on their camouflage, and will often not strike or even rattle their tails unless physically harassed. They spend most of their lives in rocky outcroppings and talus slopes, from which they are named. Man-made road cuts are often a favorite place. They are primarily nocturnal. Most people who get bitten by the rock rattlesnake are often hiking among rocks, where it lives. If someone steps or accidentally touches it, the snake's immediate reaction is to bite. Feeding Their diets consist of small mammals, lizards, and sometimes frogs. They are often more active at colder temperatures than other rattlesnake species. Captivity Two subspecies, C. l. lepidus and C. l. klauberi, are frequently available in the exotic animal trade, and are well represented in zoos around the world. They are sought after for their wide array of potential colorations and typically docile nature. Most available are wild-caught; captive breeding, while not unheard of, is not commonplace. The two subspecies found only in Mexico are not often found in captivity outside of Mexico. Reproduction These snakes are ovoviviparous. They breed once a year, in the spring, and give birth about four months later to six to eight young. The young generally look like miniature versions of the parents and take three or more years to mature. Venom Their venom is primarily a hemotoxin, but has been known to have significant neurotoxic effects, as well. While not type-specific, the polyvalent antivenin CroFab is generally used to treat serious envenomations. Subspecies A recent review showed that the Tamualipan rock rattlesnake appears to be a separate species, Crotalus morulus References Further reading Kennicott, R. 1861. On three new forms of Rattlesnakes. Proc. Acad. Nat. Sci. Philadelphia 13: 205-208. (Caudisona lepida, p. 206.) External links Rock rattlesnake at Chihuahuan Desert Museum and Gardens. Accessed 12 December 2007. Crotalus lepidus at University of Texas. Accessed 12 December 2007. Mottled rock rattlesnake at kingsnake.com. Accessed 12 December 2007. lepidus Reptiles described in 1861 Fauna of the Chihuahuan Desert Reptiles of Mexico