Reproduction Crotalus atrox reaches sexual maturity at 3 years. Mating occurs in the spring following emergence from hibernation. Females are passive during courtship, while the male crawls in jerks on top of the female, all the while flicking his tongue. Vigorously jerking the hind portion of his body, he presses his tail beneath that of his partner, who in turn lifts her tail. Their cloacas make contact, and the male then inserts his hemipenis, which is deeply forked.
Copulation lasts for hours, with several interspersed resting periods.
The gestation period lasts for 167 days. The birthing process may last for 3 to 5 hours and produce 10 to 20 young. The young only stay with the mother for a couple of hours, for a day at the most. Then they scatter in search for food and potential winter refuge. Behavior Western Diamondback Rattlesnakes are aggressive and easily excitable.