Crotalus mitchellii pyrrhus - Southwestern Speckled 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 - 3.5 feet. Young 8.5 - 10.5 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, from off-white, yellowish, gray, tan, pinkish, pale orange, to brown. Snakes from dark lava bed environments can be almost all black. The body is marked with a vague pattern consisting of dark speckled banded markings. Dark and light rings surround a thick tail. The tail rings are in considerable color contrast with the body color, with the terminal rings being black and with an ash-gray ground color on the tail often present. Compare with C. stephensi. 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

This subspecies, Crotalus mitchellii pyrrhus - Southwestern Speckled Rattlesnake, is found throughout much of southern California north to aproximately the Mojave river, east into Nevada and extreme southwest Utah, south into Arizona and southern Baja California Norte.

The species Crotalus mitchellii continues south to the cape region of Baja California, Mexico.

From sea level to 8,000 ft. (2,440 m).

Habitat

Associated mostly with arid areas strewn with rocks and boulders - alongside buttes, mesas, and desert outcroppings, but sometimes found on loose soil. Occurs in areas vegetated by sagebrush, creosote, thornscrub, chaparral, pinon-juniper woodland, succulent desert.

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.