Crotalus stephensi - Panamint Rattlesnake

Venomous

The venom of this snake is potentially dangerous to humans.

Size

Adults are 23-52 inches in length (58-132 cm) averaging 2 - 3 feet. Young 10 inches.

Appearance

A heavy-bodied, venomous pit viper, with a thin neck and a large triangular head. Pupils are elliptical. Scales are keeled.

Shows a great variety of body coloration which usually allows the snake to blend into its environment - tan, yellowish, orangish, gray, off-white, brown. The body is marked with a pattern consisting of dark speckled banded markings, which can be vague or distinct. A dark band or bands on the tail, but not usually alternating with light bands.The ground color of the tail is generally the same as the body color, not contrasting sharply with it. The last dark tail bands often seem to fuse together into one large black band just before the rattle. Compare with C. m. pyrrhus. The tail has a rattle on the end consisting of loose interlocking segments. A new rattle segment is added each time the skin is shed. Newborn snakes do not have a rattle - just a single button which does not make a sound.

Heat sensing pits on the sides of the head help the snake to locate prey by their warmth. Long, hollow, movable fangs connected to venom glands inject a very toxic venom which quickly immobilize prey. The snake can control the amount of venom injected and the fangs are replaced if broken. Bites on humans are potentially dangerous without immediate medical treatment. Even a dead snake can bite and inject venom if the jaws reflexively open when they are touched.

Behavior

Primarily nocturnal and crepuscular during periods of excessive daytime heat, but also active during daylight when the temperature is more moderate. Not active during cooler periods in Winter.

An ambush hunter, it may wait near lizard or rodent trails, striking at and releasing passing prey. The snake then follows the trail of the envenomated animal and swallows it whole. Prey is also found while the snake is actively moving.

When alarmed, a rattlesnake shakes its tail back and forth. The movement rubs the rattle segments together producing a buzzing sound which serves as a warning. Juveniles are born with only a silent button at the end of the tail.

Diet

Eats small mammals, lizards, and birds.

Reproduction

Live-bearing; young born July and August.

Range

Found in central eastern California, from approximately the Mojave River north along the east side of the Sierras into Nevada. Sea level to 8,000 ft. (2,440 m).

"Klauber (1930, 1936) suggested that C. m. stephensi formed a zone of intergradation with C. m. pyrrhus in the Mohave Desert (i.e., the Barstow–Ivanpah–Hoover Dam line). His primary evidence was the presence of an incomplete separation of the prenasal and rostral scales in some individuals he examined from this region. This condition, however, occurs infrequently throughout the distribution of C. mitchellii (Klauber, 1936, 1949, 1963), and hence its utility as a robust morphological indicator of intergradation between C. m. stephensi and C. m. pyhrrus is unresolved."

Habitat

Associated mostly with habitats composed of rocky outcrops and boulders, but also found in creosote bush and cactus deserts and open coniferous woodlands.

Taxonomic Notes

In a 2007 paper, * using molecular data, Douglas et al showed that this snake is a distinct species, not a subspecies of Crotalus mitchellii.