The great California herpetologist and rattlesnake expert Laurence Klauber left this little piece of herpetological history on a support column underneath a highway bridge in the San Diego County desert. He wrote: "L. Klauber caught Crotalus m. pyrrhus here, 1953." It had remained untouched for almost 50 years when I first saw it. When I returned a year later to take a picture, it was partly painted over as you can see here. A few years later it was completely painted over, but Klauber's essential book on rattlesnakes still remains.
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.
A coiled Southwestern Speckled Rattlesnake rattles, uncoils, and crawls into a bush. (Some loud background noise has been deleted in the middle of the video.)
A speckled rattlesnake crawls across a road and up into a bush in Imperial County.
A speckled rattlesnake rattles from up in a bush in Imperial County.
A large adult speckled rattlesnake rattling and crawling away on a windy night.
Anza-Borrego State 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 23-52 inches in length (58-132 cm) averaging 2 - 3.5 feet.
Young 8.5 - 10.5 inches.
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.
Pupils are elliptical.
Scales are keeled.
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.
Long, hollow, movable fangs connected to venom glands inject a toxic venom which quickly immobilize the prey. The snake can control the amount of venom injected and the fangs are replaced if broken. Bites on humans are potentially dangerous without immediate medical treatment.
Even a dead snake can bite and inject venom if the jaws reflexively open when they are touched.
Color and Pattern
Shows a great variety of body coloration which usually allows the snake to blend into its environment, from off-white, yellowish, gray, tan, pinkish, pale orange, to brown. Snakes from dark lava bed environments can be almost all black.
The body is marked with a vague pattern consisting of dark speckled banded markings.
Dark and light rings surround a thick tail.
The tail rings are in considerable color contrast with the body color, with the terminal rings being black and with an ash-gray ground color on the tail often present. Compare with the tail and rattle of the similar species C. stephensi.
Young
Newborn snakes do not have a rattle - just a single button which does not make a sound.
Similar Snakes
Found in sympatry with other species of rattlesnakes, including Crotalus ruber,Crotalus oreganus helleri, Crotalus atrox, Crotalus scutulatus and Crotalus cerastes. Can be differentiated from these species by color, pattern, and tail rings, and the lack of horns over the eyes.
Very similar to Crotalus stephensi, which was once thought to be the same species. Information on differentiating the two species can be found here.
Life History and Behavior
Activity
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.
An ambush hunter, it may wait 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. Prey is also found while the snake is actively moving.
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.
Bites that inject venom into humans are 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. Juveniles are born with only a silent button at the end of the tail.
A new rattle segment is added each time the skin is shed, which can be more than one time per year.
Diet and Feeding
Eats small mammals, lizards, and birds.
Heat sensing pits on the sides of the head help the snake to locate prey by their warmth.
Long, hollow, movable fangs connected to venom glands inject a very toxic venom which quickly immobilize prey.
The snake can control the amount of venom injected and the fangs are replaced if broken.
An ambush hunter, it may wait 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. Prey is also found while the snake is actively moving.
Rattlesnakes are ovoviparous. 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.
Two to 12 young are born in July or August. (Stebbins & McGinnis, 2013)
Male "Combat Dance"
Adult males engage in a ritual "Combat Dance" during the spring breeding season and at other times. Throughout much of history this activity was presumed to be a mating male and female instead of two competing males. Despite the common name, it is not combat as neither male is injured. And it's not a dance, it's essentially a wrestling match in which necks and forebodies are intertwined, with the stronger snake slamming the smaller one to the ground until the weaker snake leaves the area. Most bouts end in a draw.
"Certainly the presence of a female is not necessary to stimulate males to dance."
"Dancing is not restricted to a single season of the year."
(Klauber, 1982)
Habitat
Associated mostly with arid areas strewn with rocks and boulders - alongside buttes, mesas, and desert outcroppings, but sometimes found on loose soil. Occurs in areas vegetated by sagebrush, creosote, thornscrub, chaparral, pinon-juniper woodland, succulent desert.
Geographical Range
The species Crotalus pyrrhus ranges from southern California south to Baja California del Sur, Mexico, and north and east into Nevada, Utah and Arizona.
Traditional range maps for this snake (when it was C. mitchellii pyrrhus) including my former maps, show it ranging west in the Mohave Desert north of the San Gabriel Mountains to the Tehachapi mountains, but I have found no museum records for this area and no observations in iNaturalist from farther west than the Victorville area, so I no longer show it occurring in this area. There is a museum specimen from Los Angeles County but there is no more specific location given other than the county, so I don't know if it is from this area.
Elevational Range
From
sea level to 8,000 ft. (2,440 m)
Notes on Taxonomy
MEIK et al in 2015 demonstrated that C. pyrrhus is a species distinct from C. mitchellii of Baja California.
In a 2007 paper, * using molecular data, Douglas et al showed that this snake is a distinct species, not a subspecies of Crotalus mitchellii.
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.
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.
* Douglas, Michael E., Marlis R. Douglas, gordon W. Schuett, Louis W. Porras, and Blake L. Thomason. Genealogical Concordance between Mitochondrial and Nuclear DNAs Supports Species Recognition of the Panamint Rattlesnake (Crotalus mitchellii stephensi). Copeia, 2007(4), pp. 920–932.
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 animal is not included on the Special Animals List, which indicates that there are no significant conservation concerns for it in California.
Red: Range of this species in California
