Timber Rattlesnake (Crotalus horridus)

For information on Wisconsin's snakes including an identification key and more, order your copy of Snakes of Wisconsin.

Description

The timber rattlesnake is a heavy-bodied snake with a broad head that is distinct from its narrow neck. The top of the head is unmarked and usually yellow to light gold in color. Adult timber rattlers average 35 to 50 inches in total length. They have a yellow, brown, rust-orange, or in rare cases gray ground color with black or dark brown crossbands extending along the back. There is a dark brown stripe behind each eye, and there may be a rust-colored middorsal stripe from the neck to the tail. The tail is short and thick, all black, and tipped with a tan rattle. Juvenile timber rattlers are marked like the adults.

Distribution

This species occurs from southern New Hampshire and southern Ontario to northern Georgia, and west to southeastern Minnesota through northeastern Texas. In Wisconsin, timber rattlers are found in the southwestern corner of the state, and north along the Mississippi River corridor into Pierce County.

The range of this species has changed little since historical times. However, within their current range, their distribution has become very patchy and fragmented. In fact, this species is considered rare to imperiled in fifteen and in Ontario, and is extirpated from two states.

Habitat

Timber rattlesnakes can typically be found in bluff prairies and oak woodlands in relatively remote areas. They prefer rocky outcrops and open grassy areas with southerly exposures in the spring and fall. During the summer, they inhabit deciduous forests and open valleys. Rock fissures and crevices provide communal dens for overwintering.

Life History

Habits

Timber rattlers begin emerging from hibernation in April to early May, depending on temperatures, to take advantage of the warm spring sun. They will remain close to the den site until temperatures become consistently warm and then they venture out into the surrounding landscape. Pregnant females will usually remain around denning sites, basking in the sun to speed the development of there young. Males, non-gravid females and immature rattlesnakes will return to the den site in early fall and remain active into October. They are both diurnal (active during the day) and nocturnal (active after dark) in the summer, but only diurnal in the spring and fall.

Timber rattlesnakes are experts at climbing along rocky ledges and scaling steep bluffs, and are also able to swim. Rattlesnakes typically crawl with the tip of their tail and rattle held perpendicular to the ground.

Breeding

Timber rattlesnakes breed near the denning site before moving into the woods for the summer. Females generally reproduce only every third to fourth year. Female timber rattlers are believed to have infrequent reproductive events due to the fact that they rarely feed during pregnancy, and their body stores are severely depleted during the years when they breed. Being very slow to mature, they first reproduce at 7-11 years of age, and reproduce only 3-5 times during their life. In Wisconsin, litters of 6-15 young are born from late August to mid-September. Juveniles experience high mortality rates due to their small size, which makes them vulnerable to a variety of predators.

Food Habits

Timber rattlesnakes feed primarily on small mammals which include mice, voles, chipmunks, squirrels, and young rabbits. They are primarily sedentary feeders, preferring to wait for prey to come to them. They often coil alongside fallen logs (natural travel corridors for small mammals) and wait for prey to come into range. The snake's heat-sensing pits, located between the eye and the nostril on each side of the face, direct the attack; the effect of the venom allows the rodent to run only a short distance before dying. The snake follows the scent of the venom to the prey item and then swallows it whole. The venom, composed of enzymes, also helps with the digestive process.

Other Behaviors

Timber rattlesnakes are not a major threat to humans and livestock. This snake has a secretive nature and prefers those areas that are mostly unused by humans. Timber rattlers prefer to remain quiet, relying on their cryptic coloration to go unnoticed. They often are reluctant to rattle, preferring not to call attention to themselves. This rattlesnake is notably docile unless provoked or unless going through a molting cycle, which impairs their vision. They can be defensive if disturbed and will bite.

Predators

Humans are the dominant predators of adult timber rattlesnakes, although raptors, turkeys, badgers, skunks and raccoons also prey on them.

Facts About Rattlesnake Bites

Death due to a rattlesnake bite is unlikely; only one rattlesnake bite fatality has been documented in Wisconsin since 1900. Timber rattlesnake bites in Wisconsin have averaged one every four years in recent history (1982- 1997). Five additional bites have occurred as the result of intentional handling of rattlesnakes, with 80% of these involving the abuse of alcohol. Rattlesnakes can control the injection of venom when biting; up to 60% of all poisonous snake bites to humans are "dry," containing no venom.

Impacts Of The Bounty

A bounty (a fee paid to people to kill pest species) of up to $5 a tail was once offered for rattlesnakes in Wisconsin. Although habitat loss and commercial and sport hunting continues to contribute to population declines, the total loss of snakes harvested for bounties had a tremendous impact. Populations of the rattlesnakes declined precipitously during the years a bounty was offered. Since timber rattlesnakes typically use the same denning sites year after year, locating them was quite easy. Pregnant female timber rattlesnakes require open warm basking sites to allow for normal development of the embryo, making them especially vulnerable to harvesters and collectors. Bounty hunters would primarily collect the snakes in the early spring, August, and late fall, when they were most concentrated. Bounty hunters depleted many of the dens. One bounty hunter boasts of killing 5,700 timber rattlesnakes in a single season!

