Snakes Of The Grand Canyon

Although several reviews and lists of the reptiles and amphibians of the Grand Canyon have been generated, the distributions of many species in the canyon are still poorly understood and several species are commonly misidentified by observers. Since general specimen collecting is not allowed in the Grand Canyon, we sought information from a numerous yet largely untapped resource, visitors and employees. Beginning in 1997, we encouraged the river guides, park staff, and visitors to provide photographic records and localities of the snakes they encountered while in the canyon. To date, this database includes over 280 records of thirteen different species. This database includes records of three species previously unreported from the Canyon—ringnecked snake (Diadophis punctatus), Western diamondback (Crotalus atrox), and Mojave rattlesnake (Crotalus scutulatus)—and new localities of known species.
The data from this study augment information collected in a companion study with scientists from Arizona State University, Grand Canyon National Park, and the senior author. Data from each study confirmed that several snakes are commonly misidentified in the Grand Canyon area, and the combined effort has allowed for a refinement of the distributions of the commonly confused Southwestern speckled rattlesnake (Crotalus mitchelli pyrrhus) and the Grand Canyon rattlesnake (Crotalus viridis abyssus) along the Colorado River. The current distribution of the Grand Canyon rattlesnake extends from Page, Arizona, downstream to

National Canyon (rm 166.5 l). The speckled rattlesnake has been found from 150-mile Canyon (which creates Upset Rapid) downstream through the rest of the canyon onto Lake Mead and throughout the Lower Colorado River Valley. So as far as we know there are 16.5 river miles where the distributions of these two species overlap. The speckled rattlesnake is typically referred to as a rock-dweller; however along the Colorado River in the Grand Canyon, this species can be found in a variety of additional habitats such as at the river's edge, in amongst vegetation on beaches, along the creeks, and in the washes. It appears to inhabit the same niche that the Grand Canyon rattlesnake does in the upper end of the canyon.
Although photographs are not always as perfect as having actual specimens (e.g. some may not be in sharp focus, not close enough, etc., to verify the identification), we have learned a great deal about the snakes in the Grand Canyon from this non-invasive method of documentation. Your interest and support of this project over the last three years has allowed us to learn what we have. We plan to continue to gather information on snakes in the canyon and hope that your interest prevails along with the project.
Nikolle L. Brown, Wildlife Biologist
7779 N. Leonard, Clovis, CA 93611
black-catnik@worldnet.att.net
Cecil Schwalbe, Herpetologist
University of Arizona, Tucson, AZ 85721