Overview

Timber Rattlesnakes (Crotalus horridus) are found primarily in temperate forests throughout the eastern United States. They range from northern Florida to eastern Texas north to Wisconsin and New Hampshire but are absent from Michigan. Historically their range included southeastern Ontario and southern Maine but populations there are believed to have been extirpated. While the coastal canebrake form of the Timber Rattlesnake can be quite common in the southeastern United States, Timber Rattlesnakes are generally considered uncommon or rare through most of the species range. The physical coloration of the Timber Rattlesnake is quite variable throughout the species' range however the basic pattern, dark W-shaped bands across the body on a lighter background, is fairly consistent. The background color varies from yellow to brown to gray and gets darker closer to the tail. The tail itself is usually black and some individuals are almost entirely that color. In more northern populations individuals tend to be darker and are most often yellow or black. Timber Rattlesnakes are a large and robust snake, with males typically reaching lengths of up to 1.32 meters and females up to 1.09 meters. The species was described by Linnaeus in 1758 and currently no subspecies are recognized. The genus, Crotalus, literally means “hollow in the rocks”, after the denning habitat that this species uses.

Habitat

Populations of Timber Rattlesnakes throughout the Appalachian Mountains and connecting ranges to the northeast can only persist where suitable denning habitat is available. Denning areas are typically rocky and are either made up of crevices at the bottom of cliffs or talus slopes below cliffs. In most places den sites are situated on south or west-facing slopes where temperatures tend to be higher. Home ranges and movement vary greatly among Timber Rattlesnakes depending on sex, age, and reproductive state. Males and non-gestating females move between 1.6 to 4 km from the dens each year, with larger individuals and males moving greater distances. Gestating females move to birthing sites either at the dens or on top of the ridges near to them and will remain under and near chosen features, commonly referred to as birthing rocks, through the summer until birthing occurs sometime in August to September. Because of short active periods and the high costs of reproduction, females reproduce every three to four years in northern populations with females occasionally reproducing every two years farther south. Between 4 and 14 young are usually produced by females during reproductive years with larger females being the most fecund. Timber Rattlesnakes have specialized heat-sensing pits on the front of their heads that allow them to find warm-blooded prey such as mammals. Rodents including mice, chipmunks, and voles make up a major portion of the Timber Rattlesnake's diet. Habitat fragmentation by roads has resulted in many snakes being killed by traffic, often intentionally. Persecution by humans is a major threat to the species and until the 1970s, many northeastern states paid a bounty for any killed rattlesnake. In most of these states the species is now protected.

For more information, download the Timber Rattlesnake Fact Sheet