CaliforniaHerps.com

A Guide to the Amphibians
and Reptiles of California


Western Diamond-backed Rattlesnake - Crotalus atrox

Baird and Girard, 1853
Click on a picture for a larger view



Western Diamond-backed Rattlesnake Habitat range map
Range in California: Red




Rattlesnake Sounds and Video




observation link






Venomous and Potentially Dangerous!


Western Diamond-backed Rattlesnake
Western Diamond-backed Rattlesnake Western Diamond-backed Rattlesnake Western Diamond-backed Rattlesnake
Adult, Riverside county
© William Flaxington
Adult, Riverside county
© William Flaxington
Adult, Imperial County (Calexico)
© Tom Millington
Western Diamond-backed Rattlesnake Western Diamond-backed Rattlesnake Western Diamond-backed Rattlesnake
Adult, Riverside County
© Patrick Briggs
Adult, Riverside County
© Chad Lane
Adult, Imperial County at Colorado River 
© John Sullivan
Western Diamond-backed Rattlesnake Western Diamond-backed Rattlesnake Western Diamond-backed Rattlesnake
Adult, Riverside County. Note that the rear light stripe does not extend beyond the end of the jaw. © Patrick Briggs Top of head showing several small scales between the supraoculars.
© Patrick Briggs
Top of head showing several small scales between intraoculars.
Compare with the two large scales between the supraoculars of the Northern Mohave Rattlesnake.
  Western Diamond-backed Rattlesnake tail  
  Tail and Rattle
 
     
Western Diamond-backed Rattlesnakes From Outside California
Western Diamond-backed Rattlesnake Western Diamond-backed Rattlesnake Western Diamond-backed Rattlesnake
Adult in the typical Diamondback threatening
defensive posture, Sierra County, New Mexico.
Adult, Cochise County, Arizona
Western Diamond-backed Rattlesnake Western Diamond-backed Rattlesnake Western Diamond-backed Rattlesnake
Adult, Webb County, Texas

Adult, from just across the Colorado River from California in
La Paz County, Arizona
Adult, Presidio County, Texas
     
Feeding
Western Diamond-backed Rattlesnake Western Diamond-backed Rattlesnake Western Diamond-backed Rattlesnake
A Western Diamond-backed Rattlesnake eats a dove in Cochise County, Arizona. © Bob Herrmann
Western Diamond-backed Rattlesnake Western Diamond-backed Rattlesnake  
Juvenile eating a rodent on a road at night, Hidalgo County, New Mexico
 
   
Habitat
Western Diamond-backed Rattlesnake Habitat Western Diamond-backed Rattlesnake Habitat Western Diamond-backed Rattlesnake Habitat
Habitat, Imperial County desert Habitat, Imperial County desert Habitat, New River, Imperial County
Western Diamond-backed Rattlesnake Habitat Western Diamond-backed Rattlesnake Habitat Sonoran Gopher Snake Habitat
Habitat, Imperial County desert Habitat, Riverside County desert Habitat, Imperial County
Western Diamond-backed Rattlesnake Habitat Rattlesnake Sign  
Habitat, Imperial County desert California National Wildlife Refuge warning sign, Imperial County.

Click the picture to see more rattlesnake signs.
 
     
Short Videos and Sound
Western Diamond-backed Rattlesnake Habitat Western Diamond-backed Rattlesnake Habitat speaker icon


Several views of a Cochise County, Arizona Western Diamond-backed Rattlesnake rattling and taking a defensive pose with its head and tail elevated. A Western Diamond-backed Rattlesnake rattles in a defensive pose in Sierra County, New Mexico.   Listen to a Western Diamond-backed Rattlesnake rattle and hiss.

(This is the snake shown above in the first row, at the far right.)
     
 
rattler sign rattlesnake sign sign
  California 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.

Description

Dangerously Venomous (Poisonous)

A bite by this snake can be very dangerous without immediate medical treatment. 
Treatment can require hospitalization and great expense.

Size
The largest rattlesnake in California, and in the West.
Adults grow to 30-90 inches (76-229 cm). Most snakes encountered are from 1 to 4 feet in length.

Appearance
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.
Usually 4 or more small scales occur on top of the head between the supraocular scales.
Color and Pattern
The ground color and the intensity of the pattern are variable, often matching the habitat; grey, brown, olive, tan, or yellowish. Diamond-shaped blotches on the back are brown or black, with light edges.

Broad black and white rings, fairly equal in width, circle a thick tail just before the rattle.
A light stripe extends from behind the eye diagonally to the upper lip in front of the end of the jaw crossing over the lip.
(The posterior light stripe of the Northern Mohave Rattlesnake extends back beyond the end of the jawand does not cross the lip.)
Young
Newborn snakes do not have a rattle - just a single button which does not make a sound.
Similar Snakes
Similar to and easily confused with the Northern Mohave Rattlesnake, though there is little range overlap in California.

