Mountain beavers (Aplodontia rufa) are believed to be the genetically oldest living “rodent” species in the world and are also considered to be “prehistoric”. Interestingly, they are not actually directly related to true aquatic Beavers (Castor canadensis) at all though. The two species only share the name due to their ability to chomp on bark, limbs, twigs, and other foliage/parts of trees. Some people like to refer to mountain beavers as “Boomers”, however it really has no significant meaning and is just a common nickname for them.
Their bodies are usually somewhere between the size of a hamster and a guinea pig (around 11-13 inches long) and their fur can range from brown, light grey, or even dark greyish and almost black in color. Mountain beavers possess a pretty impressive set of claws, especially for an animal their size. For being such a small critter they can cause immense damage to landscaping! Whether it is causing erosion issues from their burrows, demolishing professional rhododendron gardens, or tunneling underneath sheds and other structures, they’re pesky little animals. Two simple ways to identify if they have been around are tunnels/burrows in the ground that are approximately 8” in diameter and shrubs being chewed on at a 45 degree angle. Not very many other critters in the Pacific Northwest region cause these same kinds of damage.
Mountain beavers primarily live in damp areas, usually where ferns, salal, and/or ivy is abundant. It is very common to find high populations of them in low lying vegetation where they have good cover away from predators (coyotes, cats, birds of prey, etc). They are only found in parts of British Columbia, Washington, Oregon, and a little bit into Northern California. No where else in the world can these unique critters be found!
