Description: This species commonly grows to more than 3.3 feet in length. The maximum recorded size is 4.97 feet. In Montana, specimens occasionally exceed 3.9 feet 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.

Generally, prairie 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 prairie 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 prairie rattlesnake from other rattlesnakes is the presence of two internasals contacting the rostral.

Habitat: Habitat characteristics can vary depending on range. Generally, western rattlesnakes occupy areas with an abundant prey base. They occupy somewhat rocky areas with outcrops serving as den sites. Prairie 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.

Range: Prairie rattlesnakes are found in North America 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 Idaho, most of Montana (where it is one of 10 snake species and the only venomous one), North Dakota, South Dakota, Wyoming, Nebraska, Colorado, Kansas, Oklahoma, Texas, New Mexico, northeastern Arizona, extreme western Iowa, and in Mexico in northern Coahuila and northwestern Chihuahua. Its vertical range is from 330 feet near the Rio Grande to over 9,104 feet in elevation in Wyoming.

Found in these States: AZ | CO | IA | ID | KS | MT | ND | NE | NM | OK | SD | TX | UT | WY

Venom: The prairie rattlesnake is a medium-sized snake so their venom glands are small and can contain only moderate amounts of venom. When it bites the prairie rattlesnake can inject from 20 to 55% of its venom stock in a single bite. But they will sometimes deliver a dry bite, up to 20% of the time, where no venom is injected.

They do produce a potent venom with neurotoxic and hemotoxic properties, which kills the prey and also helps with the digestion by destroying tissue. Some populations of the prairie rattler are thought to possess the infamous "Mojave toxin" like their relative the Mojave rattlesnake (Crotalus scutulatus). So even with their small size, the prairie rattlesnake is capable of delivering a lethal bite to an adult human, although this is rare.

Diet: Prairie 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.[9]

Reproduction: Prairie 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 to 28 cm long, without the need for parental care. In addition, the young 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.

Status: Listed as Least Concern in view of its wide distribution, presumed large population, and because it is unlikely to be declining fast enough to qualify for listing in a more threatened category.

Taxonomy: