The field marks below can help differentiate these two similar species of rattlesnake where their ranges overlap in California. Since both of these species are dangerously venomous, I do not advise handling a snake. Instead, use binoculars, or take a picture with a telephoto lens and then enlarge the picture, to see the field marks. This will be the only way to observe the supraocular scales. |
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LIght Stripe Behind the Eye |
Northern Mohave Rattlesnake -
Crotalus scutulatus scutulatus |
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Western Diamond-backed Rattlesnake - Crotalus atrox |
A light stripe extends from behind the eye diagonally to beyond the end of the jaw. |
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A light stripe extends from behind the eye diagonally to the upper lip in front of the end of the jaw. |
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Number of Scales Between the Supraoculars |
(The supraoculars are the large scales directly above each eye.) |
Northern Mohave Rattlesnake -
Crotalus scutulatus scutulatus |
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Western Diamond-backed Rattlesnake - Crotalus atrox |
There are 2
large scales
between the supraoculars |
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There are 4 or more small scales
between supraoculars. |
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Width of the Rings on the Tail
Color of Ring Next to the Rattle
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Northern Mohave Rattlesnake -
Crotalus scutulatus scutulatus |
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Western Diamond-backed Rattlesnake - Crotalus atrox |
The black rings are narrower than the light rings, and often offset. |
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Broad black and white rings are
fairly equal in width. |
The color of the ring closest to the rattle
is usually White |
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The color of the ring closest to the rattle
is usually Black |
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Rattlesnake References
Robert Powell, Joseph T. Collins, and Errol D. Hooper, Jr.
A Key to Amphibians and Reptiles of the Continental United States and Canada.
© 1998 by the University Press of Kansas.
Chester J. Stojanovich and Margaret A. Parsons. Snakes: Pictorial Key to Venomous Species in United States
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.
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.
Hubbs, Brian R., & Brendan O'Connor. A Guide to the Rattlesnakes and other Venomous Serpents of the United States. Tricolor Books, 2011.
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.
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