A widespread Western pit viper. Like all rattlesnakes, they play a critical ecological role controlling rodent populations — and they're NOT aggressive. Most bites occur when people deliberately try to handle, kill, or photograph them.

Also called: Prairie Rattlesnake, Hopi Rattlesnake (southwestern subspecies)

Native status: Native to western US, Canada, and northern Mexico

§ Quick facts

SizeLength 70–135 cm (28–53 in); maximum 165 cm
Weight300–1,200 g
LifespanWild typically 16–20 years; captive 24+
OrderSquamata
FamilyViperidae

§ Encyclopedia

Crotalus oreganus, commonly known as the Western rattlesnake or northern Pacific rattlesnake, is a venomous pit viper species found in western North America from the Baja California Peninsula to the southern interior of British Columbia.

Source: Wikipedia — Crotalus oreganus Licensed under CC BY-SA 4.0

§ Identification

Field marks. Medium-large rattlesnake with greenish-gray to brown background; dark oval or diamond-shaped blotches with pale borders; pale tail with dark crossbands; rattle at tail tip.

Similar species. Eastern and Western Diamondback Rattlesnakes (clearer diamond pattern). Massasauga (smaller, smaller rattle). Pygmy Rattlesnake (much smaller).

Voice. Loud sustained rattling buzz as defensive warning.

§ Diet & behavior

Diet. Small mammals (ground squirrels, rabbits, mice, rats), prairie dogs, small birds, lizards. Ambush hunter.

Behavior. Most widely-distributed rattlesnake in North America. Lives in burrows of prairie dogs, ground squirrels, and other rodents; uses these for hibernation aggregations of dozens to hundreds of individuals from multiple species. Venom is hemotoxic — destroys tissue and disrupts blood clotting. Bites are medically serious; antivenom available and effective when administered promptly. Generally tolerant of human presence; rarely strikes without significant provocation.

§ Range

Western US from Washington to California, east to Idaho

§ Habitat

Rocky slopes, sagebrush, grassland, oak woodland

§ Threats

Persecution, road mortality, "rattlesnake roundups" in some states, habitat loss.

§ Conservation status

According to the IUCN Red List, the western rattlesnake (northern pacific) is currently classified as Least Concern.

§ What helps

Walk away — rattlesnakes WANT distance. Don't kill snakes. Support science-based snake management.

Support our work More ways to help

§ Further reading

§ Sources cited

  • Western Rattlesnake Conservation Project
  • Arizona Game and Fish Department
  • The Orianne Society
  • IUCN Red List 2007