Timber rattlesnake    Crotalus horridus

The timber rattlesnake has a heat-sensitive pit on each side of the head between the eye and the nostril. Hence the term 'pit viper'. Its head is flattened and much wider than the neck causing the typical viperidae triangular shaped head. The pupil of each eye is vertically elliptical, giving this snake the look of 'cat eyes'. A rattle is present at the tip of the tail. The scales are keeled (ridged). The body is gray, yellow or greenish-white with a series of dark bands along the back. A rust-colored stripe is present in the middle of the back. A dark bar may be found between the eye and jaw.

The timber rattlesnake lives in forested bluffs, abandoned sawdust piles and rock outcrops and may be found in fields in summer. This snake is diurnal until temperatures become too high in summer, it then becomes nocturnal. Much of the time is spent hiding. It hibernates in dens in rock crevices with other species of snakes.

The rattle is developed as the skin is shed. A button at the tip of the tail is present at birth. Each time the skin is shed a new segment is added to the rattle. The snake may shed its skin from three to five times in a year. Therefore, counting segments of the rattle is not a good method of aging a snake as the number of segments added each year varies and segments may be broken or lost. When disturbed, it will try to escape or coil and rattle the tip of the tail producing a buzzing noise.

Males reach maturity by age four while females reach age seven or eleven years before reproduction is possible. Mature females reproduce every 3-4 years, which means that a female may reproduce only 3 or 4 times in its entire life. The female does not eat and will stay close to her den in the last stages of gestation, venturing about to absorb heat as is needed. This time makes her an easier food source herself. Human predation is illegal.

Mating may occur in spring or fall, however, the female utilizes delayed implantation and does not give birth until late summer of early fall of the following year. Six to 14 young in are born encased in transparent membranes. Even at this tender young age of newborn, these 8-10 inch little snakelets possess not only fangs, but venom as well.

This snake injects its prey with venom then waits for it to succumb before eating it. The timber rattlesnake prefers the warm-blooded rodents and birds but will take frogs and lizards.
 

The Park's rattlesnakes were confiscated by the Illinois Department of Natural Resources and following the court cases, they were placed at the Park.