They have an unmarked copper-colored head and reddish-brown, coppery bodies with chestnut brown cross bands that constrict towards the midline. Copperheads are thick-bodied and have keeled scales. They have a temperature sensitive pit organ on each side of the head between the eye and the nostril. Sometimes when touched, they emit a musk that smells like cucumbers.
The average length of adult copperheads is 30 inches (76 centimeters). Males have longer tails then females, and females grow to greater lengths.
Copperheads have grooved fangs that can be 0.3 inches (7.2 millimeters) in length. The length of the snake relates to the length of the fangs; the longer the snake, the longer the fangs.
Northern copperheads live in the United States from the Florida panhandle, north to Massachusetts and west to Nebraska. Of the five different subspecies, the northern copperhead has the largest range. It inhabits northern Georgia and Alabama north to Massachusetts and west to Illinois.
Copperheads prefer terrestrial to semi-aquatic habitats, which include rocky-forested hillsides and various wetlands. They have also been known to occupy abandoned and rotting wood or sawdust piles.
The copperhead is a carnivore, as an adult eating mostly mice but also small birds, lizards, small snakes, amphibians and insects‐especially cicadas. Copperheads have fangs that inject its prey with venom that causes red blood cells to break down. Thus subdued, the prey is easy for the snake to swallow whole.
The copperhead seeks out its prey using its heat-sensitive pits to detect objects that are warmer than its environment. The pits also enable them to find nocturnal mammalian prey. Adult copperheads are primarily ambushers. When attacking large prey, the copperhead bites then releases immediately to allow the venom to take its effect; then later the snake tracks its prey. Smaller prey is usually held in its mouth until it dies.
The copperhead is the cause of many snakebites yearly but they are rarely fatal. Bites occur by accidentally stepping on or touching the snake, which tends to be well camouflaged with its surroundings. When touched, the copperhead quickly strikes or remains quiet and tries to crawl away. Sometimes when touched, they emit a musk that smells like cucumbers.
Young copperheads eat mostly insects, especially caterpillars, and use their yellow tipped tails to function as a worm-like lure to attract prey.
The copperhead at the Smithsonian's National Zoo eats mice and rats.
Both sexes reach sexual maturity at four years when they are about two feet in length. The breeding season is from February to May and from August to October. Males seek out sexually active females using their tongue to detect pheromones in the air. Once he has located a female, the male will begin moving his head or rubbing his chin on the ground. Eventually, after courtship, the male aligns his body with hers. This courtship may last for an hour or more if the female does not respond. After being sufficiently stimulated, the female lifts and arches her tail and lowers the scale that covers her cloaca. Then the male arches his body and tail, everting one of his two hemipenes and mates with the female. Mating time varies; the range can be as much as 3.5 to 8.5 hours. The long mating time could correlate with the fact that females usually only mate with one male per year. During the mating period, males produce a pheromone that makes the female unattractive to other males who pay little or no attention to mating or just mated females. Females also have little interest in mating after a long, successful first mating.
A female who breeds in autumn can store the sperm until after she emerges from a hibernating site. The length of time that the sperm can be stored appears to differ depending on where it is being stored. If the sperm is stored in the cloaca, it lasts a relatively short time, whereas if it is stored in the upper end of the oviducts in vascular tissues specialized as seminal receptacles, it seems to last much longer. Copperheads have a gestation period of three to nine months. They are a live-bearing snake, typically producing two to ten young. Larger females produce larger broods. After birth, the female provides no direct care for the young.
They produce large, yolk-filled eggs and store the eggs in the reproductive tract for development. When carrying young, some females will not eat at all because the embryos occupy so much of the body cavity. The embryo, during this time, receives no nourishment from the female, only from the yolk. The young are expelled in a membranous sac and weigh less than an ounce (28 grams).
Young copperheads are 7 to 10 inches (18 to 25 centimeters) long and grayer in color than adults. They have a sulfur yellow tipped tail, which fades with age and is lost by age 3 or 4.
Even newborn copperheads have fully functional fangs capable of injecting venom. These newborns have venom that is just as toxic as adults' venom. The fangs are replaced periodically with each snake having a series of five to seven replacement fangs in the gums behind and above the current functional fang.
They are most active April through late October; diurnal in the spring and fall, and nocturnal during the summer.
The life span of the copperhead is around 18 years.
Globally, copperheads are a species of least concern, but they are listed as endangered in the state of Massachusetts.