 The Adams River valley supports large populations of mule deer , with smaller herds of white @-@ tail deer . Black bears are common in the watershed . The bear population grows substantially during the fall as they gather from adjacent valleys to feed on the spawning salmon . In the upper river valley , moose are common , and the headwaters of the river contain grizzly bear habitat . Several species of aquatic mammals are found on the river , including beaver , mink , and river otter . 
