Western Rattlesnake

(Crotalus viridis)

"Prairie Rattlesnake"

"Arizona Black Rattlesnake"

Color Photographs: U.S. Fish and Wildlife Service

"Northern Pacific Rattlesnake"

Color Photograph: © Corel Corp.

"Southern Pacific Rattlesnake"

Color Photograph: Chris Brown, U.S. Geological Survey

"Great Basin Rattlesnake"

Color Photograph: U.S. National Park Service

The three (and a partial fourth) internasals in red touching the rostral scale (in blue). The tongue is naturally blue.

Color Photograph: Courtesy of Jack Goldfarb

Western Rattlesnake (Crotalus viridis) (see note below)

Identification: Length 16 to 65 inches. The back is marked with a series of ovate dark blotches interspersed with the lighter ground color. Blotches becoming bands toward the tail of the snake. Tail of snake with weak bands and with a very wide terminal black to brown band just before the tail. Head with a dark band strongly accented with light bands above and below it stretching from rear margin of the eye to the base of the jaw. The only rattlesnake species in western North America with 3 or more internasal scales touching the rostral scale [Note: If you can see this character in the field, you are way to close to the snake].

Geographical Variation: The Western Rattlesnake is an extremely variable species both within populations and between populations. The currently recognized distinct geographical populations (subspecies) are:

Prairie Rattlesnake (C. v. viridis): Usually with greenish tinge. Blotches usually well defined and accented with lighter margins Range: Through the central and western Great Plains from southern Canada in the north to New Mexico and Texas in the south.

Grand Canyon Rattlesnake (C. v. abyssus): Body color red or salmon. Range: Grand Canyon.

Arizona Black Rattlesnake (C. v. cerberus): A dark subspecies which may be dark gray, brown, olive, or black. Blotches on the back very dark and large, may be separated only by light lines. Range: Mountains of central and southern Arizona.

Midget Rattlesnake (C. v. concolor): A small rattlesnake rarely exceeding 24 inches in length. Color cream-yellow to tan. Blotches only slightly darker than the ground color, sometimes near absent.

Southern Pacific Rattlesnake (C. v. helleri): Similar to the Arizona Black Rattlesnake but usually lighter. Terminal dark ring of the tail about twice as long as in other populations. Range: Kern and San Luis Obispo Counties in California southward into Baja California.

Northern Pacific Rattlesnake (C. v. oreganus): Similar to the "Southern Pacific Rattlesnake", but tail rings better defined and terminal dark ring not much wider than the other dark tail rings. Range: Pacific Northwest southward to northern and central California.

Great Basin Rattlesnake (C. v. lutosus): Ground Color yellow to light tan or gray. Dark blotches about as wide as the spaces between them. Range: Great Basin region of the United States.

Hopi Rattlesnake (C. v. nuntius): A small population (rarely over 24 inches) with red-brown blotches with well defined light other margins. Range: Nnortheastern Arizona.

Range (see map below left): The Western Rattlesnake has a wide distribution covering most of the western and central United States although it is absent from the Mojave Desert region of California, western and eastern Arizona. It also seems to be missing from the western parts of Wyoming and Colorado.

Habitat: This species occurs in a wide variety of habitats, although most habitats are on the dry side. It is found in prairie, forest to near the timber line, scrub deseret. It is commonly found in rocky areas such as talus slopes and rocky canyons.

Food:  Small mammals, birds, other snakes, frogs, and lizards.

Behavior:  The Western Rattlesnake is an aggresive species and should be avoided. The species commonly overwinters in large numbers in a common den in the northern parts of its range. In some parts of its range the species may spend time in old mammal burrows.

Reproduction:  Live bearing with the female produceding 1 to 25 young each year. Young are usually born between August and October.

NOTE: The taxonomic treatment of the species here treated as Crotalus viridis, is currently in turmoil. The first split in the "species" came between the Prairie Rattlesnake (including the Hopi Rattlesnake) and the remaining subspecies. Thus Crotalus viridis became the Prairie Rattlesnake and the remaining subspecies were treated as Crotalus oreganus with the common name Western Rattlesnake. Very recently (2007), however, all of the subspecies of "Crotalus oreganus" have been elevated to species level in one revision resulting in the final breakup of Crotalus viridis into 7 species. All of these studies are based on molecular or morphological studies. Reproductive isolation or selective disadvantage of the hybrids produced between "species" has not been demonstrated. Therefore, for the moment, I am continuing to treat the Western Rattlesnake as a single species until some consensus has been reached in the community of snake systematists.

Western Rattlesnake (Crotalus viridis)

Similar Species:

Red Diamond Rattleshake (Crotalus ruber)