Mountain Beaver – A volcano eater!

Mountain Beaver

The mountain beaver (Aplodontia rufa) is a North American rodent. It is not related to beavers but is so named because it does chew bark and leaves from trees and ferns like beavers do. I suspect it also has to do with the pelt. When furs were “the thing”, there would have been little care about the difference between this creature and a slightly larger rodent.

It’s scientific name means “red simple tooth” because it is quite a primitive rodent and does not have the complexity of later rodent’s jaws and muscles related to chewing. It has several common names, including: mountain boomer, ground bear, giant mole and sewellel ( this comes from the Chinook term for a cloak made out of pelts).  This animal is the only extant member of it’s family and is more closely related to squirrels than true beavers.

A mountain beaver usually weighs in at 500 gms with a length of about 20 cms. It is reddish or brown in color. They have an interesting burrow structure as shown below.

Mountain Beaver Nest

Why would one keep one’s shit hoarded up in the back like a larder? Well, if you eat it to get maximum nutrition then it makes perfect sense. Yes, like many other animals this cutie does indulge in a bit of coprophagy.

This remarkable animal has a unique teeth structure called hypsodonty. This means that the teeth have high crowns and extend way past the gum line. This condition is seen in a lot of herbivores that eat grass. It helps deal with the grit and dirt that comes with such low nutrition diets. However, mountain beavers of today do not have such a diet. They eat a lot of soft bark and ferns it was considered a bit of a mystery.

Now, the mystery has been resolved with Samantha Hopkins of the University of Oregon figuring out that in the family’s heyday, there were lots volcanoes active in the Yellowstone hotspot and Columbia River Basalts had frequent minor eruptions, spewing out huge swathes of volcanic dust that blanketed the mountain beavers’ habitat. This unexpected volcanic seasoning turned a bunch of soft plants into gritty chunks of silicon. The mountain beavers had to basically eat their way out of this volcanic age, and they developed suitably thick teeth to survive.


The mountain beaver has a range all over the North Pacific region on the United States and Canada. They mate in Spring and a couple of babies are born in a couple of months. They have a fairly long lifespans for rodents of between 5 – 10 years. They have a lot of predators including eagles, bobcats, coyotes and cougars. They are fairly abundant in their range and are marked as “Least Concern” by the Redlist.



About mammal 73 Articles
I blog about mammals and all the interesting and fun-filled facts about them will be welcome additions to this blog.

Be the first to comment

Leave a Reply

Your email address will not be published.