Prairie Rattlesnake

Appearance

This species commonly grows to more than 100 cm in length. The maximum recorded size is 151.5 cm . In Montana, specimens occasionally exceed 120 centimetres in length; the species reaches its maximum size in this region. One of the most characteristic features is the presence of three or more, usually four, internasal scales.

Identification characteristics will vary depending on which subspecies is encountered. Generally, western rattlesnakes 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.

Naming

Common names for this species include: prairie rattlesnake, western rattlesnake, plains rattlesnake, black rattler, prairie rattler, common rattlesnake, confluent rattlesnake, Great Basin rattlesnake, large prairie rattlesnake, Missouri rattlesnake, rattlesnake of the prairies, spotted rattlesnake, western Pacific Rattlesnake.The ''Crotalus viridis nuntius,'' Hopi rattlesnake ,
inhabits the United States from northeastern and north-central Arizona, from the New Mexico border to Cataract Creek, including the Little Colorado River basin, the southern section of the Apache Indian Reservation, the Hopi Reservation, and the Coconino Plateau from the southern rim of the Grand Canyon to US Highway 66 in the south.

The ''Crotalus viridis viridis,'' prairie rattlesnake , inhabits the North American Great Plains from the Rocky Mountains to 96° W and from southern Canada to extreme northern Mexico, including southwestern Saskatchewan, southeastern Alberta, eastern Washington, Idaho in the Lemhi Valley, Montana east of the higher Rockies, southwestern North Dakota, west, central and extreme southeastern South Dakota, western Iowa, central and western Nebraska, Wyoming except for the Rockies, Colorado, central and western Kansas, Oklahoma, extreme southeastern Utah, northeastern Arizona, New Mexico, western and southwestern Texas, northeastern Sonora, northern Chihuahua, northern Coahuila.

Status

This species is classified as Least Concern on the IUCN Red List of Threatened Species . Species are listed as such due to their wide distribution, presumed large population, or because they are unlikely to be declining fast enough to qualify for listing in a more threatened category. The population trend was stable when assessed in 2006.

Behavior

Western rattlesnakes live on the land, but it can sometimes climb in trees or bushes. Some even rest in crevices or caves. They are typically active diurnally in cooler weather and nocturnally during hot weather . This species complex is equipped with powerful venom, using about 20-55 percent of venom in one bite, and will defend themselves if threatened or injured. As with other rattlesnake species, western rattlesnakes will rapidly vibrate their tails, which produces a unique rasping sound to warn intruders.

The toxin of the Western Rattlesnake is a complexly structured mixture of different proteins with enzymes such as proteases and peptidases found among them. Besides the hemotoxine and its tissue destructive effect, the poison also has neurotoxic properties.

Habitat

Habitat characteristics can vary depending on subspecies and range. Generally, western rattlesnakes occupy areas with an abundant prey base. Many subspecies occupy somewhat rocky areas with outcrops serving as den sites. Western rattlesnakes have also been known to occupy burrows of other animals. They seem to prefer dry areas with moderate vegetation coverage. Vegetation cover will vary depending on region and subspecies.

Reproduction

Western rattlesnakes are viviparous and can produce from one to 25 young per reproduction event. The average number of young ranges from four to 12, but can vary greatly due to availability of food and environmental conditions. Males may compete for females during the breeding season, but Western rattlesnake females may not necessarily breed every year. They give birth in late summer or early fall, being their breed 22-28 cm long, without the need for parental care. In addition, their pups are toxic as soon as they are born. They reach sexual maturity at three years of age. It is also common for females to give birth at communal den sites with the young born between August and October.

Food

Western rattlesnakes, because of their expansive distribution, have a wide array of prey. Generally, this species prefers 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. This is more commonly seen in juvenile snakes.