Mountain beavers occur in dense riparian-deciduous and open, brushy stages of most forest types.
Frequent open and intermediate-canopy coverage with a dense understory near water. Deep, friable soils are required for burrowing, along with a cool, moist microclimate. Feed on vegetative parts of plants, mostly thimbleberry, salmonberry, blackberry, dogwood, salal, ferns, lupines, willows, and grasses. Burrows are located in deep soils in dense thickets, preferably near a stream or spring. Line nest with dry vegetation.