Natural History:
This shy species is found in rugged terrain along heavily vegetated, rocky outcrops on partially forested hillsides. It is active from April to October and prefers air temperatures of 80-90°F.
The Timber Rattlesnake is diurnal during spring and fall but prowls at night during the summer months to avoid the higher daytime temperatures. Although this snake may travel over 30 yards a day to seek areas with abundant food, it frequently spends long periods coiled and immobile, patiently waiting for prey to approach. Females apparently wander less than males; furthermore, they generally do not feed during pregnancy, relying on stored fat to maintain themselves until the birth of the young. However, Rick Strawn (pers. comm., 1991; Collins, 1993) maintained a captive gravid female from Johnson County that was fed regularly until two weeks prior to giving birth. During winter, this snake retreats deep into the burrows and crevices of rocky outcrops to avoid cold weather.
Timber Rattlesnakes mate during the spring, soon after emergence from winter inactivity. Courtship is poorly documented, but involves the male positioning himself alongside the female and stimulating her with quick, rapid jerks of his head and body. The male curls his tail beneath the female's until their cloacal openings meet and copulation occurs.
Females may produce litters only every other year. The young are born in August, September, or October, and litters range from five to fourteen (Fitch, 1985), with an average of eight or nine. Collins (1982) reported a female from Johnson County giving birth to six young on 23 September. Young Timber Rattlesnakes are venomous at birth and have a single button on their tail. Additional segments are added each time a snake sheds its skin, producing a rattle that may have up to fifteen segments. Females normally reach maturity in their fourth year (Fitch, 1985). Species of Crotalus are viviparous and form well-vascularized chorioallantoic placentae, primarily functioning in gas exchange and fluid/ion regulation. Embryonic development is largely lecithotrophic, with yolk providing most of the organic energy. Available physiological and comparative data indicate limited but functional maternal nutrient transfer; overall, Crotalus represents predominantly lecithotrophic viviparity with modest placental contribution.
This species feeds on mice, rats, squirrels, rabbits, bats, and other small mammals, as well as on smaller snakes (Collins, 1993).