Confusing Species
Although there are no other species of rattlesnake in western Canada, there are several other blotched snakes which are commonly mistaken for rattlesnakes. Gopher Snakes tend to have a more regular checkered pattern to the blotches. Western Hognose Snakes have a distinctly upturned snout and large blotches on the belly. Night Snakes, found in British Columbia, also have vertical pupils but are much smaller and more slender than Western Rattlesnakes. None of these species have the typical triangular head and rattle of a rattlesnake.

Distribution
Western Rattlesnakes are found in southern Saskatchewan, Alberta and interior British Columbia. They are widely distributed in the southern US reaching down into Mexico.

Habitat
The Western Rattlesnake is found in desert, short grass prairie and dry open scrubland. It is often seen near rock piles or boulders in areas with sandy soil but may also be found near farms and fields. This snake may also be found on rocky outcrops and talus slopes and in association with Prairie Dog towns.

Reproduction
Females begin breeding at an age of 6-8 years and probably do not breed every year. They are live bearing and produce 4-21 young up to 30 cm long. Young are born in late summer or fall.

Natural history
Rattlesnakes have heat sensing facial pits which allow them to locate warm blooded prey such as small mammals and birds. Farmers value them in reducing pests. They also eat reptiles and amphibians. They often hibernate communally in rock crevices or caves or individually in mammal burrows. In spring they may be seen basking at the entrance to a communal hibernaculum. They are an aggressive snake and when disturbed will coil, vibrate the rattle and strike. Although bites are rarely fatal Western Rattlesnakes are venomous and should be treated with caution.

Conservation Concerns
Their communal denning habit makes this snake particularly vulnerable to persecution by people.