Crotalus oreganus helleri
|Crotalus oreganus helleri|
C. o. helleri
|Crotalus oreganus helleri|
Adults are 24-55 inches (61–139 cm) in length.
The color pattern consists of a pale brown, gray-brown, or yellowish brown ground color overlaid with a series of large, dark brown dorsal blotches that may or may not have pale centers. The blotches are more diamond shaped, as opposed to those of C. o. oreganus that are more hexagonal, and are bordered by light scales. The tail rings are not clearly defined. In juveniles, the end of the tail is bright orange, but this turns to brown as the snakes mature. In adults, the base of the tail and the first segment of the rattle are brown. The postocular stripe is moderately to very clearly defined. In juveniles, this stripe is bordered above by a pale stripe, but as the snakes mature this turns to drab yellow or brown. A conspicuous pale crossbar is sometimes present across the supraoculars, after which the head is a uniform dark color. In some older snakes the head is mostly dark with almost no trace of the supraorbital crossbar, or none at all.
Crotalus oreganus helleri has a highly toxic venom that is much like Mojave toxin in the way it attacks nerve endings. It also contains myotoxins (toxic to body muscles) and hemotoxins (toxic to the blood), so it can easily give a fatal bite. The venom from this snake also requires a much higher dose of Crotalidae polyvalent immune fab ("Crofab"), an antivenom used to treat the bite of North American pit vipers, than the venoms of other rattlesnakes.
This snake is found in the United States in southern California, and in Mexico in northern Baja California, west of the desert. In the north it is found from the counties of San Luis Obispo and Kern, and south through the counties of Santa Barbara, Ventura, Los Angeles (including Santa Catalina Island and the foothills.), southwestern San Bernardino, Orange, western Riverside, San Diego and extreme western Imperial. From there its range extends south through Baja California to lat. 28° 30' North. According to Klauber (1956), the type locality is "San Jose, Lower California" [San José, lat. 31° N, Baja California (state), Mexico].
- McDiarmid RW, Campbell JA, Touré T (1999). Snake Species of the World: A Taxonomic and Geographic Reference, Volume 1. Washington, District of Columbia: Herpetologists' League. 511 pp. ISBN 1-893777-00-6 (series). ISBN 1-893777-01-4 (volume).
- "Crotalus oreganus ". The Reptile Database. www.reptile-database.org.
- "Crotalus oreganus helleri ". Integrated Taxonomic Information System. Retrieved 28 November 2006.
- Wright AH, Wright AA (1957). Handbook of Snakes of the United States and Canada. Ithaca and London: Comstock Publishing Associates, a division of Cornell University Press. (7th printing, 1985). 1,105 pp. (in two volumes). ISBN 0-8014-0463-0. (Crotalus viridis helleri, pp. 1014-1018, Figure 290 + Map 67 on p. 951).
- Beltz, Ellin (2006). Scientific and Common Names of the Reptiles and Amphibians of North America – Explained. ebeltz.net/herps/biogappx/html.
- Beolens, Bo; Watkins, Michael; Grayson, Michael (2011). The Eponym Dictionary of Reptiles. Baltimore: Johns Hopkins University Press. xiii + 296 pp. ISBN 978-1-4214-0135-5. (Crotalus oreganus helleri, p. 120).
- Campbell JA, Lamar WW (2004). The Venomous Reptiles of the Western Hemisphere. 2 volumes. Ithaca and London: Comstock Publishing Associates. 870 pp., 1500 plates. ISBN 0-8014-4141-2.
- Behler JL, King FW (1979). The Audubon Society Field Guide to North American Reptiles and Amphibians. New York: Alfred A. Knopf. 743 pp. LCCCN 79-2217. ISBN 0-394-50824-6. (Crotalus viridis helleri, pp. 694-695 + Plate 627).
- http://www.savagelabs.com/Products/CroFab/Home/crofab_frame.htm Link to PDF for full prescribing information, retrieved 11/11/12
- Klauber LM (1997). Rattlesnakes: Their Habitats, Life Histories, and Influence on Mankind. Second Edition. First published in 1956, 1972. Berkeley, California: University of California Press. 1,476 pp. (in two volumes). ISBN 0-520-21056-5.
- Ashton KG, de Queiroz A (2001). "Molecular systematics of the western rattlesnake, Crotalus viridis (Viperidae), with comments on the utility of the d-loop in phylogenetic studies of snakes". Molecular Phylogenetics and Evolution 21 (2): 176–189. PDF at CNAH. Accessed 12 December 2007.
- Hubbs B, O'Connor B (2012). A Guide to the Rattlesnakes and other Venomous Serpents of the United States. Tempe, Arizona: Tricolor Books 129 pp. ISBN 978-0-9754641-3-7. (Crotalus oreganus helleri, pp. 25–27).
- Meek SE (1905). "An Annotated list of a Collection of Reptiles from Southern California and Northern Lower California". Field Columbian Museum Publication 104. Fieldiana Zoology 7 (1): 1–19. ("Crotalus helleri sp. nov.", pp. 17–18 & Plate II).