Western Rattlesnake (specifically Northern Pacific Rattlesnake)
Crotalus oreganus • Order: Squamata, Suborder: Serpentes, Family: Viperidae, Subfamily: Crotalinae, Genus: Crotalus, Species: Crotalus oreganus
Western North America, ranging from British Columbia, Canada, south through Washington, Oregon, and California, and east into Idaho, Nevada, and Utah.
Look up Western Rattlesnake (specifically Northern Pacific Rattlesnake) in the Snake Encyclopedia →Venomous Status
Venomous; Solenoglyphous (front-fanged with long, retractable hollow fangs).
Danger Level
Extremely Dangerous; a bite is a life-threatening medical emergency. While rarely fatal with prompt treatment, it can cause severe permanent tissue damage.
Family
Order: Squamata, Suborder: Serpentes, Family: Viperidae, Subfamily: Crotalinae, Genus: Crotalus, Species: Crotalus oreganus
Conservation
IUCN Status: Least Concern. However, they face threats from habitat loss, road mortality, and intentional killing by humans.
Physical Description
Stout body with heavily keeled scales. Coloration is olive-brown to grayish with a series of large, dark, light-edged dorsal blotches. Distinct triangular head, heat-sensing pits between eyes and nostrils, and a rattle at the end of the tail.
Size & Dimensions
Specimen appears to be an adult approximately 60-90 cm. Typical range for the species is 60-120 cm, with rare individuals reaching 150 cm.
Habitat
Extremely versatile, found in grasslands, brush, woodlands, and rocky hillsides. Often found near outcrops or human structures providing cover. Elevation range from sea level to over 3,000 meters.
Behavior & Temperament
Generally shy and reclusive, preferring to remain camouflaged or retreat. If cornered, it will coil, rattle loudly, and strike defensively. Activity is diurnal in spring/fall and crepuscular or nocturnal in hot summer months.
Diet & Feeding
Active and ambush predator; feeds primarily on small mammals (mice, squirrels, rabbits), birds, and occasionally lizards. Uses venom to immobilize prey before swallowing.
Reproduction
Viviparous (gives birth to live young). Litters typically range from 4 to 21 young, born in late summer or early fall. Females may only breed every 2-3 years depending on food availability.
Venom Profile
Primarily hemotoxic and cytotoxic, causing tissue damage, swelling, and blood clotting interference. Some populations may possess neurotoxic components.
Look-alikes
Commonly confused with Gopher Snakes (Pituophis catenifer), which mimic the rattle sound by vibrating their tail in dry leaves. Gopher snakes have round pupils and lack the triangular head and pits.
Conservation Status
IUCN Status: Least Concern. However, they face threats from habitat loss, road mortality, and intentional killing by humans.
Cultural Significance
A keystone predator that controls rodent populations. Culturally significant in many Indigenous North American traditions and a well-known symbol of the American West.
Notable Features
Possesses a highly evolved tail rattle made of keratin segments and specialized heat-sensing loreal pits that allow the snake to 'see' the thermal signatures of warm-blooded prey in total darkness.