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The Western Rattlesnake (Crotalus viridis ) has one of the
largest home ranges of rattlesnakes in North America. This
rattlesnake or its subspecies can be found in the Canadian
provinces and southward across the central United States
to Mexico. In South Dakota, the subspecies is called the
Prairie Rattlesnake (C. v. viridis ) and found 10-15 miles
east of the Missouri River and western South Dakota, in
the open prairies, haylands, and croplands -- any area with
an abundance of food.
Rattlesnakes are cold-blooded or ectothermic animals. Their
body temperature is influenced more by the temperature at
the grounds surface where they are lying, rather than the
air temperature. High or low temperatures cause the snakes
to seek escape cover or shady areas. Most snakes cannot
survive exposure to direct sunlight with temperatures over
100 degrees F, but rattlesnakes have a greater endurance
to lower or freezing temperatures.
Lethal temperatures for the snakes depend on the time of
exposure. Unlike warm-blooded or endothermic animals, snakes
are unable to produce their own body heat. To maintain a
desirable temperature, snakes must rely the temperature
or warmth of their surroundings. The snake's circulatory/nervous
systems aid in controlling the warming or cooling of their
body.
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