Northern Pacific Rattlesnake

Crotalus oreganus oreganus

Summary 4

Crotalus oreganus is a venomous pit viper species found in North America in the western United States, parts of British Columbia, and northwestern Mexico. Seven subspecies are currently recognized, including the nominate subspecies described here.
This species, in its various forms, shows considerable ontogenetic variation. Juveniles usually have more or less distinct patterns, but these fade as the animals mature. The color of the iris often matches the ground color, which may be bronze, gold, or different shades of tan, pink, or gray.[3]
It is found in North America from southwestern Canada, through much of the western half of the United States, and south into northern Mexico. In Canada, it is found in southern British Columbia. In the US, it occurs in Washington, Oregon, western and southern Idaho, California, Nevada, Utah, Arizona, and likely west-central New Mexico. In northern Mexico, it is found in western Baja California and the extreme north of Baja California Sur, from sea level to an altitude of 2,500 m (8,200 ft).[3]

This species also reportedly occurs on six different islands.
Using its heat-sensing facial pits to locate prey, C. oreganus eats birds, bird eggs, and small mammals, from mice up to and including rabbits. It also eats small reptiles and amphibians. The juveniles eat insects.[8]
Sexually mature females bear live young in broods of as many as 25.[8]

Crotalus oreganus helleri has a highly toxic venom that is much like mojave toxin in the way it attacks nerve endings. It also contains myotoxins and hemotoxins it can easily give a fatal bite.[8] The venom from this snake also requires a much higher dose of Crofab, an antivenin used to treat the bite of North American pit-vipers.[9]

Sources and Credits

  1. (c) Ken-ichi Ueda, some rights reserved (CC BY),
  2. (c) Gary Nafis, all rights reserved, uploaded by nataliemarisa,
  3. (c) Gary Nafis, all rights reserved, uploaded by nataliemarisa,
  4. Adapted by nataliemarisa from a work by (c) Wikipedia, some rights reserved (CC BY-SA),

More Info

Range Map

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Taxa reptile
Endangered status least concern