Crotalus oreganus, commonly known as the Western rattlesnake or northern Pacific rattlesnake,[4][5] is a venomous pit viper species found in western North America from the Baja California Peninsula to the southern interior of British Columbia.

A large, dark-brown blotch on the snout has a pale border behind it that forms transverse bars on the supraoculars.

There is a dark brown postocular stripe with a white border that extends from the eye to around the angle of the jaw.

[10] It is found in North America from southwestern Canada, through much of the western half of the United States, to the Baja California Peninsula of Mexico.

In Canada, it is found in southern interior of British Columbia and is one of only three remaining rattlesnake species in the country.

Parturition of 1–15 (average 3–8) young usually occurs in August or September, with neonates ranging 19–28 cm.

[14]: 179–181 p. Mating usually takes place in concealed areas, like burrows, crevices of rocks and logs, or dense brush.

The species undertakes seasonal migrations between winter and summer habitats to adjust to prey availability.