Mountain? Beaver? Neither!

For the first time in Cascadia Wild history a mountain beaver visited one of our camera survey sites. While it may not seem exciting at first, this is a significant moment for Cascadia Wild as our camera surveys prove time and again the right time, right place matters when it comes to collecting data for conservation. 
​
Our cameras are placed to capture more details of the range and behaviors of our target species. Mountain beavers are not one of these target species, but this sighting was surprising considering their extremely small home range. Catching sight of one from a stationary camera site is quite a feat even for this widespread rodent of the Pacific Northwest. 

​Range: Mountain beavers (Aplodontia rufa) are restricted to the temperate rain forest regions of the North American Pacific coast and few microenvironments inland that have plenty of moisture. They are found in the Cascade Mountains of British Columbia, throughout the Cascade Mountain Range in Washington and Oregon, and in some select sections of western California. Mountain beavers build expansive burrows, with many twists and turns leading to new food sources and places for storage of food to be eaten later. Burrows often have vegetation or sticks ‘tented’ over the multiple entrances as a method of wilting or drying the food before transferring it inside for storage. These beavers generally stay within a few meters of their burrows, relying on stockpiles in the burrow and favored resources nearby to sustain them through the winter.

above: an image of a mountain beaver burrow, notice the vegetation stacked around the entrance

Appearance and lifestyle: Mountain beavers are usually dark gray or brown, with some variation based on the specific subspecies, with a distinct light patch under each ear. While this little rodent is named ‘beaver’ it is more closely related to squirrels than the larger of its namesake. Adults average up to two pounds in weight and anywhere from 12 to 20 inches long with a characteristically short tail. Mountain beavers do not fell trees or build dams like true North American beavers, nor do they go into torpor or hibernate like some other rodents. Mountain beavers prefer to be nocturnal, feeding at night on sword ferns, bracken, grasses, and the bark of coniferous and hardwood trees. In Oregon specifically, they have been noted to preferentially feed on sword ferns, hemlock needles, and salal, a PNW native plant that is largely distasted by other animals.

above: an image of a mountain beaver at night

Lifecycle (behavior and breeding): Breeding season is in late winter with gestation and can last four weeks long. Litters of three to five young are born in early spring. The altricial young start out completely dependent on their mother, but are quickly weaned and then disperse to build their own burrows within the year. Mountain beavers life expectancy is slightly longer than your average rodent - lasting anywhere from 5-10 years with reproductive maturity occurring at age 2.

Conservation status and threats: Common predators in the PNW of mountain beavers include coyotes, bobcats, and golden eagles - though the mountain beaver population is nowhere near being reduced solely from predation. 
​
The IUCN lists the mountain beaver as a species of least concern. The principal threat to this subspecies is habitat loss due to deforestation and climate change and pest control measures to limit burrowing activity and bark stripping.