Adult, Imperial County desert, found in ambush mode coiled up in the sand between rocks at night.
Adult, San Diego County desert
Adult, San Diego County desert
Adult, coastal San Diego County
Adult, Imperial County desert
Adult, crossing a popular hiking trail in coastal San Diego County in the middle of the afternoon, managing
to avoid observation by all visitors except myself. You can see the tracks it made in the sand on the right.
Habitat, Riverside County
riparian desert foothills
Short Videos and Sound
A large old Red Diamond Rattlesnake rattles on top of a boulder in coastal San Diego County.
A close view of a rattling Red Diamond Rattlesnake's tail.
A large adult Red Diamond Rattlesnake crawls up some large boulders at the edge of a desert wash in San Diego County. After trying to climb up past the top of the boulder, it crawled back down. Despite the bright lights, it did not appear to notice me and continued its nocturnal wandering.
A Red Diamond Rattlesnake crawls across the hot sand at mid day in San Diego County, then takes shelter between some rocks.
A Red Diamond Rattlesnake found on a desert road at night.
Listen to a rattlesnake rattling.
California State Park warning sign.
Click the picture to see more rattlesnake signs.
Rattlesnakes are important members of the natural community. They will not attack, but if disturbed or cornered, they will defend themselves. Reasonable watchfulness should be sufficient to avoid snakebite. Give them distance and respect.
"Rattlesnakes are also among the most reasonable forms of dangerous wildlife: their first line of defense is to remain motionless; if you surprise them or cut off their retreat, they offer an audio warning; if you get too close, they head for cover. Venom is intended for prey so they're reluctant to bite, and 25 to 50 percent of all bites are dry - no venom is injected."Leslie Anthony. Snakebit: Confessions of a Herpetologist. Greystone Books, 2008.
Rattlesnake bites can be extremely dangerous, but rattlesnakes should not be considered as vicious and always ready to attack without provocation. They will not strike without a reason, but they will aggressively defend themselves. They are often portrayed with the body partly coiled, the tail rattling loudly, and the head up ready to strike. This display is a warning not to come any closer or they will strike; a defensive behavior that some rattlesnakes use when they sense that crawling away would put them in danger. If they are given some space and some time to escape to a safe place, they will usually crawl away as fast as possible.
Because they cannot crawl to safety as fast as some snakes, rattlesnakes often use their cryptic color and pattern to blend into their surroundings in order to hide from their prey and from other animals that could threaten them. They often hunt by sitting still and waiting for a warm-blooded prey animal to pass close enough for the snake to strike it. Sometimes a passing human will be struck instead, mistaken for food. When they sense the presence of something that might threaten them, rattlesnakes often lie still to avoid detection and do not rattle, because that would give away their location. At other times they rattle loudly, sometimes from a good distance, to warn potential enemies of their presence. In both cases they are doing everything they can to avoid confrontation and to avoid striking and biting and using up their valuable supply of venom which they need to kill and digest their food.
A bite by this snake can be very dangerous without immediate medical treatment. Treatment can require hospitalization and great expense.
Adults are 30 - 65 inches in length ( 76 - 165 cm) typically 2 - 4.5 feet long.
Young are about 12 inches long.
A long, heavy-bodied pit viper, with a thin neck, a large triangular head, and a rattle on the end of the tail consisting of loose interlocking hollow segments.
A new rattle segment is added each time the skin is shed, which can be more than one time per year.
Pupils are elliptical.
Scales are keeled.
Color and Pattern
Variable in ground color; pink, reddish-tan, reddish-brown or brick red.
Diamond-shaped blotches, usually with light edges, mark the back.
The underside is usually dull yellow and unmarked.
Black and white rings surround a thick tail.
(Unlike most snake species, males of this species tend to be larger in body length than females.)
Juveniles are duller in coloring than adults.
Newborn snakes do not have a rattle - just a single button which does not make a sound.
Similar to and easily confused with the Western Diamond-backed Rattlesnake, but in California the ranges of these two snakes barely meet, and the Western Diamond-backed Rattlesnake in Calfornia does not typically show a red color phase.
Life History and Behavior
Primarily nocturnal and crepuscular during periods of excessive daytime heat, but also active during daylight when the temperature is more moderate or when in the comparatively cooler shaded areas of boulder fields.
Not active during cooler periods in Winter.
Terrestrial, but may partially climb shrubs or trees.
Sound - The Rattle
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 and Feeding
Eats small mammals, including ground squirrels, wood rats, and rabbits, lizards, and birds.
