Mountain Beaver: Aplodontidae

This animal is also commonly called sewellel, named after the Chinook (American Indian tribe) word for a robe made from its pelts. There is only one species of mountain beaver and they are not closely related to the true beaver. These animals are about the same size as a squirrel, with a head and body length of 14.3 inches (36 centimeters), and a tall length of approximately 1.2 inches (3 centimeters).

They have a thickset, heavy body and short limbs. Eyes and ears are small. The head is broad and relatively flat. The neck is short and thick. All the limbs have five well-developed claws. These animals appear nearly tail-less because the tail is so short. They have strong incisors (chisel-shaped teeth at the front of the mouth).

The fur on these animals is thick, short, and typically a grayish, dark brown or reddish brown color, with sparse guard hair, which are coarse hairs that form the outer fur. Lighter, thick fur lies underneath, which is called the underfur. Guard hairs protect the underfur. Its belly is a slightly paler color, a white or chestnut brown. There is a small white patch of short fur at the bottom of its ears.