Western Rattlesnake
Crotalus oreganus
A widespread pit viper of the western United States and Canada, recognized by its dark blotches and rattling tail.
- Venomous?
- Venomous
- Adult length
- 0.9-1.5 m (3-5 ft)
- Range
- Western United States and southwestern Canada
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Overview
The Western Rattlesnake is a broadly distributed pit viper occupying a wide range of habitats across the western United States and into southwestern Canada. It is one of the northernmost-ranging rattlesnake species, tolerating cooler climates than many relatives.
As a pit viper it uses heat-sensing pits to locate warm-blooded prey, and its keratin rattle serves as an audible warning to potential threats.
How to identify it
- Background color ranges from olive, brown, to gray with dark brown or black blotches down the back
- Blotches often become banded near the tail
- Broad, triangular head distinct from a narrower neck
- Heat-sensing pit between eye and nostril
- Vertically elliptical pupils
- Keratin rattle segments at tail tip
- Distinguished from gopher snakes by the rattle, triangular head, and pit organs
Habitat & range
Occupies a wide variety of habitats from sagebrush plains and grasslands to rocky foothills, forests, and coastal ranges across the western US and southwestern Canada, from sea level to high elevations.
Behavior, diet & reproduction
Active by day in cooler months and nocturnal or crepuscular during hot summer months. Feeds on small mammals, birds, and occasionally lizards, ambushing prey with a venomous strike. Gives live birth (viviparous) to litters typically in late summer or fall. Uses its rattle as a warning display when threatened.
Frequently asked questions
How dangerous is the Western Rattlesnake?
It is venomous and can deliver a medically significant bite, though it generally avoids confrontation and warns with its rattle.
Where does it live?
It ranges across much of the western United States and into southwestern Canada in varied habitats.
How can I identify it?
Look for dark blotches on an olive-to-brown body, a triangular head, and a segmented rattle.
Does it give birth to live young?
Yes, like other pit vipers it is viviparous, bearing live young rather than laying eggs.
Western Rattlesnake guides
In-depth guides for identifying and understanding Western Rattlesnake.
Western Rattlesnake identified by the community
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