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Aug 172012
western rattlesnake

© Loren Thomas 2003

Description: Western rattlesnakes have large, triangular heads, narrow necks, and dark brown or black blotches on lighter backgrounds. They can be up to 65 inches long. Unless they’re newborn or have been injured, all have rattles at the ends of their short tails. Rattlesnakes kill their prey by injecting venom via two large fangs and then swallowing them whole. Three subspecies (Prairie, Great Basin, and Northern Pacific) live in Idaho. They differ mostly in their color patterns, which typically resemble their environments.

Native habitat: Western rattlesnakes are found throughout Idaho, except at high elevations and in the northern part of the state. They prefer dry, rocky areas with sparse vegetation.

Behavior: Western rattlesnakes eat mostly mice, ground squirrels and rabbits. They are active from March to November, generally hunting throughout the day in moderate temperatures but preferring the earlier and later hours during the warm summer months. They seek their prey in or near tall grass, rodent burrows, rock outcrops, surface objects or in the open, and they take shelter in crevices, caves, mammal burrows, and sometimes dense vegetation.

Managing conflicts: Western rattlesnakes are rarely found in Idaho yards, but homeowners living at the urban-rural interface may occasionally see one. Be aware that well-camouflaged rattlesnakes may be waiting quietly for prey in rock crevices, under logs, in heavy brush, or even in tall grass, so be careful where you put your hands and feet. If you hear or see a rattlesnake, move slowly away from it. Few people are bitten by rattlesnakes in Idaho. Although pets have died, no human fatalities have been recorded. You should consider asking for assistance from a wildlife biologist or pest management professional if rattlesnakes are frequenting your yard. Plan to take steps to reduce your yard’s attractiveness to snakes.

Information courtesy of:

  • University of California IPM Online, Rattlesnakes
  • Idaho Museum of Natural History Digital Atlas, Western Rattlesnake
  • “Idaho’s Amphibians and Reptiles,” Nongame Wildlife Leaflet #7, Idaho Department of Fish and Game
 August 17, 2012