Species Information

About Beavers

The beaver (castor canadensis), a keystone species in our environment, is the largest rodent found in North America. An individual can weigh up to 60 pounds, although the average adult generally weighs between 35 and 40 pounds. 

Trapped to near extinction for their dense waterproof fur soon after European settlement in the United States, the beaver is making a comeback. Their slow, steady recovery has been a godsend for the environment.

Beavers are the world’s greatest builders of small, rich wetlands. The habitats they fashion support a myriad of species including other mammals, wading birds, waterfowl, fish, turtles, mussels, deer, bear, and moose. Beaver habitat also houses sensitive plant species, improves water quality by acting as a settling basin, and controls flooding by slowing water movement.

Beavers live in and around water and constantly modify streams by building dams and impounding flows to create ponds. They are herbivores, feeding on the inner bark layer of woody plants, leaves, shoots and aquatic herbs such as duckweed, water lilies and pond weed. A beaver’s preferred food trees include aspen, birch, willow, cottonwood, poplar, maple, apple, and even oak.

Beavers are monogamous and produce one litter a year, usually between March and June. Because they are territorial and only tolerate the presence of family members under the age of two, families typically disperse, usually traveling less than six miles in search of new homes.

The key to living with beavers is tolerating them, and realizing that they play an important role in establishing and maintaining the wetlands that provide critical environmental functions. 

POSSIBLE CONFLICTS & SOLUTIONS

While problems sometimes arise when beavers come into contact with humans or human property, it’s important to remember that beavers do not create problems in natural or wilderness areas. The two most common human-beaver conflicts are the flooding that results from dam-building and the damage to trees that are used for food or building materials.

Contrary to popular belief, trapping is not an effective means of controlling beaver populations or of solving human-beaver conflicts. In fact, unless it’s extensive and heavy, trapping has been shown to stimulate the production of more young than if the animals are not trapped.

Fortunately, there are some effective solutions to dealing with human-beaver conflicts. Where potential flooding is a problem there are a number of devices —called bafflers, deceivers, levelers, or other similar terms—designed to control water levels without removing or destroying the beavers. Tree protection, fencing, and repellents are also potential solutions. Click here to find companies that create and install these devices.

PUBLIC HEALTH CONCERNS

While beaver have been implicated in the spread of Giardia, it is important to note that to date there is no documentation of a human contracting Giardia from a beaver. It is also important to note that a variety of other animals including humans shed Giardia in their feces and the presence of Giardia in a wetland or watershed may be due to the presence of many different environmental factors. 

RESOURCES ON BEAVERS AND TRAPPING - THE LAW AND IMPLEMENTATION 

WATCH OUR BEAVER VIDEOS ON YOUTUBE

MSPCA BEAVER FACT SHEET pdf

Berkshire residents: thanks to the Thieriot Foundation, MSPCA has grant money to help solve beaver related flooding in the Berkshires. Learn more.