Crotalus mitchellii
Crotalus mitchellii is a venomous pit viper species in the family Viperidae. The species is native to the Southwestern United States and adjacent northern Mexico. The species was named in honor of Silas Weir Mitchell, an American medical doctor who also studied rattlesnake venoms. Two subspecies are recognized as being valid, including the nominate subspecies described here.
Description
Generally, Crotalus mitchellii does not exceed in total length, with large males measuring between. The race on Isla Ángel de la Guarda is known to become larger, the maximum recorded length for a specimen there being. In contrast, the population on El Muerto Island only reaches a maximum of in length. On the back are about thirty sometimes vague markings often in the form of crossbars. The speckled rattlesnake is sometimes erroneously called the tiger rattlesnake because of these markings. Other times the markings are clearly defined geometric shapes – diamonds, hexagons, hourglasses – which vary in color from snake to snake but are always darker than the ground color. Normally there is a community coloration based on the snakes' specific rock setting. The whole effect: an individual snake looks like it had been formed from granite, a protective coloration it uses with great effect, and that is also quite beautiful when examined, as one might a work of art, against a contrasting background.Geographic distribution
Crotalus mitchellii is found in the southwestern United States and in northwestern Mexico. In the US, its range includes east-central and southern California, southwestern Nevada, extreme southwestern Utah, and western Arizona. In Mexico, it is native in northwestern Sonora and most of Baja California, including Baja California Sur. It also inhabits a number of islands in the Gulf of California, including Angel de la Guarda Island, Carmen, Cerralvo, El Muerto, Espíritu Santo, Monserrate, Piojo, Salsipuedes, and San José, as well as on Santa Margarita Island off the Pacific coast of Baja California Sur.The type locality is listed as "Cape St. Lucas, Lower California".
Habitat
The preferred natural habitat of Crotalus mitchellii is rocky desert and shrubland.Behavior
Crotalus mitchellii is terrestrial, but will sometimes climb into low vegetation.Reproduction
Crotalus mitchellii is ovoviviparous.Subspecies and taxonomy
argued that C. m. angelensis and C. m. muertensis should be given species status, mainly due to differences in body size.More recently, Douglas et al. recognised C.m. stephensi as a full species, and Meik et al. elevated both the southwestern and the Angel de la Guarda speckled rattlesnakes to the state of full species, C. pyrrhus and C. angelensis, whereas the El Muerto Island speckled rattlesnake was considered part of ''C. pyrrhus''