Fauna
Reptile

Western Rattlesnake

Crotalus oreganus

Also known as Northern Pacific Rattlesnake, Pacific Rattlesnake

Western rattlesnakes are adaptable pit vipers that rely on heat-sensing facial pits and specialized tail rattles to navigate their environment and deter threats. They spend cold winters coiled together in communal hibernacula before dispersing into grasslands, forests, and rocky hillsides for spring and summer hunting. Ambush predators by nature, these pit vipers play a crucial role in controlling rodent populations across western North America.

VenomousReptilePredator
Western Rattlesnake reference1 / 7
Connor Long / CC BY-SA 4.0 · cc-by-sa
—observations
—countries
—peak records
Least ConcernConservation statusIUCN Red List categoriesLCNTVUENCREWEXLeast ConcernRed List categories, explained →
Key facts
Diet & preyMice, Ground Squirrels, Lizards
Predators
  • Red-tailed Hawk
  • California Kingsnake
  • Coyote
ThreatsHabitat fragmentation, human persecution, road mortality
HabitatsGrasslands, shrublands, dry forests, rocky slopes
Life span15–20 years in the wild
Classification
  1. FamilyViperidae
  2. GenusCrotalus
  3. SpeciesCrotalus oreganus
Range & activity
Native
Safe observation
Interaction riskVery high
  1. Low
  2. Moderate
  3. High
  4. Very high
Why interaction risk is very high
Delivers a dangerous venomous bite if cornered or stepped on; maintain a safe distance and watch where you step.
Why it is dangerous
Possesses hemotoxic venom that causes rapid tissue breakdown, intense pain, severe swelling, and systemic medical complications if left untreated.
How to recognize a risky encounter
Look for a triangular head, facial pits between eyes and nostrils, dark blotches along the back, and a segment rattle at the tail tip.
What to do
Never attempt to handle, poke, or move a rattlesnake; step back at least two meters and grant it a clear route to retreat.
Responsible observation
  • Watch Your Step: Look carefully before stepping over logs, rocks, or into dense brush in snake country.
  • Give Space: Back away slowly if you hear a rattle or spot a snake coiled in a defensive posture.
  • Keep Pets Leashed: Dogs are frequently bitten when investigating off-trail vegetation.
Related species
Keep collecting in Fauna

Found in Collections

Ecosystem chain Pro

Desert Sands

Western Rattlesnake is found in this collection. Identify it in Fauna to fill this slot and continue your progress.

Unlock to track progress

Continue in the app
Help improve the field guideSomething wrong?

Report a name, category, or profile issue for review.

Checking your Fauna account…