See this page:
Differences Between Western Diamond-backed Rattlesnake - Crotalus atrox 
& Northern Mohave Rattlesnake - Crotalus scutulatus scutulatus


Also similar to and easily confused with the Red Diamond Rattlesnake, but in California the ranges of these two snakes barely meet, and the Red Diamond Rattlesnake is typically light reddish brown or red in color.

Life History and Behavior

Activity
Primarily nocturnal during periods of excessive daytime heat, but also active during daylight when the temperature is more moderate.
Not active during cooler periods in Winter.

Even a dead snake can bite and inject venom if the jaws reflexively open when they are touched.
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.
Defense
When disturbed, in self-defense Western Diamond-backs will often aggressively hold their ground, raising the head high in a striking coil with the tail elevated and rattling, and hissing loudly.
Diet and Feeding
Eats small mammals, birds, lizards. Juveniles sometimes eat large insects and frogs.

Pits on the sides of the head sense heat. These heat sensors help the snake to locate prey by their warmth.
Long, hollow, movable fangs connected to venom glands inject a very toxic venom which quickly immobilizes the prey.
The snake can control the amount of venom injected and the fangs are replaced if broken.

An ambush hunter, it typically sits near the trail of a mammal, waiting for it to pass by, then strikes at and releases the prey. The snake then follows the trail of the envenomated animal and swallows it whole.
Breeding
Live-bearing.
Adult male snakes engage in ritual combat mostly during the breeding season to defend territory. Necks and forebodies are intertwined, with the stronger snake slamming the smaller one to the ground until the weaker snake leaves the area.

Geographical Range
Found in southeast California in Imperial, Riverside, and San Bernardino Counties.

(The 1990 California Dept. of Fish and Game California Wildlife Habitat Relationships System range map for the species shows it ranging farther west into San Diego County, overlapping the range of C. ruber.)

Outside of California, the species ranges through much of Arizona, New Mexico, Oklahoma, and Texas, into Arkansas, and south into Mexico.

Full Species Range Map
Red = Approximate Range of Crotalus atrox - Western Diamond-backed Rattlesnake

Elevational Range
Generally found at elevations less than 1000 ft. (300 m).

Habitat
Inhabits arid and semiarid areas including mountains, deserts, canyons and rocky vegetated foothills.

Notes on Taxonomy
None

Conservation Issues  (Conservation Status)
None

Taxonomy
Family Viperidae Vipers Crotalidae - Pitvipers
Genus Crotalus Rattlesnakes Linnaeus, 1758
Species


atrox Western Diamond-backed Rattlesnake Baird and Girard, 1853
Original Description
Baird and Girard, 1853 - Cat. N. Amer. Rept., Pt. 1, p. 5

from Original Description Citations for the Reptiles and Amphibians of North America © Ellin Beltz

Meaning of the Scientific Name
Crotalus - Greek - krotalon - a rattle - refers to the rattle on the tail
atrox
- Latin - atrox dark, fierce, savage - referring to the sometimes savage disposition of this species

from Scientific and Common Names of the Reptiles and Amphibians of North America - Explained © Ellin Beltz

Alternate Names
Western Diamondback Rattlesnake

Related or Similar Neighboring California Snakes
C. ruber - Red Diamond Rattlesnake
C. s. scutulatus - Northern Mohave Rattlesnake
C. c. laterorepens - Colorado Desert Sidewinder
C. c. cerastes - Mohave Desert Sidewinder
C. m. pyrrhus - Southwestern Speckled Rattlesnake
C. o. helleri - Southern Pacific Rattlesnake

More Information and References
California Department of Fish and Wildlife

Living With Rattlesnakes

California Department of Fish and Game: Rattlesnakes in California

University of California: Rattlesnakes Management Guide

Tucson Herpetological Society: Living With Venomous Reptiles pdf

Florida Museum of Natural History: How to Get Along with Snakes

Southwestern Field Herping Associates: Venomous Snake Safety

Internet Center for Wildlife Damage Management - Rattlesnake Control / Snake Control


Rattlesnake Bites


California Poison Control System (search for "rattlesnake bite")

University of Arizona: Rattlesnakes

Justin Schwartz' Rattlesnake Bite Story and Pictures

Sean Bush MD: Venom ER - When snakes strike!

eNature - How to Avoid Snakebites and How to Treat One

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.



Conservation Status

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.


This snake is not included on the Special Animals List, which indicates that there are no significant conservation concerns for it in California.


Organization
Status Listing
U.S. Endangered Species Act (ESA) None
California Endangered Species Act (CESA) None
California Department of Fish and Wildlife None
Bureau of Land Management None
USDA Forest Service None

 

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