American Beaver

Castor canadensis

It’s impossible to talk about the important aquatic species of the Pacific Northwest and not include the American Beaver. This species is probably most responsible for human settlement in the area, particularly along the Columbia River. Its resilient, waterproof hide was much sought after by both Native Americans and Europeans as a component in clothing and as a trade item. During the height of the fur trade, as many as three thousand beavers were being killed every year in Oregon. Within twenty-five years, however, their numbers had dropped so dramatically that less than four-hundred could be claimed every year. The decline of the beaver had a resounding effect on other aquatic species, particularly salmon.

Industrious by nature, beavers would build dams and lodges the created isolated pools used by spawning salmon. As trappers removed the beaver from the ecosystem, they unintentionally contributed to the decline in the salmon population, an economic and environmental problem that continues to this day. By the turn of the twentieth century, beavers were virtually extinct. Only protective legislation and beaver fur garments falling out of popularity kept the species from disappearing altogether.

The American Beaver is the largest rodent in North America with adults averaging about 40 pounds (18 kg) and measuring up to 3 feet (.91 meters). They have heavy, squat bodies and a broad flat tale which is used to help them swim, stabilize themselves on land, or warn of approaching danger when they slap it against the water. Their coat is shiny, course and dark brown in color. They have small ears and a wide face. Their front teeth (incisors) are very large and perfectly adapted for chewing through wood. These teeth never stop growing, so the beaver must chew continually in order to keep them ground down.

The American Beaver is the state animal of Oregon. A representation of a beaver dam can be seen on the Aquarium grounds at the base of the stream that runs under our entry walkway.

Range and Habitat

In Oregon, the American Beaver is found along waterways such as rivers, streams, lakes, marshes, and even human-made aqueducts. Their presence is easily ascertained by the destruction of trees and other vegetation in the area; or the building of dams and lodges which may block water flow or form shallow pools. For these reasons, they are sometimes considered a nuisance animal.

Conservation Status

The American Beaver is classified as a protected furbearing animal in Oregon and can only be killed through regulated trapping. Nationally, it has been considered an endangered species since 1976.

Photo credit: USFWS