San Diego Natural History Museum--Your Nature ConnectionSDNHM Field Guide
Red Diamond Rattlesnake, near Barret Lake, photo by Jim Melli 1985

Crotalus exsul (=Crotalus ruber)
Red Diamond Rattlesnake


Crotalus comes from the Greek crotalon, a rattle or little bell; exsul comes from the Latin exul, meaning to be exiled or banished, in reference to the location of the holotype specimen collected from Isla Cedros, Mexico.

The previously used name ruber means "red," which is quite descriptive of individuals from the northern portion of their range. Recently, it was determined that the two species (C. ruber and C. exsul) represented only a single form. The name exsul is choosen because it was the first of the two to be described (it has priority).


The Red Diamond Rattlesnake is one of the largest rattlers in the region. The longest on record measures a little over 5 feet, but most individuals are in the 2 1/2 to 3 1/2 foot range.

Its coloration sets it apart from other rattlesnake species in our area, and makes it easy to recognize. The body is a reddish or tan color with a light edged diamond pattern on its back. A black and white ringed tail finishes the effect. The young start their lives gray, and become redder as they mature. Some individuals from the inland valleys develop a striking brick red color. The Red Diamond Rattlesnake's size and beauty make it a very impressive animal, especially when seen in the wild.

Range and Habitat

This rattler ranges through Southern California from San Bernardino County to Cabo San Lucas, Baja California Sur. In the northern part of its range the Red Diamond occupies environments from the coast to the desert slopes of the mountains, but avoids the lower desert flats and elevations above 5,000 feet. In Baja California it inhabits most of the peninsula from the Pacific to the Gulf of California, including some of the gulf islands.

The Red Diamond is more commonly found in areas of rock and brush than in grasslands or cultivated areas.

Natural History

The first warm days of February and March bring the Red Diamond Rattlesnakes out of their winter retreats, and onto southern slopes and rock outcrops to bask in the sun. As the weather warms, Red Diamonds become more active and search for food and mates. In desert environments and in hot weather, they are most active at dusk and at night.

Their diet consists of rodents, rabbits, and other small mammals, but can include birds.

A female Red Diamond Rattlesnake may produce from 3 to 20 young, which are born in the summer.

This particular rattlesnake is noted for its mellow disposition, but individuals vary. Some may not even rattle when encountered, while others may be quite nasty. This snake -- like all rattlesnakes -- should be treated with a healthy dose of caution and respect.

Conservation Status

The Red Diamond Rattlesnake is currently a Federal Special Concern species (FSC) and a California Special Concern species (DFG-CSC).

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 suspectible to being overlooked by conservation-minded biologists.

Text and photo contributed by Jim Melli.

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