Prairie rattlesnakes are venomous pit vipers native to western North America. These snakes are usually lightly colored in hues of brown. Patches of dark brown are often distributed in a dorsal pattern. A color band may be seen at the back of the eye. The western rattlesnake group carries the distinctive triangle-shaped head and pit sensory organs on either side of the head. A key characteristic that can help differentiate a western rattlesnake from other rattlesnakes is the presence of two internasals contacting the rostral.
Prairie rattlesnakes are found over much of the Great Plains, the eastern foothills and some intermontane valleys of the Rocky Mountains, from southwestern Canada through the United States to northern Mexico. In Canada, they occur in Alberta and Saskatchewan; in the US in eastern Oregon, eastern Washington, southern Idaho, most of Montana, North Dakota, South Dakota, Wyoming, Nebraska, Colorado, Kansas, Oklahoma, Texas, New Mexico, extreme eastern Arizona, extreme western Iowa, and in Mexico in northern Coahuila and northwestern Chihuahua. Prairie rattlesnakes inhabit forest, shrubland, grassland and desert areas. They generally occupy areas with an abundant prey base. Many subspecies occupy somewhat rocky areas with outcrops serving as den sites. Prairie rattlesnakes seem to prefer dry areas with moderate vegetation coverage.
Prairie rattlesnakes live on the land, but they can sometimes climb in trees or bushes. Some even rest in crevices or caves and may occupy burrows of other animals. They are typically active diurnally in cooler weather and nocturnally during hot weather. Prairie rattlesnakes have poor eyesight and in order to find prey, they use their heat-sensitive pits or their forked tongue that picks up airborne scents. These snakes generally live alone but hibernate communally during cold winter months. They are not considered to be very aggressive but will defend themselves if threatened or injured. As with other rattlesnake species, Prairie rattlesnakes will rapidly vibrate their tails, which produces a unique rasping sound to warn intruders.
Prairie rattlesnakes are carnivores and prefer to prey on small mammals, such as ground squirrels, ground nesting birds, mice, rats, small rabbits, and prairie dogs. They will occasionally feed on amphibians and reptiles, and sometimes even other snakes.
Prairie rattlesnakes are viviparous reptiles which means that they give birth to live young. During the mating season, males may compete for females but females may not necessarily breed every year. Females give birth from 1 to 25 young, usually in late summer or early fall. The young are born fully developed and are 22-28 cm long. They do need parental care and reach reproductive maturity at three years of age.
There are no major threats to Prairie rattlesnakes at present. However, locally they may suffer from habitat loss for agricultural uses, human persecution, and road mortality.
According to IUCN, the Prairie rattlesnake is locally common and widespread throughout its range but no overall population estimate is available. Currently, this species is classified as Least Concern (LC) on the IUCN Red List and its numbers today are stable.
Prairie rattlesnakes are important predators of many small rodents, such as rats and mice, which make a big portion of their diet and thus control their populations.