Copperheads freeze because camouflage beats flight
The eastern copperhead (Agkistrodon contortrix) is a heavy-bodied pit viper of the eastern United States, banded with dark hourglasses on a reddish-brown ground. Rather than slither away, it tends to freeze and trust its camouflage—which is why its bites make up half of all treated snakebites in the country.
The scientific name describes the animal. Agkistrodon joins Greek words for fishhook and tooth, and contortrix comes from the Latin for twisted or intricate, usually taken to mean the bands that are wide along the flanks but pinched to narrow hourglasses along the spine. Newborns sport green or yellow tail tips that darken to brown or black within a year. Adults usually measure 50 to 95 centimetres, males topping out near 76 and females near 66, and the head is broad, with a snout sloping back more than a cottonmouth's.
Its range covers much of the eastern and central United States, from Texas and Nebraska to Florida and Massachusetts, plus Chihuahua and Coahuila in Mexico. It favours deciduous and mixed woodland but also turns up on rocky ledges and in swampy lowlands. In winter it hibernates in dens or limestone crevices, often alongside timber rattlesnakes and black rat snakes. Unlike some other pit vipers, it has mostly failed to recolonise land north of the last Ice Age's terminal moraine, though it does reach southeastern New York and southern New England.
It hunts by ambush, settling into a likely spot and waiting for arthropods and small vertebrates to wander past. Because it is common and sits tight when approached, people are bitten after unknowingly stepping on or beside one. Kingsnakes have long been major predators, and rising copperhead numbers in some areas have been linked to falling kingsnake populations.
Colour varies: specimens from Texas, Alabama and Louisiana have shown bands fused into stripes. Five subspecies were once recognised, but recent genetic work has reshaped that picture.
Source: Eastern copperhead
