Family: Viperidae, Pit Vipers view all from this family
Description 16-64" (40.6-162.6 cm). Size and color vary greatly. Brownish blotches down midline of back, generally edged with dark brown or black and often surrounded by light border; begin as oval, squarish, diamondlike, or hexagonal markings and tend to narrow into inconspicuous crossbands near tail. More than 2 internasal scales touch rostral scale. Scales keeled, in 25-27 rows.
Warning Rattlesnakes, Copperheads, and Cottonmouths belong to a group of snakes known as pit vipers. These dangerous snakes have a heat-sensitive sensory organ on each side of the head that enables them to locate warm-blooded prey and strike accurately, even in the dark. The curved, hollow fangs are normally folded back along the jaw. When a pit viper strikes, the fangs rapidly swing forward and fill with venom as the mouth opens. The venom is a complex mixture of proteins that acts primarily on a victim's blood tissue. If you hear a rattlesnake shaking its rattle, back away. The snake is issuing a warning, and if the warning is ignored it may bite. There are many factors (temperature being the most important) that determine how a snake will react when confronted by a human. Venomous snakes should always be observed from a safe distance. Pit vipers are never safe to handle. Even dead ones can retain some neurological reflexes, and "road kills" have been known to bite. How to avoid and treat snakebites
Subspecies Grand Canyon (C. o. abyssus), reddish above, blotches obscure; Grand Canyon, Arizona.
Arizona Black (C. o. cerberus), dark gray, brown, or almost black above, large dark blotches partially bordered by white scales; Arizona south of the Colorado Plateau, from Hualapai southeastward to Blue Mountains and into extreme w. New Mexico.
Midget Faded (C. o. concolor), pale yellow, blotches obscure or absent; extreme sw. Wyoming, w. Colorado, and e. Utah.
Southern Pacific (C. o. helleri), resembles Arizona Black, diamond-shaped blotches completely bordered by light scales, poorly defined tail rings; San Louis Obispo and Kern counties, California, south to s. Baja California.
Great Basin (C. o. lutosus), light brown or gray above; blotches narrow (roughly equal to interspaces); se. Oregon, s. Idaho, ne. California, Nevada, w. Utah, extreme nw. Arizona.
Northern Pacific (C. o. oreganus), resembles Southern Pacific, blotches oval or hexagonal, well-defined tail rings; sc. British Columbia, Washington, wc. Idaho, Oregon (except se. corner), west of Sierra Nevadas in California south to Kern County.
Breeding Mates March to May and in fall; 4-21 young, 6-12" (15-30 cm) long, are born August to October.
Habitat Brush-covered sand dunes on Pacific coast to timberline in the Rockies and the coniferous forests of the Northwest; rocky outcrops, talus slopes, and stony canyons; sea level to 11,000' (3,350 m).
Range Sc. British Columbia south through Washington, Oregon, and Idaho to Baja California, w. Colorado, sw. Arizona and extreme wc. New Mexico.
Discussion Western counterpart of the Timber and Prairie Rattlesnake (the Western and Prairie were once considered a single species, C. viridis, called the Western Rattlesnake). In northerly areas or at high elevations, large numbers may overwinter together at a common den site. In southerly areas or those lacking large rocky retreats, individuals may seek shelter in mammal burrows. Active April to October over much of range, and becomes crepuscular and nocturnal during hot summer months. Adults prey chiefly on small mammals; young like lizards and mice. Record longevity is 19 1/2 years.
