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A Guide to the Amphibians
and Reptiles of California


Crotalus oreganus oreganus - Northern Pacific Rattlesnake

(=Crotalus oreganus)


Click on a picture for a larger view





Range in California: Red

Click the map for a guide
to the other subspecies.




observation link



Venomous and Potentially Dangerous!

Adult, Contra Costa County Adult, Fresno County Adult, Yuba County
Adult, Contra Costa County
Adult in basking spot, San Joaquin County Breeding Adults discovered under a piece of tin, San Joaquin County
Adult, Santa Cruz County
Adult, San Joaquin County
Adult, San Joaquin County
Adult, Alameda County
Adult, Napa County
Adult, Del Norte County © Alan Barron
Adult, Mare Island, Solano County Adult, 6,200 ft., Tuolumne County Adult, 5,600 ft., Tuolumne County
Adult, San Joaquin County
© Chad Lane
Greenish adult, Lake County.
© Lawrence Anderson
Adult, Sutter Buttes, Sutter County.
© Jackson Shedd.
Specimen courtesy of Eric Olson.
Adult, Shasta County © Richard Gentile
Adult, Santa Clara County © John Worden Sub-adult, Santa Cruz County.
© Norbert Fanjat
Adult, Santa Clara County
© Leo Gomez
Adult, Fresno County
© Patrick Briggs
Adult in Yosemite National Park
© Kenneth D. Cohn
Adult, 8280 ft., Tulare County.
© Scott Wiley
Intergrade with C. o. helleri , Santa Barbara County © Benjamin German
© Ryan Hunter Adult, Siskiyou County © Doug Jeffries Tail and Rattle
Old rattlesnakes, especially those in captivity such as this one in a museum in Bend, Oregon, often have a very long string of rattles.
Juveniles
Juvenile, San Luis Obispo County Juvenile, Placer County Juvenile, Santa Cruz County Juvenile, Sonoma County
© Roman Duellge
Juvenile, Kings County
Juvenile, San Joaquin County Juvenile, San Benito County Juvenile, Alameda County
     
Tiny juvenile, Mare Island, Solano County      
Breeding Males in Combat
 
Two males in a wrestling match over a female in late April in Santa Clara County. The shot on the far right shows a snake on the ground, probably the female, with one of the males above her. During the action, a third male also entered the scene, which is not shown here. © Holly Lane  
Eating
Adult eating a rodent, Kern County. © Renee Simpson A large adult eating an even larger rabbit in Sonoma County. © Chris Arai
Interesting Pattern or Color Variations
This unusually-patterned snake from coastal dunes in San Luis Obispo County has a mostly patternless body with a pale dorsal stripe (similar to a garter snake) and the usual rings around the tail. © Kevin Crouch Very dark adult from western Kern County © Mike Waters
Oddly-patterned juvenile from western Kern County © Mike Waters

Adult, San Mateo County, ready to shed - showing very little contrast in its pattern. © Melissa Amarello
Adult, 8280 ft., Tulare County.
© Ken D. Wiley
Adult, Kern Plateau, Kern County
© Sam Wilson
 
A patternless green adult from Santa Cruz County © Ben Witzke Patternless adult, Contra Costa County
© Ameet Zaveri
 
Variations in Appearance Near the Southern Range Limit
C. o. oreganus near its southern range limit is variable in appearance, sometimes with markings similar to C. o. lutosus. Identification of rattlesnakes found in this region can be confusing and open to debate. I have received several comments that I might have mis-identified snakes from this region - that they could be intergrades or hybrids, or that the Kern County snake depicted below left is actually C. o. lutosus. However, it is a C. o. oreganus, based on appearance, location, and some preliminary genetics work that has been done in the area. The Inyo county rattlesnake depicted below right from the southern Sierras has been identified by various viewers of the photo as C. o. oreganus or C. o. lutosus, or as a young Panamint Rattlesnake - Crotalus mitchellii stephensi which is what it is.

Rumors of C. oreganus x C. mitchelli stephensi hybrids have not yet been confirmed by genetic analysis. Some of these controversies should be resolved when the results of further studies on these species are published.

According to herpetologist Robert Hansen, who has studied in depth the reptiles and amphibians of the Southern Sierra Nevada Mountains and the surrounding regions: "Among populations of "oreganus" inhabiting arid landscapes near their southern range limits (e.g., southern San Joaquin Valley, Carrizo Plain), there is a tendency toward small size, light ground color, and reduced dorsal blotch size...features that cause these snakes to superficially resemble lutosus."..."The southern extent of the range of lutosus in eastern California (e.g., the Mono/Inyo counties region) has been mapped in reasonable detail, and thus far, there are no known instances where the ranges of oreganus and lutosus come into contact.
However, farther north, where the Sierra Nevada crest is much lower and the potential for populations of oreganus and lutosus to meet is likely greater, careful field studies are lacking. Ultimately, reliance on features of coloration and pattern to distinguish one form from the other in areas of potential contact is not advised."

