San Diego Natural History Museum--Your Nature ConnectionSDNHM Field Guide
Western Diamondback Rattlesnake, photographed by BDH

Crotalus atrox
Western Diamondback Rattlesnake


Crotalus comes from the Greek crotalon, meaning a rattle or little bell; atrox comes from the Latin atroc, meaning hideous or savage. In Spanish, rattlesnakes are known as La Vibora de cascabel.


The Western Diamondback is the largest rattlesnake in western North America—ranging in size from 3-feet to as long as 7-feet! Like all rattlesnakes, this species has a triangular shaped head, keeled scales, and heat seeking "pits" just below their nostrils. A new segment to the rattle is added during each shed of the skin.

The coloration of the Western Diamondback can vary from gray, brown, pink, or yellowish above, with light brown to blackish diamond shaped blotches which tend to fade towards the tail. The tail is ringed with black and white or light gray. A light stripe behind the eye meets the corner of the mouth.

Range and Habitat

Western Diamondback Rattlesnake, photographed by BDH

This species ranges throughout southwestern United States and northeastern México. In our region it can be found in mountain and desert areas of southeastern California and extreme northeastern Baja California. Some accounts list this species in the deserts of San Diego County, however, these records are dubious. In the Gulf of California, the Western Diamondback can be found on Islas Tiburón, Santa Cruz, Dátil, and San Pedro Mártir.

This species inhabits arid and semiarid areas including mountains, desert brush, rocky canyons, and vegetated rocky foothills less then 1000 feet in elevation. There are occasional reports of individuals found in higher elevations.

Natural History

Rattlesnakes coil and rattle their tail as a defensive warning to potential predators. Sometimes, the snake will elevate itself off the ground to make itself look bigger and more fearsome.

The Western Diamondback is a stubborn snake and has a tendency to stand its ground. As with all rattlesnakes, this species is venomous. It ranks as one of the most dangerous snakes in the world. Bites are serious and potentially deadly if medical treatment is not reached immediately.

Behavior: Rattlesnakes are principally nocturnal, but will be active in the daytime during the spring months when temperatures are cooler at night. This species is known to bask in the late afternoon sun.

Diet: Its diet consists of rabbits, mice, rats, gophers, sparrows, and ground squirrels.

Breeding: This snake is viviparous, having 4 to 25 live young, 8-12 inches long. The babies are born during late July or August.

Conservation Status

There have been no proposed conservation plans. Because of widespread negative attitudes towards snakes, very few conservation programs, worldwide, have been created. A much higher percentage of snakes are threatened with extinction than is currently recognized. Therefore, snakes are particularly susceptible to being overlooked by conservation-minded biologists.

Text by David Gonzalez and Bradford Hollingsworth.
Photos by Bradford Hollingsworth.

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