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Venomous and Potentially Dangerous!
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| Adult, San Diego County |
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Juvenile with yellow tail, Los Angeles County.
(Note that the rattle consists of only one segment which does not produce a sound.) |
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This adult was found crossing a road one morning in San Diego County when it made a quick
U-turn and crawled back into a bush. You can also see the tracks it made in these photos. |
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Adult, Ventura County
© Patrick Briggs
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Adult, Ventura County
© Patrick Briggs |
Adult, Ventura County
© Patrick Briggs |
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Adult, Riverside County
© Michael Clarkson |
Juvenile, San Bernardino County
© Patrick Briggs |
Captive adult, courtesy of the Arizona-Sonora Desert Museum |
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Juvenile, San Diego County. © Lori Paul |
Intergrade with C. o. oreganus, Santa Barbara County © Benjamin German |
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Adult, Santa Catalina Island
© Nathan Smith |
Adult, Santa Catalina Island
© Nathan Smith |
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| Melanistic patternless adult, Riverside County. © Tony Covell |
Melanistic Adult, Ventura County
© Patrick Briggs |
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Melanistic adult, San Gabriel Mountains, Los Angeles County. © Lori Paul
This snake had a completely dark belly. |
12 inch juvenile, Orange County, flattening its body to appear larger. © David Fong |
Tail and Rattle |
| Breeding Behavior |
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Steve Bledsoe, ©, photographed these two helleri mating in March in San Diego County. |
Males in combat, Ventura County
© 2006 Steve Broggie |
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Two adults, probably a mating pair, in San Diego County, as found underneath a board. |
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San Diego County park warning sign.
Click the picture to see more
rattlesnake signs. |
Sign at Santa Barbara
County rest area |
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| Short Video |
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A Southern Pacific Rattlesnake poses and rattles and crawls away at night in Los Angeles County. |
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| Habitat |
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Habitat, Los Angeles County mountains |
Habitat, San Diego County coastal scrub |
Habitat, coastal San Diego County.
(This location was bulldozed and developed a few years later.)
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Habitat, coastal Riverside County |
Coastal San Diego County grassland habitat that is rapidly disappearing due to development. © Brian Hinds |
Habitat, riparian canyon, Los Angeles County |
Sounds |
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Listen to the rattling of a captive adult (shown above) courtesy of the Arizona-Sonora Desert Museum. © Jeff Rice / Western Soundscape Archive Not to be used without permission. |
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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.
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Description |
Venomous |
| The venom of this snake is potentially dangerous to humans. |
| Size |
| Adults 30 - 44 inches long, sometimes up to 54 inches. Newborns about 10 inches long. |
| Appearance |
A heavy-bodied, venomous pit viper, with a thin neck and a large triangular head. Pupils are elliptical. Scales are keeled.
Ground color is brown to olive-brown. Dark brown blotches, completely outlined by light pigment, mark the back. These blotches turn to bars toward the tail, which is surrounded with dark rings. The last ring is not well-defined and is more than twice the width of the other rings. Young have a bright yellow tail. The underside is pale, sometimes weakly mottled.
A rattle, consisting of loose interlocking segments, usually occurs at the end of the tail. A new rattle segment is added each time the skin is shed. Newborn snakes do not have a rattle - just a single button which does not make a sound.
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. 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. |
| Behavior |
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.
Prey is found while the snake is 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.
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 |
| Eats birds, lizards, snakes, frogs, insects, and small mammals, including mice, rats, rabbits, hares, and ground squirrels. (Adult California Ground Squirrels are immune to rattlesnake venom and will intensely confront any snake they feel to be a threat.) |
| Reproduction |
| Live-bearing; young born August - October. Known to hybridize with the Northern Mohave Rattlesnake where their ranges overlap in the Antelope Valley. |
| Range |
Found in California from Santa Barbara County, where there is a wide zone of intergradation with the Northern Pacific Rattlesnake north to around Morro Bay, east to the central valley and the desert slopes of the transverse and peninsular ranges, and south into the middle of the Baja California peninsula. Ranges north of the transverse ranges into the Mojave Desert in the Antelope Valley and just south of Barstow.