 
Adult, Greenhorn Mountains, Kern County
Robert Herndon found this adult snake near Three Rivers in Tulare County.
© Robert Herndon
Panamint Rattlesnake - Crotalus mitchellii stephensi, Inyo County © Carl Brune
 
Habitat
Habitat, San Joaquin County Habitat, Alameda County Habitat, Alameda County Habitat, Contra Costa County
Habitat, Alameda County
Habitat, Contra Costa County
Habitat, Yuba County Habitat, Mare Island, Solano County
Habitat, Fresno County
Habitat, Kings County
Chaparral Habitat, Lake County
© Lawrence Anderson
Habitat, Sonoma County
© Roman Duellge
Den site, Contra Costa County
© Erik Grouell
Habitat, Contra Costa County
© Erik Grouell
Habitat, aprox. 3,000 ft. Siskiyou County © Doug Jeffries
Adult, basking at ege of a den (a deep crack in a large boulder) in early March, Kern County
 
Habitat, 5,600 ft., Tuolumne County Habitat, Kern County Habitat, 5,400 ft. Sierra Nevada Mountains, Kern County  
Short Videos and Sounds
A Northern Pacific Rattlesnake crossed a mountain road on a windy spring morning in Contra Costa County then coiled defensively at the edge of the road. Concerned with my presence a few yards away, it is seen here sensing the air with its tongue and rattling its tail, then pausing to watch a bicycle speed down the road, then rattling some more.
A juvenile rattlesnake rattles and crawls off a road in the foothills of Fresno County in early Fall.
A Northern Pacific Rattlesnake rattles its tail. The snake here is seen slowly following a snake hook with curiosity, not aggression. The hook had been used earlier to pick up a breeding pair of snakes, and we decided that this one was probably a male that smelled the scent of the breeding female on the hook.
 
Most rattlesnakes will do exactly what this one did when I encountered it in the late afternoon on a mountain road - turn and crawl quickly away, with a little rattling thrown in as a warning.  Rattlesnakes are often depicted in fiction as aggressors, leaping and striking viciously, often for no reason other than to give the hero an excuse to kill it to prove himself. The truth is that rattlesnakes are almost always defensive, not offensive, when they encounter humans, wanting nothing more than to escape, and the least heroic thing someone can do is to automatically kill them. This video begins with a squirrel's high-pitched alarm call coming from a large group of shrubs in the Sierra Nevada mountains. When I got closer the squirrel ran away and I saw this rattlesnake climbing down a branch then farther back into the bushes. Later, after the camera batteries died, the snake returned and crawled outside the shrubs while the squirrel called and ran around outside the bushes near the snake, but outside of its striking range. A Northern Pacific Rattlesnake in the Sierra Nevada mountains crawls into a crack and shakes its tail.  
 


 
 
Listen to a Northern Pacific Rattlesnake rattling.

 
 
   
  Click on 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.

Description

Venomous
The venom of this snake is potentially dangerous to humans.
Size
Adults 15 - 36 inches long, ( 38 - 91 cm) sometimes up to 48 inches (121 cm) with 60 inches being the longest (151 cm).
Appearance
A heavy-bodied, venomous pit viper, with a thin neck and a large triangular head. Pupils are elliptical. Scales are keeled. Usually with a light stripe extending diagonally from behind the eye to the corner of the mouth.

The ground color is variable, matching the environment - olive-green, gray, brown, golden, reddish brown, yellowish, or tan. Dorsal blotches on the front 2/3 of the body, change to dark bars on the body and dark and light rings on the tail which are well-defined and of uniform width. Young have a bright yellow tail. The underside is pale, sometimes weakly mottled.

Dark brown or black blotched markings, usually with dark edges and light borders, mark the back, with corresponding blotches on the sides. This pattern is brighter on juveniles than on adults.

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. In colder areas, known to den in burrows, caves, and rock crevices, sometimes in large numbers, and sometimes with other snake species.

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 are born August - October.
Range
Found in California from Santa Barbara county, where it intergrades with the Southern Pacific Rattlesnake, east to the Sierras, and north from the coast to the Sierras and west of the Cascades ranges. Ranges north through Oregon, west of the Cascades in Washington and into British Columbia, Canada, and east west-central Idaho.
Habitat
Inhabits rocky hillsides, talus slopes and outcrops, rocky stream courses, rocky areas in grasslands, mixed woodlands, montane forests, pinyon juniper, sagebrush. Sea level to around 11,000 ft.
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 oreganus.

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.
Conservation Issues  (Conservation Status)
None.

Taxonomy
Family Viperidae Vipers
Genus Crotalus Rattlesnakes
Species oreganus Western Rattlesnake
Subspecies


oreganus Northern Pacific Rattlesnake
Original Description
Crotalus viridis - Rafinesque, 1818 - Amer. Month. Mag. Crit. Rev., Vol. 4, No. 1, Nov. p. 41
Crotalus viridis oreganus - Holbrook, 1840 - N. Amer. Herp., Ed. 1, Vol. 4, p. 115, pl. 29 [24 in text]

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
oreganus
- belonging to the state of Oregon - referring to the type locality, "banks of Oregon or Columbia River"

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

Alternate Names
Crotalus viridis oreganus

Crotalus oreganus

Related or Similar California Snakes
C. o. helleri - Southern Pacific Rattlesnake
C. o. lutosus - Great Basin Rattlesnake
C. atrox - Western Diamond-backed Rattlesnake
C. s. scutulatus - Northern Mohave Rattlesnake
C. m. stephensi - Panamint Rattlesnake

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!




Publications


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 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.

Organization
Status Listing
U.S. Endangered Species Act (ESA) None
California Endangered Species Act (CESA) None
California Department of Fish and Game None
Bureau of Land Management None
USDA Forest Service None
Natureserve Global Conservation Status Ranks
World Conservation Union - IUCN Red List





 

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