Vipers and Pitvipers: Viperidae

The defense behaviors of the vipers and pitvipers are perhaps their best-known feature. The snakes coil up into a flat spiral with the head curved up from the middle of the coil. Some also hiss, jerk forward with the head, rattle the tail, or blow up the body, which makes the snake look larger. Each of the behaviors may be enough to scare off a predator. Many of the warmer climate species remain active all year long, but the temperate species may hibernate for many weeks. Those living high up in the mountains and other places with especially cold winters typically hibernate for several, sometimes up to eight, months a year.

Males mate every year in the spring or fall, sometimes wrestling with other males over the chance to mate with a female. Females, especially those in colder climates, often skip a year or more between matings. The females of most species produce eggs, but these hatch inside her body so that she gives birth to baby snakes. A few species, such as the night adders, lay eggs instead. Recent research suggests that some mothers may linger around the young for a few days, possibly providing some protection against predators that may hunt them for food.