The Klamath-Siskiyou Mountains are home to a great diversity of animal life. Sixty-nine mammal species and an estimated 392 bird species are known to inhabit the region, as well as an unusually high diversity of butterflies and forest mollusks.
The Salmon River watershed supports healthy populations of deer, elk, black bear and mountain lions. Due to its large expanses of wilderness and rugged mountain terrain, the Salmon River is also home to a number of relatively rare forest carnivores, such as Pacific fishers, pine martens and ringtail cats. The elusive wolverine is also suspected to inhabit these mountains.