Description: The color pattern of the typical form, C. o. oreganus, has a dark brown, dark gray, and sometimes black or pale yellowish ground color. This is overlaid dorsally with a series of large dark blotches with uneven white edges. These blotches are also wider than the spaces that separate them. Additionally, there is a lateral series of blotches that are usually darker than the dorsal blotches and clearly visible on all but the darkest specimens. The first rings of the tail are about the same color as the last body blotches, but these become progressively darker; the last two, at the base of the tail, are usually black. The belly is pale yellow, usually with brown spots. A large dark brown blotch on the snout has a pale border behind it that forms transverse bars on the supraoculars. There is a dark brown postocular stripe with a white border that extends from the eye to around the angle of the jaw.
Habitat: Crotalus viridis are found mostly in grasslands and prairies, and in brush. Various subspecies can also be found in woods, forests, caves, rock ledges, and alongside streams. Avoids the desert.
Breeding: Mate between March and May. They have internal fertilization; males have a hemipenis which they use for copulation. Females give birth to between 4-21 live young in late summer or early fall. The babies are able to take care of themselves immediately and require no parental care. They are from 22-28 cm long when born and are already venomous. They reach sexual maturity after three years. Males may compete for females during mating season; however, body size of males does not seem to be a trait that contributes to mating success. In areas where females are scarce, males spend more time searching for females, and are not generally observed fighting over females.
Range: Found in North America over much of the Great Plains, from southern Canada south through the United States to northern Mexico. In Canada it occurs in Alberta and Saskatchewan; in the USA in eastern Idaho, Montana, North Dakota, South Dakota, Wyoming, Nebraska, Colorado, Kansas, Oklahoma, Texas, New Mexico, extreme eastern Arizona; in Mexico in northern Coahuila and northwestern Chihuahua. Its vertical range from 100 m near the Rio Grande River to over 2,775 m elevation in Wyoming
Diet: Eats small mammals, ground nesting birds, amphibians, and reptiles, including sometimes other snakes. They locate their prey by using their tongue to sense in airborn chemicals given off by the prey. Then they rapidly strike out at them, biting them with their fangs, then letting them go quickly. Venom is released from their fangs when the snakes strike. It works to immobilize the prey, which the snake then tracks and eats. The venom also works to destroy tissue and help with the digestion of bulkier prey
Behavior: Crotalus viridis are not aggressive. They usually flee if given the opportunity. They can be found in dense populations in some areas. During winter and in cold areas, Crotalus viridis hibernate in caves or burrows of other animals. If hibernation places are scarce, as many as one hundred snakes may share one den. The snakes may even hibernate with other species. In warm weather, they basks in the sun during the day, but in hot weather they seek shelter during the day and come out to hunt at night.
Conservation Status: This species is classified as Least Concern (LC) on the IUCN Red List of Threatened Species (v3.1, 2001). Species are listed as such due to their wide distribution, presumed large population, or because it is unlikely to be declining fast enough to qualify for listing in a more threatened category. The population trend is stable. Year assessed: 2007.
Additonal Notes: can live up to twenty-one years. 95% of deaths occur during the active season, rather than the winter.
Subspecies (2 in our range):
Prairie Rattlesnake (C.v. viridis) - greenihs or brownish above with well defined brown blotches. Found from extreme western Iowa to the Rockies; southern alberta to northern Mexico. Photo...
Hopi Rattlesnake (C.v. nuntius) - pinkish or reddish-brown with the blotches being well defind. Found in northeastern Arizona. Photo...
