’s back.
Distribution
The Eastern Copperhead is found throughout much of eastern North America. Its range extends from southern New England to northern Florida and west through the southern Great Lakes states and southern Iowa to southeastern Nebraska, eastern Kansas, central Oklahoma, and eastern Texas.
Habitat
Eastern Copperheads are mainly terrestrial snakes but inhabit a wide array of habitats. In much of North America, they favor deciduous forests or mixed woodlands, where they are often associated with outcrops, bluffs, or other rocky features. In the southernmost portion of their range, they can be found in pinewoods, floodplains, swamp edges, and hardwood hammocks. They can also be found in close proximity to human habitation, such as farms and neighborhoods, particularly those adjacent to forested habitat. Copperheads will readily use abandoned structures, rock walls, wood piles, and similar forms of cover when available in anthropogenic areas.
Movement and Home Range
Eastern Copperhead movement and home ranges may vary significantly depending on geographic location, sex, age, and reproductive state. Copperhead home ranges are much smaller than those of many other North American vipers, with some estimates in Alabama being 17.8 ha for males and 7.1 ha for gravid females (Sutton et al. 2017). Adult males generally have larger home ranges and move more extensively than females, likely due to behavior associated with courtship and reproduction. Copperheads show high site fidelity, often returning to the same hibernacula, gestation sites, and foraging sites year after year.
Eastern Copperheads are primarily crepuscular and nocturnal throughout much of the year but may become more active during daylight hours in cooler spring and fall weather. In the winter, copperheads often hibernate in large, rocky communal dens with other snake species. However, in the southern portion of their range, they frequently hibernate individually in smaller refugia such as hollow stump holes.
Diet
Eastern Copperheads eat a variety of prey items, including small mammals, birds, frogs, salamanders, small turtles, snakes, lizards, caterpillars, millipedes, and cicadas. Like most pit vipers, the Eastern Copperhead primarily hunts as an ambush predator, positioning itself in strategic locations and waiting for prey to come within striking distance. However, copperheads may actively hunt some prey, such as newly emerged cicadas, which they often pursue into shrubs and small trees. Juvenile copperheads use a hunting strategy known as caudal luring, where they wiggle their yellow-tipped tails, which resemble a caterpillar or worm, to lure hungry frogs and lizards into striking range. Small prey items are often held until dead, while larger prey is usually released after envenomation and tracked down after succumbing to the venom.
Reproduction
Eastern Copperheads typically breed in the late summer and early fall; however, spring courtship and mating do occur. Mating is sometimes preceded by male combat, in which two males raise the front halves of their bodies, entwine, and attempt to push their opponent to the ground. Like many North American pit vipers, female Eastern Copperheads have the ability to store sperm from fall matings until ovulation occurs in spring. Gravid females will often congregate in small groups at exposed rock crevices, logs, or other suitable gestation sites until they give birth between July and October. A litter from a single snake can range from 1 to 21 (typically 4 to 7), and neonates measure about 20 cm (8 in.) in total length.
Conservation Concerns
Habitat loss, degradation, and fragmentation may affect local copperhead populations throughout their range. Road mortality, human persecution, and disease may also have significant effects. Eastern Copperheads are listed as “Least Concern” on the IUCN Red List of Threatened Species due to their broad distribution, relative abundance, and the low likelihood of significant widespread declines. While the overall risk to the species is low, there is concern for populations at some of the northern edges of their distribution, where they are listed as “Endangered” in both Massachusetts and Iowa and as a “Species of Conservation Concern” in New Jersey.
Although venomous, bites from Eastern Copperheads are rarely fatal. A bite from any venomous snake should be taken seriously, and immediate medical attention should be sought, as there is always a risk of allergic reactions or secondary infections.
Interestingly, the venom of the Southern Copperhead has been found to contain the protein contortrostatin, which has been shown in animal studies to inhibit the growth of cancer cells in mice and prevent tumors from spreading to other areas. However, these findings are based on animal models, and further research is needed to confirm its safety and effectiveness in humans.