Description
A large (adults usually 75-162 cm), robust, tan, pink, or reddish snake with a series of large diamond-shaped markings (sometimes indistinct) on the back and a horny button or rattle on the end of the tail; tail has alternating broad black and white rings; first pair of lower labials usually is divided transversely; dorsal scales are keeled, in 29 rows at mid-body; young initially are dark gray, changing to reddish brown in the northern part of the range (Stebbins 1985). See Campbell and Lamar (1989) for many further details.
Diagnostic Characteristics
Differs from the western diamondback rattlesnake (CROTALUS ATROX) in generally being more reddish (vs. pale gray-brown), lacking conspicuous dark dots in the body blotches, and in having the first pair of lower labials usually divided transversely. Differs from the western rattlesnake (CROTALUS VIRIDIS) in having usually only two internasals in contact with the rostral and in having broader black rings on the tail. Differs from the speckled rattlesnake (CROTALUS MITCHELLII) in having conspicuous tail rings, lacking conspicuous dark speckling on the ground color, not having the prenasals separated from the rostral by a series of small scales, and lacking pits, furrows, or irregular outer edges on the supraoculars. Differs from the Baja California rattlesnake (CROTALUS ENYO) in lacking supraoculars that are inclined considerably upward toward the lateral side of the head, lacking knobby scales in the frontal region, and in having a tail that is conspicuously banded with dark and light rings. Differs from the Mojave rattlesnake (CROTALUS SCUTULATUS) in being generally reddish or tan (vs. gray to olive or brown), having broader dark tail rings, and lacking enlarged scales between the supraoculars. See Campbell and Lamar (1989) for further details.
Habitat
Habitats are varied and include rocky areas of tropical deciduous forest, ocean shores, desertscrub, thornscrub, open chaparral, mesquite/cactus, and pine-oak woodland, sometimes also dunes, grassland, and cultivated areas between rock outcrops (Grismer 2002, Stebbins 2003, Campbell and Lamar 2004). In southern California, this snake is most common in the western foothills of the Coast Ranges and in dry rocky inland valleys (Ernst 1992, Ernst and Ernst 2003, based on Klauber's studies in San Diego County); it often inhabits areas of granite rock outcroppings, especially in winter (Armstrong and Murphy 1979). In southern Baja California, it is most common in heavy brush where rocks and rocky outcrops are prevalent, but it also occurs in desert and open arid plains (Armstrong and Murphy 1979). This terrestrial snake commonly climbs into low vegetation. Refuges include rock crevices, animal burrows, brush piles, surface debris, or similar sites.
Ecology
May congregate at winter den sites.
Reproduction
Mating has been observed mainly in spring. Viviparous. Bears 3-20 (average around 8-10) young during the summer (August-September).