The rattlesnake bounty ended in 1975 in Wisconsin, due primarily to the declining populations of the snake. In fact, the other species of rattlesnake in Wisconsin, the massasauga (or swamp rattler), was placed on the endangered species list that same year. Until that time, it was thought that human intervention was necessary to keep the rattlesnake population low. It now appears that natural predation and environmental conditions are sufficient in keeping populations in check.

Current Status

The timber rattlesnake was listed as a "Protected Wild Animal" in 1998. This designation makes it illegal to take or kill this species except under the following conditions: A timber rattlesnake may be killed in an immediate life-threatening situation involving human life or domestic animals. This species or its parts may not be possessed. See NR 10.02 [exit DNR] for more information.

This snake is also listed as a "Species of Special Concern" because of its low numbers. There is sentiment that current population trends warrant a federal listing. The timber rattlesnake is listed as a threatened species in Illinois and Minnesota. Concern about the potential threat this species poses has prevented Wisconsin from providing greater protection thus far.

Existing Threats

Increased residential development within the blufflands of southwestern Wisconsin has led to increased human/timber rattlesnake encounters, resulting in the loss of snakes and their habitats. The collection of timber rattlesnakes for hides (used for hat bands, belts, and boots), meat, venom, and artifacts (rattles and freeze dried snake heads) has continued to deplete already threatened populations up through 1997.

Conservation And Management

In order for the timber rattlesnake to be further protected, information must be provided to the public to destroy the myths surrounding this species. An education program to help conserve, manage and protect this species is being developed. This program is primarily for private landowners within timber rattlesnake range, but includes education beneficial to teachers and students, naturalists, public land stewards, and resource managers. Included in this program are training workshops and educational material to aid in the identification of snake species, descriptions of their life histories, safe alternatives to killing snakes, and information on land management to restore native bluff prairie habitat.

Given their slow rate of reproduction, high mortality rates, and the late age of maturity, recovery of this species will require decades. However, it is uncertain whether recovery is even a possibility given current population levels in the state.

What You Can Do

If you should come across a timber rattlesnake, please do not try to capture or disturb it. Admire the snake from a distance only. Remember, they are not aggressive. They will usually hide or keep quiet while you go by. Most individuals are reluctant to rattle unless they are in a shedding cycle where their vision is impaired. Report any sightings of timber rattlesnakes to the DNR by calling toll free 1-888-74SNAKE (1-888-747-6253). This will help us track the species range and help identify new areas where they may occur. Call this number if you have a rattlesnake you want relocated or to report the killing of a specimen.

Staying on the trail and wearing hiking boots can greatly reduce your chances of being bitten by a rattlesnake. If you are bitten, having knowledge of first aid and staying calm can lessen the effects of the bite. Medical treatment should be received within one or two hours.

Rattlesnake Bites

Timber rattlesnakes are generally very docile snakes, unless harassed. They prefer not to strike, but instead rely on cryptic coloration to remain hidden. This venomous species can inflict a serious bite, and people are urged to walk away from them when encountered. Records show that there is a greater risk of being bitten if an attempt is made to kill them. If you are bitten, remain calm and seek medical attention as soon as possible (preferably within one hour). Please contact the Poison Control Center in Madison also at 1-800-815-8855, and let them know what hospital you are going to for assistance.

Rattlesnake Removal

If you find a rattlesnake on your property and want it removed alive, please carefully capture or contain it. Keep in mind that rattlesnakes can only strike up to one-half of their body length. Either cover the snake with a bucket or trash can or use a potato rake or other long-handled tool to gently lift and place it in a tall container. Cover with a lid and weigh it down to prevent escape. Store the container in full shade when possible. Call the toll free rattlesnake hotline at 1-888-747-6253. Please follow the instructions on the recorded message. Someone will get back to you as soon as possible. Removed specimens will be marked and released at protected sites.

Conservation

You are encouraged to use the hotline to report other information about timber rattlesnakes, including sightings, den locations, mortalities and illegal collecting or killing. Your cooperation will help us better track this species. We also ask that you use the hotline to report sightings of three other declining snake species, the black rat snake, blue racer, and the bullsnake. These snakes are declining because of habitat loss and the overgrowth of bluff prairies.

Call also to receive information about bluff prairie habitat management and restoration.

This Rattlesnake Hotline segment is also available as a handy pocket card. Please order by emailing Bureau.EndangeredResources@wisconsin.gov.

See Also:
Living with Snakes
Avoiding and Treating Timber Rattlesnake Bites

Information compiled from publication ER-531 98REV.

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