General Distribution
This common snake ranges widely in California including Santa Catalina Island. It is
absent only from true desert regions and from large tracts in the Central Valley where irrigated
agriculture has eliminated habitat. Found in virtually all habitats, except desert. Elevation sea
level to 3350 m (11,000 ft). Habitat Requirements
When inactive, western rattlesnakes seek cover in crevices in rock outcrops,
under surface objects, beneath dense vegetation, and in mammal burrows. At high elevations
rattlesnakes hibernate for up to several months, usually in crevices in rocky accumulations. Reproduction
Courtship and mating occur after emergence from winter inactivity (March
to May). Live young are born in the fall. Litter sizes range from 1 to 25 but 3 to 12 are most
common. Daily/Seasonal Activity
Mostly nocturnal and crepuscular, rattlesnakes may be active whenever
temperatures are favorable. At high elevations in the Sierra activity is almost exclusively
diurnal. Periods of inactivity during cool weather occur at all localities. Diet and Foraging
Western rattlesnakes forage in or near brushy areas, rock outcrops, mammal
burrows, around and under surface objects, and in the open. Adult rattlesnakes take primarily
rodents, especially ground squirrels. A variety of rodents, rabbits, birds, and even carrion are
also taken (Cunningham 1959, Stebbins 1972 Diller 1981, Lillywhite 1982). Juvenile snakes
take mostiy lizards, especially western fence lizards and side-blotched lizards. Young rodents
are also taken. Prey is subdued largely by poisonous venom produced in modified salivary
glands, and delivered by long, hollow fangs. Territoriality/Home Range
Fitch and Glading (1947) estimated an average home range size for the
western rattlesnake in the Sierra foothills to be about 1.2 ha (3 ac). Most individuals move
over an area of less than 3 m (10 ft) during a day.
The nature of territoriality, if it exists at all in this species, is not well understood.
Combat between males is common, especially during the breeding season (Klauber 1972). Predator-Prey Relations
Rattlesnakes are taken by mammals, predatory birds, and other snakes. An
interesting defensive behavior is exhibited by rattlesnakes when in the presence of
kingsnakes (Carpenter and Gillingham 1975). The behavior involves the raising of parts of
the body in loops above the head, supposedly to fend off direct attacks from kingsnakes. Literature Cited
Carpenter, C. C., and J. C. Gillingham. 1975. Postural responses to kingsnakes by
crotaline snakes. Herpetologica 31:293-302.
Cunningham, J. D. 1959. Reproduction and food of some California snakes.
Herpetologica 15:17-19.
Diller, L. V. 1981. Comparative ecology of Great Basin rattlesnakes (Crotalus viridis
lutosus) and Great Basin gopher snakes (Pituophis melanoleucus deserticola) and their
impact on small mammal populations in the Snake River Birds of Prey Natural Area.
Ph.D. Disser. Univ. Idaho, Moscow. 89pp.
Fitch, H. S., and B. Glading. 1947. A study of a rattlesnake population. Calif. Fish and
Game 33:103-123.
Klauber, L. M. 1972. Rattlesnakes: their habits, life histories, and influence on mankind.
2nd ed. Univ. California Press, Berkeley. 1533pp.
Lillywhite, H. B. 1982. Cannibalistic carrion ingestion by the rattlesnake, Crotalus viridis.
J. Herpetol. 16:95.
Parker, W. S., and W. S. Brown. 1973. Species composition and population changes in
two complexes of snake hibernacula in northern Utah. Herpetologica 29:319-326.
Stebbins, R. C. 1954. Amphibians and reptiles of western North America. McGraw-Hill,
New York. 536pp.
Stebbins, R. C. 1972. California amphibians and reptiles. Univ. California Press,
Berkeley. 152pp.
Information gathered from California DFG - California Interagency Wildlife Task Group
