There the material is cut into short sections at the burrow entrance and carried into the burrow to be eaten or stored. Animals may eat vegetation outside of the burrow, but most often consume it in feeding chambers which are adjacent to the nest. While mountain beaver gather much of the vegetation in their vicinity, there appears to be a decided preference for certain types of plants including shrubs and smaller trees. Some of their preferred foods include species that are unpalatable or toxic to other mammals such as bracken fern, sword fern, nettles, thistles, corn lily, salal, foxglove, larkspur, and skunk cabbage. This gives the mountain beaver a largely uncontested food niche.
Mountain beaver require large amounts of succulent vegetation for survival.
Distribution limits are associated with rainfall and edaphic conditions that promote succulent vegetation and high humidity within burrows. Studies suggest that the most important factors in habitat use are a cool thermal regime, adequate soil drainage, abundant food supply, and a high percent cover of small diameter woody material and soft soil. Mountain beaver have a limited distribution along the west coast of the United States, from Point Reyes, California north and slightly into British Columbia. Of the seven subspecies of mountain beaver, four are effectively endemic to California. The Point Arena mountain beaver is a federally-listed endangered species.