The Southern Pacific Rattlesnakes range encompasses westernmost counties in southern California, the islands of Santa Cruz and Santa Catalina, and the northwestern quadrant of Mexico's Baja California. It lives in a diverse range of habitats, including, grasslands, mountain forests, coastal dunes, rocky deserts and hillsides, and agricultural fields. In the northern part of its range, it may hibernate in rocky crevices.
Like other rattlers, the Southern Pacific Rattlesnake follows a torpid existence, remaining idle some 90 percent of its life. When hungry, it takes to the hunt under the darkness of night, relying heavily on its heat-sensing organs and forked tongue and Jacobsen's organ to locate and take prey. When the weather turns cool in the fall, the snake enters hibernation.
Emerging from hibernation in the spring, the Southern Pacific Rattlesnake begins its breeding season, which may last for a couple of months. Two males may perform "combat dances" to win the right to mate with a female, who releases chemicals called "pheromones" to signal her receptivity. The triumphant male rubs her with his chin and touches her with his tongue in an elaborate courtship prior to mating.
Unlike some other species, which may lay eggs, the female Southern Pacific Rattlesnake delivers eight or ten live young about three months after mating. The young, each six to ten inches in length, are born with fangs, with each newborn ready to defend itself and hunt prey. Young snakes leave the mother in short order, becoming independent, though they may follow the mother's scent to a wintering den that may be used for many generations. In the wild, the snake may live for one or two decades.
It eats small mammals, birds, reptiles and amphibians.