Western Rattlesnake

BEN PIERCE/CHRONICLE A rattlesnake shakes its rattle in Bear Trap Canyon Trail long the Madison River in southwest Montana.

The western rattlesnake is the only poisonous snake species found in the Rocky Mountain region. The western rattler has retractable fangs that deliver blood-altering venom. Bites are typically painful, but rarely fatal.

Almost universally feared, the western rattler will flee from footsteps and uses its rattle to give warning. When agitated, the rattler will hold its ground and strike if threatened.

Western rattlesnakes locate prey using heat sensors and feed primarily on small rodents and rabbits. They are most active in Montana from April through October. In the winter, western rattlers den communally, sometimes with bull snakes.

Western rattlesnakes are most often found in grasslands, sagebrush, and rocky woods and in canyons. Adult snakes are typically four feet in length with a wide, triangular head. Dark brown markings line the back of the western rattler. The markings turn to ringed bands near the tail.

If you run into a western rattlesnake on the trail, the best response is to freeze your position and allow the snake to retreat.

In the unlikely event of snakebite, remain calm and seek medical attention quickly. As much as possible avoid moving the victim, as movement may spread the venom. Keep the wounded area below heart level and keep the victim warm and calm. If possible, try to identify the snake so the proper antivenin can be administered.