Western Rattlesnake

October 27, 2015
Heidi Rockney and Karen Wu


Western Rattlesnake.

Western Rattlesnake.
Photo: Heidi Rockney

Name: Western rattlesnake (Crotalus oreganus)
Order: Snakes (Squamata)
Family: Vipers and Pit Vipers (Viperidae)

What they look like

  • Western rattlesnakes are medium-sized snakes that are usually around 36 inches long.
  • Most are greenish brown or greenish gray with many dark brown blotches, each surrounded by a lighter color, along their back.
  • Like all rattlesnakes, they have a flat triangular head and a rattle at the end of their tail.

Where they live

  • View a map of where they live.
  • Western rattlesnakes can be found in many drier regions throughout North America, from Southwestern Canada through western United States (including eastern Washington) to northern Mexico.
  • Even though they prefer drier habitats, western rattlesnakes avoid deserts and instead live in prairies, grasslands, brush, and sometimes in woods, forests, along streams, rock ledges, and caves.

What they eat

  • Western rattlesnakes kill and eat small mammals, amphibians, reptiles, and ground nesting birds using venom that is very deadly to such prey.


  • Between August and October, females give live birth to 4 to 21 young.
  • Oftentimes, many females will gather at a single den to give birth.

Cool Biology Facts

  • The “Crotalus” part of their scientific name comes from a Greek word meaning “little bell”, which refers to their rattle.
  • Each time a rattlesnake sheds its skin, a new segment is added to their rattle. 


  • Western rattlesnakes are considered “least concern” due to their large stable populations and large distribution.
  • View their status on the IUCN Red List of Threatened Species
Distribution Map

Map of Western Rattlesnake distribution in Washington state. Learn more on the NatureMapping Foundation website.

Explore more of the Amphibians & Reptiles of Washington or check out All About Amphibians.

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