Western Rattlesnake (likely Great Basin or Northern Pacific subspecies)
Crotalus oreganus • Order: Squamata, Suborder: Serpentes, Family: Viperidae, Subfamily: Crotalinae, Genus: Crotalus, Species: C. oreganus
Western North America, ranging from British Columbia, Canada, south through the Western United States to Baja California, Mexico.
Look up Western Rattlesnake (likely Great Basin or Northern Pacific subspecies) in the Snake Encyclopedia →Venomous Status
Venomous (Solenoglyphous fangs)
Danger Level
Extremely Dangerous; bites are medically significant emergencies that can result in permanent tissue damage or death if untreated.
Family
Order: Squamata, Suborder: Serpentes, Family: Viperidae, Subfamily: Crotalinae, Genus: Crotalus, Species: C. oreganus
Conservation
Least Concern (IUCN), though local populations face threats from habitat loss and intentional killing.
Physical Description
Heavy-bodied with a triangular head, vertical pupils, and heat-sensing pits. Features a series of dark, rounded blotches with light borders on a tan or greyish-brown background. Tail ends in a keratinous rattle. Scales are heavily keeled.
Size & Dimensions
Specimen appears to be an adult, approximately 30-40 inches (76-102 cm). Species typically range from 24 to 55 inches (61-140 cm).
Habitat
Highly adaptable, found in grasslands, brushlands, rocky hillsides, and coniferous forests from sea level to over 8,000 feet. Prefers rocky outcrops for denning.
Behavior & Temperament
Generally prefers to avoid conflict; will rattle as a defensive warning if threatened. Primarily crepuscular or nocturnal during hot summer months, but diurnal in milder weather.
Diet & Feeding
Active forager and ambush predator; feeds primarily on small mammals (mice, ground squirrels), birds, and occasionally lizards. Uses venom to immobilize and predigest prey.
Reproduction
Viviparous (gives birth to live young); typical litter size is 4-21 young born in late summer or early fall. Females may breed only every 2-3 years.
Venom Profile
Complex mixture including hemotoxins, cytotoxins, and in some populations (e.g., C. o. helleri), neurotoxins. It causes tissue damage, swelling, and blood clotting issues.
Look-alikes
Gopher Snakes (Pituophis catenifer) look similar but lack rattles, have round pupils, and a narrower head. Other Crotalus species like C. viridis are closely related and difficult to distinguish without locality data.
Conservation Status
Least Concern (IUCN), though local populations face threats from habitat loss and intentional killing.
Cultural Significance
Significant in various Indigenous American cultures as symbols of power or transformation. Ecologically vital for controlling rodent populations.
Notable Features
Equipped with sophisticated infrared-sensing loreal pits located between the eyes and nostrils, allowing them to hunt warm-blooded prey in total darkness.