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Castor canadensis Kuhl, 1820
Beaver; Canadian Beaver; North American Beaver
Family: Castoridae
Introduction to the Mammals of BC

Photograph

© Diane Williamson     (Photo ID #10353)

Map

Introduction


The Beaver is an aquatic species of rodent found in BC throughout the province in lakes, along rivers and streams, and in the brackish, tidal waters along the coast. It is easily recognized by its large size, small ears and eyes, brown coloration, and large flat, broad, scaly tail. The tail is slapped on the water to create an alarm sound when threatened. It has strong teeth, including large, orange incisors. The front feet are clawed and the hind feet are webbed (Nagorsen 2005).

The Beaver is the largest species of rodent in North America and is probably the rodent most familiar to Canadians. It is the Canadian national symbol, and its role in the history of Canada through the fur-trade is well documented.

The presence of beaver in a pond or lake is easily spotted by the presence of beaver lodges, or by felled trees in the area that show the characteristic marks of beaver work.

The Beaver requires a stable water source, such as a lake, pond, or stream and, generally, an abundant source of woody plants. According to Nagorsen (2005), preference is for narrow streams that can be dammed to control water levels: "The water level must be of sufficient depth to avoid freezing solid in winter and to accommodate the Beaver's lodges or burrows, den, and food caches." He also notes that while the Beaver is found throughout BC, it is less successful in coastal forests than in interior wetlands.

Nagorsen (2005) indicates that there are twenty-four subspecies of Beaver in North America, with four found in British Columbia. These are:

1) Castor canadensis belugae (coastal mainland and islands to Dean Inlet)

2) Castor canadensis canadensis (northeastern BC)

3) Castor canadensis leucodontus (southern interior and southwestern coastal mainland to Rivers Inlet, Vancouver Island and adjacent islands)

4) Castor canadensis sagittatus (central interior of BC to Kamloops and Glacier)

Species Information

The Beaver is an aquatic species of rodent that is easily recognized by its large size, small ears and eyes, brown coloration, and large flat, broad, scaly tail. The tail is slapped on the water to create an alarm sound when threatened. Adults weigh from 16 to 32 kg and, including the tail, may be up to 1.3 m long (Hinterland Who's Who 2011). It has strong teeth, including large, orange incisors. The front feet are clawed and the hind feet are webbed (Nagorsen 2005).

Biology


"This animal cuts down an average of 216 trees a year. It can fell trees up to about 40 cm in diameter. Usually a single beaver cuts a tree, but sometimes two work on a large one." (Hinterland Who's Who 2011)
Reproduction

Young are born in May or June, with three or four kits in a litter. The kits remain with their parents until they are two or three years old, then they disperse to find their own suitable sites for building lodges and dams.
Diet

The Beaver is herbivorous. In winter, it feeds on woody branches and twigs that are stored in a food cache under water. Adults will bring food from the cache into the lodge for consumption. In summer, food sources are more variable and include many herbaceous plants, their roots and fruits. Favourite plant foods include quaking aspen, cottonwood, willow, alder, birch, maple, cherry, sedges, pondweed, and water lilies.
Behaviour

The Beaver is most active at dawn or dusk, but may also be observed feeding or swimming during the day. It is a monogamous, colonial animal that lives in family groups that consist of "a breeding pair, newborns and yearling animals born the previous year; a few non-breeding animals older than a year may be found in some colonies" (Nagorsen 2005). It is known for its engineering abilities and builds dams, canals and dome-shaped lodges. The presence of beaver in an area is easily observed by the presence of a beaver lodge in a lake or pond, or along a streambank, and by dams along creeks and streams.

Habitat


The Beaver is an aquatic rodent and requires a stable water source, such as a lake, pond, or stream and, generally, an abundant source of woody plants. According to Nagorsen (2005), preference is for narrow streams that can be dammed to control water levels: "The water level must be of sufficient depth to avoid freezing solid in winter and to accommodate the Beaver's lodges or burrows, den, and food caches." He also notes that while the Beaver is found throughout BC, it is less successful in coastal forests than in interior wetlands. In BC, the Beaver may also inhabit tidal brackish water areas in coastal sloughs, where lodges are constructed in the slough bank. An example of this is the presence of beaver in Scotch Pond in Steveston, a primarily treeless habitat located at the edge of Sturgeon Banks marsh. The mild climate in this area allows year round access to non-woody food sources.

Distribution

Global Range

The Beaver is found from northern Canada and Alaska south to northern Mexico.
Distribution in British Columbia

In British Columbia, the beaver is found throughout the province in lakes, along rivers and streams, and even in the brackish, tidal waters along the coast, where it can be observed in sloughs and along the shoreline.

Taxonomy


Nagorsen (2005) indicates that there are twenty-four subspecies of Beaver in North America, with four found in British Columbia. These are:

1) Castor canadensis belugae (coastal mainland and islands to Dean Inlet)
2) Castor canadensis canadensis (northeastern BC)
3) Castor canadensis leucodontus (southern interior and southwestern coastal mainland to Rivers Inlet, Vancouver Island and adjacent islands)
4) Castor canadensis sagittatus (central interior of BC to Kamloops and Glacier)

Status Information

Origin StatusProvincial StatusBC List
(Red Blue List)		COSEWIC
NativeS5YellowNot Listed



BC Ministry of Environment: BC Species and Ecosystems Explorer--the authoritative source for conservation information in British Columbia.

Species References

Nagorsen, David W. 2005. Rodents and Lagomorphs of British Columbia. Royal BC Museum Handbook, Victoria.

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