Timber Rattlesnake, Crotalus horridus

Timber Rattlesnake, Crotalus horridus

While it’s hard not to let out a squeal when you stumble upon one, Timber Rattlesnakes are more afraid of us than we are of them. They are unlikely to strike unless provoked.
Read more: Wisconsin Native Snakes


There are benefits from Timber Rattlesnakes. They are seemingly a natural pest control. The Timber Rattlesnake feeds on small to medium-sized rodents, such as mice, shrews, chipmunks and squirrels.

Timber Rattlesnake
Crotalus horridus
Lifespan: Average 10 to 20 years, but up to
30 years
Weight: 1.1 to 3.3 pounds
Average Size: 3 to 5 feet
Color: It comes in two color phases, yellow and dark.
Sexual Maturity: 4 to 11 years, males mature earlier than females
Mating Style: Polygynous
Gestation: Average 90 days, but may be up to 5 months
Number of Young: 6-10 snakelets
Diet: Primarily eat small to medium-sized rodents, such as mice, shrews, chipmunks and squirrels.


Adult timber rattlesnakes range from 36-60 inches in length, and the record length for the species is 74.5 inches. They exhibit sexual dimorphism as the males are larger, weighing around 2.0 lb. while the females weigh on an average 1.3 lb.

Timber Rattlesnakes have several color morphs. The background color of the black morph is gray and the patterns are a rich, velvety black. The background color of the yellow morph is tan, the patterns are a sulfur yellow tinged brownish in patches. All the snakes have transverse bands of color.

The timber rattlesnake’s most distinguishing characteristic is its rattle. The rattle is composed of interlocking segments of dry, horny, keratinized skin that are not lost during shedding. When frightened, rattlesnakes vibrate their tails making a buzzing sound. This acts as a warning signal to predators.


In the northern parts of their range, timber rattlesnakes live in forested rocky hills. Crevices in rocky cliffs usually facing south or large boulders piled together make up the hibernating dens.


In the warmer months, timber rattlesnakes are lone predators. During the summer, the snakes are migratory. They roam several miles from their winter den and do not have a permanent home. They cannot tolerate winter and hibernate for up to 7 months each year, returning to the same den each year. They hibernate in dens which are often in rock crevices. These dens may accommodate 15-60 snakes.

The attack stance of rattlers is well-known. The snakes rise vertically with their head and neck forming an "S", and when ready they thrust with fangs exposed. Another common behavior of rattlers is ritualized fighting among the males. It often occurs in the periods just before mating season. They lift their bodies and wrap themselves around each other, moving back and forth in a swaying motion, trying to pin each other down.

  Timber Rattlesnake Bites

If cornered and provoked, a timber rattlesnake may respond aggressively. It will usually rattle its tail to let you know it is getting agitated. The snake may even puff itself up to appear bigger. Upon further provocation, the snake may bluff strike, where it lunges out, but doesn’t open its mouth or it may strike with an open mouth.

Because venom is costly for a rattlesnake to produce, and you are not considered food, a snake often will not actively inject venom when it bites. In fact, nearly half of all timber rattlesnake bites to humans contain little to no venom, commonly referred to as dry or medically insignificant bites.

Death due to a rattlesnake bite is unlikely. Timber rattlesnake bites in Wisconsin are rare. Most bites result from people intentionally handling rattlesnakes and often involve the use of alcohol or drugs.

  Communication and Perception

Like the other snakes in the family Viperidae, Timber Rattlesnakes are pit vipers. This means they have heat sensitive pit organs located between the nostrils and the eyes. They are sensitive to radiant energy and can distinguish very slight changes in temperature.



Males follow scent trails to find reproductively active females. Once a male finds a receptive female, he rubs the female's neck with his chin and places his body along hers. The male then rapidly jerks his head and body until he can move his cloaca under hers and insert his hemipenis. Copulation may last for several hours. Males may fight for access to a receptive female.


Most mating occurs in the summer months, from mid-July to October. Females store sperm through the winter for use in the spring when they emerge from hibernation. Females begin the formation of eggs and yolk in the late summer and fall, those eggs then ovulate the following spring.

Birth of Snakelets

The live young are born in the autumn, from August through October. Timber rattlesnakes are ovoviviparous, meaning that the eggs are incubated and hatched within the female and she gives birth to live, precocial young. Females give birth to 1 to 20 young, usually 6 to 10.

Litter size depends on the size of the female, with larger females having more young. The young have similar patterns to adults, but tend to have a grayish hue. They have their first shedding at 7 to 10 days old, at which point they expose a button-like terminal scale where their rattle will eventually grow.

Even newborn young are dangerous, with fangs from 2.6 to 3.8 mm long and a supply of venom.
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