Also found on Santa Cruz and Santa Catalina Islands, both of which are popular vacation destinations.
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| Habitat |
| Found in a wide range of habitats from seaside dunes, to desert scrub, grassy plains, rocky hillsides, chaparral, open woodlands, and agricultural areas. |
| Taxonomic Notes |
The taxonomy of Western Rattlesnakes is controversial and still being studied.
Some researchers still use the species Crotalus viridis and this snake remains Crotalus viridis helleri .
In a 2002 study, Douglas, Douglas, Schuett, Porras, & Holycross
[[2002. Phylogeography of the Western Rattlesnake (Crotalus viridis) Complex, With Emphasis on the Colorado Plateau]. Pp. 11-50. In Biology of the Vipers [Schuett, Höggren, Douglas, and Greene (editors). Eagle Mountain Publishing, Eagle Mountain, Utah]
split C.viridis into 7 distinct species:
Crotalus oreganus oreganus becomes Crotalus oreganus,
Crotalus oreganus helleri becomes Crotalus helleri, and
Crotalus oreganus lutosus becomes Crotalus lutosus.
The common names remain the same.
This taxonomy was accepted by a snake systematist group in 2009 and is already in use by the CNAH. The SSAR will most likely use this taxonomy in its next list.
Some naturalists believe that rattlesnakes on Santa Catalina Island are distinct from those on the mainland and will be recognized as a different subspecies once DNA studies are completed. LA Times Article 11/28/09
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| Conservation Issues (Conservation Status) |
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Taxonomy |
| Family |
Viperidae |
Vipers |
| Genus |
Crotalus |
Rattlesnakes |
| Species |
oreganus |
Western Rattlesnake |
Subspecies
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helleri |
Southern Pacific Rattlesnake |
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Original Description |
Crotalus viridis - Rafinesque, 1818 - Amer. Month. Mag. Crit. Rev., Vol. 4, No. 1, Nov. p. 41
Crotalus viridis helleri - Meek, 1905 - Field Columb. Mus. Publ. Zool., Vol. 7, p. 17
from Original Description Citations for the Reptiles and Amphibians of North America © Ellin Beltz
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Meaning of the Scientific Name |
Crotalus - Greek - krotalon - a rattle - refers to the rattle on the tail
oreganus - belonging to the state of Oregon - referring to the type locality, "banks of Oregon or Columbia River"
helleri - honors Heller, Edmund
from Scientific and Common Names of the Reptiles and Amphibians of North America - Explained © Ellin Beltz
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Alternate Names |
Crotalus viridis helleri
Crotalus helleri
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Related or Similar California Snakes |
C. o. lutosus - Great Basin Rattlesnake
C. o. oreganus - Northern Pacific Rattlesnake
C. ruber - Red Diamond Rattlesnake
C. atrox - Western Diamond-backed Rattlesnake
C. s. scutulatus - Northern Mohave Rattlesnake
C. c. laterorepens - Colorado Desert Sidewinder
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More Information and References |
Natureserve Explorer
California Dept. of Fish and Game
Living With Rattlesnakes
Tucson Herpetological Society: Living With Venomous Reptiles pdf
California Department of Fish and Game: Rattlesnakes in California
University of California: Rattlesnakes Management Guide
San Diego Natural History Museum: Rattlesnakes FAQ
Rattlesnake Bites
California Poison Control System:
Rattlesnake Bites
University of Arizona:
Rattlesnakes
Justin Schwartz' Rattlesnake Bite Story and Pictures
Sean Bush MD: Venom ER - When snakes strike!
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.
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The following status listings come from the Special Animals List which is published several times each year by the California Department of Fish and Game.
This snake is not included on the Special Animals List, which indicates that there are no significant conservation concerns for it in California.
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Organization
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Status Listing
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| U.S. Endangered Species Act (ESA) |
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| California Endangered Species Act (CESA) |
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| California Department of Fish and Game |
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| Bureau of Land Management |
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| USDA Forest Service |
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| Natureserve Global Conservation Status Ranks |
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World Conservation Union - IUCN Red List
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