Sidewinder tracks in the sand,
with their characteristic "J" shape.
Tail and Rattle
Black coloring at the base of the rattle.
(Compare with the brown coloring of the Mohave Desert Sidewinder.)
How to Tell the Difference Between Rattlesnakes and Gophersnakes
Harmless and beneficial gophersnakes are sometimes mistaken for dangerous rattlesnakes. Gophersnakes are often killed unnecessarily because of this confusion.
(It's also not necessary to kill every rattlesnake.)
It is easy to avoid this mistake by learning to tell the difference between the two families of snakes. The informational signs shown above can help to educate you about these differences. (Click to enlarge).
If you can't see enough detail on a snake to be sure it is not a rattlesnake or if you have any doubt that it is harmless, leave it alone.
You should never handle a snake unless you are absolutely sure that it is not dangerous.
Habitat
Habitat, Imperial County desert
Habitat, San Diego County desert
Habitat, San Diego County desert
Habitat, Imperial County desert
Habitat, Imperial County desert
Habitat, Imperial County desert
Habitat, Inyo County
Habitat, San Diego County desert
Short Videos and Sound
A Colorado Desert Sidewinder found on a road at night rattles and sidewinds.
A Colorado Desert Sidwinder sidewinding at night.
A Colorado Desert sidewinder crawls with its unique sideways locomotion.
Listen to the faint rattling of a sidewinder.
California park warning sign.
Click the picture to see more
rattlesnake warning 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.
Rattlesnakes are typically described as poisonous, but they are actually venomous.
A poisonous snake is one that is harmful to touch or eat. A venomous snake injects dangerous venom into its victim.
A bite from a rattlesnake can be extremely dangerous, but rattlesnakes should not be characterized as aggressive and vicious, striking and biting without provocation, as they are often shown. If rattlesnakes are given some space and enough time to escape to a safe place, they will usually just crawl away as fast as possible to avoid confrontation. Rattlesnakes will not strike without a reason: they will strike at a potential meal and they will defend themselves from anything they perceive as dangerous. They avoid striking and biting because it uses up their valuable supply of venom which they need to kill and digest their food.
Rattlesnakes are often portrayed with the body partly coiled, the tail rattling loudly, and the head raised up and ready to strike, but they do not need to coil up this way to strike and bite. This display is a warning not to come any closer. It's a defensive behavior that some rattlesnakes use when they sense that crawling away would put them in danger of attack.
Rattlesnakes do not always rattle a warning. Sometimes they rattle loudly to warn potential enemies of their presence, but other times they remain silent when they sense a threat, choosing to remain still to rely on their cryptic color and pattern to let them blend into their surroundings to hide from the threat. Making a noise in this situation risks advertising their presence. They also use their natural camouflage to hunt by sitting still, without rattling, trying to remain invisible as they wait for a warm-blooded prey animal to pass close enough to strike.
Description
Dangerously Venomous
A bite from this snake can cause death or serious illness or injury in humans that may require immediate medical care.
(Commonly called a "poisonous" snake to indicate that its bite is dangerous, but that is not correct. It should be called a "venomous" snake. A poisonous snake can harm you if you eat it. A venomous snake can harm you if it bites you.)
Size
Adults are 17 - 33 inches. (43 - 84 cm). Snakes encountered will generally be 12 - 18 inches.
Juveniles are about 7 inches at birth.
Appearance
A heavy-bodied venomous pit viper with a thin neck, a large triangular head, and a thick tail with a rattle on the end made of loose interlocking 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.
The supraocular scale over each eye is enlarged and raised up over the eye giving the appearance of a "horn" over each eye. These scales can fold down over the eyes to protect them when the snakes is buried or crawling in underground burrows.
Rattlesnakes are "pit vipers" which means they have two pits that are used to sense heat when hunting warm-blooded prey - with one pit on each side of the front of the head above the mouth.
Color and Pattern
Pale cream, tan, brown, pink, or grayish back color usually closely matches the soil surface allowing the snake to blend in with the background.
Around 40 darker blotches on the back.
A dark stripe extends through each eye.
Young
Juveniles are born with only a single rattle button at the end of the tail.
The dark segment of the rattle closest to the body on an adult C. c. laterorepens is black.
The dark segment of the rattle closest to the body on an adult C. c. cerastes is brown,
The dark rattle segment may not become fully black on C. c. laterorepens until the snake is an adult with 3 or more rattle segments.
The last dark marks on the tail do not always correspond to the color of the dark rattle segment.
C. c. cerastes has 21 scale rows. C. c. laterorepens has 23 scale rows. C. c. laterorepens has a higher number of ventral scales than C. c. cerastes.
Primarily nocturnal and crepuscular during periods of excessive daytime heat, but also active during daylight when the temperature is more moderate.
Not active during cooler periods in Winter.
Locomotion
Moves with a sidewinding locomotion, throwing raised loops of the body to the side to push itself forward in an s-sheped curve. A sidewinders trail looks like a series of parallel j-shaped lines pointing roughly 45 degrees from the direction of movement.
Fangs and Venom
Two large hollow movable fangs are located at the front of the upper jaw are folded backwards when not used. The fangs are connected to venom glands so that when the snake bites, the fangs swing forward rapidly to stab the prey and inject a toxic venom that quickly immobilizes the prey. A rattlesnake can control the amount of venom injected. The fangs can be replaced if broken.