Prey is found when actively moving, or by ambush, where the snake waits 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.
Dugan and Hayes, 2012, found that this species specializes on mammalian prey, with terrestrial rodents the primary prey source. Wood rats were the most abundant prey species, followed by kangaroo rats, pocket mice, and deer mice. Coastal populations average longer in body size and eat a higher proportion of larger rodents than snakes from desert populations.
(Adult California Ground Squirrels are immune to rattlesnake venom and will intensely confront any snake they feel to be a threat.)
Breeding occurs in the spring. Male rattlesnakes search extensively for females during the mating season while females do not actively search for males. Male to male combat occurs.
Live-bearing; young are born July - September.
Found in southwestern California, from the Morongo Valley west to the coast and south along the peninsular ranges to mid Baja California.
Inhabits arid scrub, coastal chaparral, oak and pine woodlands, rocky grassland, cultivated areas.
On the desert slopes of the mountains, it ranges into rocky desert flats.
Notes on Taxonomy
Previously recognized as a subspecies of Crotalus ruber: Crotalus ruber ruber. Some taxonomists regard this snake as a subspecies of Crotalus exsul labelling it Crotalus exsul ruber.
When a Pet Gets Snake Bitten: The amazing story of Andy Cat, a very lucky cat who was bitten by a rattlesnake and survived, thanks to the smart actions of its owners.
Stebbins, Robert C., and McGinnis, Samuel M. Field Guide to Amphibians and Reptiles of California: Revised Edition (California Natural History Guides) University of California Press, 2012.
Stebbins, Robert C. California Amphibians and Reptiles. The University of California Press, 1972.
Stebbins, Robert C. A Field Guide to Western Reptiles and Amphibians. 3rd Edition. Houghton Mifflin Company, 2003.
Behler, John L., and F. Wayne King. The Audubon Society Field Guide to North American Reptiles and Amphibians. Alfred A. Knopf, 1992.
Powell, Robert., Joseph T. Collins, and Errol D. Hooper Jr. A Key to Amphibians and Reptiles of the Continental United States and Canada. The University Press of Kansas, 1998.
Bartlett, R. D. & Patricia P. Bartlett. Guide and Reference to the Snakes of Western North America (North of Mexico) and Hawaii. University Press of Florida, 2009.
Bartlett, R. D. & Alan Tennant. Snakes of North America - Western Region. Gulf Publishing Co., 2000.
Brown, Philip R. A Field Guide to Snakes of California. Gulf Publishing Co., 1997.
Ernst, Carl H., Evelyn M. Ernst, & Robert M. Corker. Snakes of the United States and Canada. Smithsonian Institution Press, 2003.
Wright, Albert Hazen & Anna Allen Wright. Handbook of Snakes of the United States and Canada. Cornell University Press.
Ernst, Carl. H. Venomous Reptiles of North America. Smithsonian Institution Press, 1999.
Hayes, William K., Kent R. Beaman, Michael D. Cardwell, and Sean P. Bush, editors. The Biology of Rattlesnakes. Loma Linda University Press, 2009.
Hubbs, Brian R., & Brendan O'Connor. A Guide to the Rattlesnakes and other Venomous Serpents of the United States. Tricolor Books, 2011.
Klauber, Laurence M. Rattlesnakes. University of California Press. (Abridged from the 1956 two volume Rattlesnakes:
Their Habits, Life Histories, and Influence on Mankind.) University of California Press, 1982.
Rubio, Manny. Rattlesnake - Portrait of a Predator. Smithsonian Institution Press, 1998.
Walls, Jerry G. Rattlesnakes: Their Natural History and Care. T. F. H. Publications, Inc., 1996.
Eric A. Dugan and William K. Hayes. Diet and Feeding Ecology of the Red Diamond Rattlesnake, Crotalus Ruber (Serpentes: Viperidae)
Herpetologica, 68(2), 2012, 203–217 E 2012 by The Herpetologists’ League, Inc.
Eric A. Dugan, Alex Figueroa, and William K. Hayes. Home Range Size, Movements, and Mating Phenology of Sympatric Red Diamond (Crotalus ruber) and Southern Pacific (C. oreganus helleri) Rattlesnakes in Southern California. Pp. 353-364 in W. K. Hayes, K. R. Beaman, M. D. Cardwell, and S. P. Bush (eds.), The Biology of Rattlesnakes. Loma Linda University Press. 2008.
The following status listings come from the Special Animals List and the Endangered and Threatened Animals List which are published by the California Department of Fish and Wildlife.