Mountain beaver burrow systems support a community of vertebrates and other animals. Skunks, salamanders, moles, voles, shrews, chipmunks, ground squirrels, mice, woodrats, gophers, weasels, mink, hares and brush rabbits have all been trapped in mountain beaver burrows. These animals may have been present as commensals, predators, or by accident. There is also a unique invertebrate fauna associated with mountain beaver. The coevolution of the two organisms has never been investigated but, given the ancient lineage of mountain beaver, may provide some interesting insights.
Mountain beaver are strict herbivores.
They are known to eat a wide range of plant species, which often includes just about all species within reach of the burrows. Herbaceous plants are eaten whole while woody plants are discarded after the bark has been peeled off for food. Clipped vegetation can often be observed near burrow systems. Mountain beaver are voracious eaters. Studies have shown that the majority of their active time is spent gathering, handling and eating food.