Description: Small pit viper occurs in a variety of background colors ranging from pale gray to bluish gray, some shade of brown or tan, or even pinkish. Dorsal pattern consists of widely separated narrow, dark, serrated crossbands. Has mottling throughout. Adults are usually less than two feet but have been measured as long as 30.5 inches These small rattlesnakes are highly variable in pattern and coloration, usually gray with dark bands but may range from tan to pinkish. Infants have a bright orange or yellow tail tip, which they likely use for caudal luring (swinging the tail as bait to attract prey).

Habitat: This snake occurs mainly in rocky mountainous areas, including talus slopes, gorges, rimrock, limestone outcrops, and rocky streambeds, often in arid or semi-arid areas vegetated with pine-oak, oak-juniper, pinyon pine, ponderosa pine, or agave; it also inhabits mesquite grasslands and rocky desert flats and canyons, as well as mixed boreal-tropical forest and tropical deciduous forest in Mexico. In forests it tends to occupy open sunny areas. It is a terrestrial species that may sometimes climb into low vegetation. It takes refuge under or among rocks, in animal burrows, or in or under stumps or similar refuges.

Range: USA (SE New Mexico, SW Texas), NE Mexico (Chihuahua, Coahuila); Type locality: Presidio del Norte and Eagle Pass, Texas.

Found in these States: NM | TX

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.

Diet: Their diets consist of small mammals, lizards, and sometimes frogs. They are often more active at colder temperatures than other rattlesnake species.

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.

Status: Listed as Least Concern in view of its wide distribution, presumed large population, and because it is unlikely to be declining fast enough to qualify for listing in a more threatened category.

Taxonomy: