The sidewinder is a small rattlesnake from
the southwest range of the United States and
the northwest of Mexico.
Hallowell was the first to describe the species
in 1854 as Crotalus cerastes (58.7 cm).
In 1944 Klauber described the subspecies
laterorepens (62.8 cm) and in 1953 Savage and
Cliff described the subspecies cercobombus
The habitats of Crotalus cerastes are the sandy deserts with little or no vegetation and sometimes rocky hills. What little vagitation there is consists usually of creosote bush, mesquite, paloverde and various cati. Its habitats extend in altitude from well below sea level to heights of about 1800 meters.
The difference between the three subspecies (aside from geographical variations) is primarily their size, with C.c.laterorepens being the largest of the three. It is generally believed that this is the only species of Crotalus in North America with females larger then males (which are seldom larger then 60 cm), but this may not be true. Stephen M. Secor, who made an extansive study of this snake in the Mojave Desert, has never noticed any difference in size between males and females.
All three sidewinders have the characteristic elevated scales, or horns, above the eyes. This makes it the only Crotalus species in the southwestern United States that has these hornlike projections over the eyes. It is thought that these horns protect the eyes when digging in the loose sand. The color of the three species varies from yellow, light brown to grey. The belly is normally of a creamy white color. All three sidewinders have 28-45 red-brown spots along the length of their back. Along the length of the back are 141-146 scales.
The species is composed of three poorly defined sub-species:
Crotalus cerastes cerastes, (Hallowell, 1854), the Mojave Desert sidewinder, has the proximal rattle-matrix lobe brown, usually 141 or fewer ventrals in males and 141 or fewer in females, 22 subcaudals in males, 17 or more in females, and 21 scale rows at mid-body.
It is restricted to the Mojave Desert of California (Mono, Inyo, Kern, Los Angeles and San Bernardino counties) and adjacent Mohave County, Arizona, southern Nevada (Esmeralde, Ivye, Lincoln and Clark counties), and south-western Utah (Washington County).
C. c. laterorepens, (Klauber 1944), the Colorado Desert sidewinder, has the proximal rattle-matrix lobe black, usually 124 or more ventrals in males and 146 or more in females, 21-22 subcaudals in males and 17 in females, and 23 scale rows at mid-body. This race ranges in the Colorado Desert from south-eastern California (Riverside, San Diego and Imperial counties) and south-western Yuma County, Arizona, south in Mexico to Baja California and the panhandle of Sonora.
C. c. cercobombus, (Savage and Cliff, 1953), the Sonoran sidewinder, has a black proximal rattle-matrix lobe, usually 141 or fewer ventrals in males, 145 or fewer in females, 20 subcaudals in males, 16 in females, and 21 midbody scale rows. It is found from south-central Arizona (eastern Yuma, Mari-copa, Pinal and Pima counties) southward to western Sonora and Isla Tiburn, Mexico
*Carl H. Ernst, Venomous Reptiles Of North America
This snake is famous for its method of moving across the loose sand. It moves in S- or J-shaped curves by throwing a loop of the bodyin front of the head and then pulling the rest of the body forward.
This method,called "sidewinding", leaves a distinctive track in the sand. No more then two parts of the body at any one time while sidewinding, come into contact with the hot sand. Sidewinding makes the snake move forward in a diagonal direction. C. cerastes is capable of performing all four typical methods of crawling.
It appears to use sidewinding only to get around on loose sand or when it needs to move fast in case of danger.