Though the amount of venom a sidewinder injects is relatively small and rarely deadly, bites on humans are still potentially dangerous without immediate medical treatment.
Sometimes a rattlesnake bites but does not inject venom. These are called "dry bites." A dry bite may still require medical attention.
Even a dead snake can bite and inject venom if the jaws open and close reflexively when they are touched.
A bite from any kind of rattlesnake of any age or any size should be treated as a serious medical emergency, but the bite of a juvenile rattlesnake is not more dangerous than the bite of an adult.
Experts disagree whether or not juvenile rattlesnake venom is more potent than adult rattlesnake venom, but this does not really make much difference in the severity of a bite.
While adult rattlesnakes can control the amount of venom they inject depending on their needs (small animals need less venom, a defensive or warning bite may need no venom, etc.), it is often assumed that juvenile rattlesnakes do not have the same ability and that they always inject the full amount of venom they have available. Some studies show this is not true.
There is also no proof that adult rattlesnakes are more likely than juveniles to bite without injecting venom when they are biting as a warning. Regardless of these things, adults have far more venom to inject than juveniles so the potential danger from the bite of an adult is significantly higher than the danger from the bite of a juvenile. Even when an adult does not inject the full amount of venom it has available, it most likely injects more venom than a juvenile would inject.
Venomous snakes are immune to the venom of their own species, so if a snake is bitten during interactions with other snakes of its species during territorial fights or during mating or if it accidentally bites itself, it will not suffer from the venom. However, they are not typically immune to the venom of other species of snakes.
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. Newborn snakes have only one rattle segment which does not make a sound.
Diet and Feeding
Eats mainly lizards when young, and eats increasingly larger prey including small rodents when grown.
An ambush hunter, it sits buried beneath the surface of loose sand with just the top of the head showing, near kangaroo rat warrens, and lizard or rodent trails, then strikes at and releases the prey. The snake then follows the trail of the envenomated animal and swallows it whole.
Young snakes may use their tail to lure their prey (caudal luring.) They coil up and lie still, raise up the tail, and wiggle it.
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.
Rattlesnakes are ovoviviparous. The mother keeps her fertilized eggs inside her body and gives birth to living young.
Females probably start bearing young at three years of age and breed annually. (Klauber, 1982)
Mating occurs in the spring.
2 to 18 young are born from July to September. (Stebbins & McGinnis, 2013)
Habitat
Inhabits primarily areas of wind-blown sands, especially where sand hummocks are topped withvegetation. Also found in hardpan, open flats, rocky hillsides, and other desert areas, especially those grown with creosote bush, where the terrain is open, not obstructed by rocks or vegetation, allowing the broad sidewinding locomotion.
Geographical Range
This subspecies, Crotalus cerastes laterorepens - Colorado Desert Sidewinder, is found in southeastern California - roughly south of the San Bernardino County line and west to the slopes of the peninsular ranges.
The species Crotalus cerastes - Sidewinder, is found in the Southern California deserts, east through southern Nevada to extreme southwestern Utah, into western Arizona, and south into northeast Baja California Mexico, and northwest Sonora, Mexico.
Notes on Taxonomy
According to SSAR Herpetological Circular No. 43, 9/17 -
"Douglas et al. (2006, Mol. Ecol. 15: 3353–3374), using mtDNA, found several geographically distinct lineages within C. cerastes. Only one of these lineages corresponded to a recognized subspecies. (C. c. laterorepens).
Crotalus - Greek - krotalon - a rattle - refers to the rattle on the tail
cerastes - Greek - kerastes - horned - referring to the "horns" on head
laterorepens - Latin - later - side and repens - creeping or crawling - refers to the curious style of "sidewinder" locomotion
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.
Flaxington, William C. Amphibians and Reptiles of California: Field Observations, Distribution, and Natural History. Fieldnotes Press, Anaheim, California, 2021.
Samuel M. McGinnis and Robert C. Stebbins. Peterson Field Guide to Western Reptiles & Amphibians. 4th Edition. Houghton Mifflin Harcourt Publishing Company, 2018.
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, 1957.
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, 1957.
Joseph Grinnell and Charles Lewis Camp. A Distributional List of the Amphibians and Reptiles of California. University of California Publications in Zoology Vol. 17, No. 10, pp. 127-208. July 11, 1917.
Conservation Status
The following conservation status listings for this animal are taken from the January 2024 State of California Special Animals List and the January 2024 Federally Listed Endangered and Threatened Animals of California list (unless indicated otherwise below.) Both lists are produced by multiple agencies every year, and sometimes more than once per year, so the conservation status listing information found below might not be from the most recent lists. To make sure you are seeing the most recent listings, go to this California Department of Fish and Wildlife web page where you can search for and download both lists: https://www.wildlife.ca.gov/Data/CNDDB/Plants-and-Animals.
A detailed explanation of the meaning of the status listing symbols can be found at the beginning of the two lists. For quick reference, I have included them on my Special Status Information page.
If no status is listed here, the animal is not included on either list. This most likely indicates that there are no serious conservation concerns for the animal. To find out more about an animal's status you can also go to the NatureServe and IUCN websites to check their rankings.
This snake is not included on the Special Animals List, which indicates that there are no significant conservation concerns for it in California.
Orange: Range of this subspecies in California
