Beaver

In Canada the beaver is a national symbol and an important of history. It is a source of food and clothing for aboriginal people. Beavers are also important animals because their dams provide habitats for other mammals such as mink, muskrats, and otters. Different observers have cited that beaver benefit other wildlife including fish, moose, waterfowl and variety of other birds.

The negative side is that beavers cost North America millions of dollars every year by causing flooding and damage to private and public property. This summery is about how to handle this valuable resource.

Biology

Habitat

Beaver live along the slower-moving sections of rivers and streams as well as on pond shores of small lakes not exposed to heavy wave action. They prefer muddy shores and bottom areas because rock and gravel make channelling, burrowing and damming difficult. For the winter, there must be water near the lodge deep enough so that it blocks access to the flood cache and to allowing beavers toescape from predators.

Food

Beavers are vegetarians that eat a variety of plants in the summer, including grasses, forbs, the leaves of shrubs, and pond lilies. During the long winter season they eat the bark and twigs of certain deciduous trees and shrubs, particularly aspen, cottonwood, and willow.

A colony of beavers overuse their food supply, specifically aspen. They will usually cut more than they need and drown food supplies in the rising waters behind their dams. It takes only two or three years for a beaver colony to use up the aspen. Fortunately, willow often lasts longer because it grows fast enough, tallowing the beavers to live a few years more at the same place.

Reproduction

A dominant pair in active colonies usually produce only one litter per year. One litter consist mostly of three or four pups. But the litter size increases with the age and size of the female beaver. The best age for reproductive capacity is between five and nine years.

Mortality

In northern areas, climatic factors are particularly important to beavers, affecting entire colonies. Low temperatures with light snowfall can increase the beavers’ food-energy.

Colonies need an insulating layer of snow and deep ice in the beaver pond to entrap the food cache. Under these harsh conditions, beavers will either starve or dig out. Survival rates are poor for beavers that attempt to forage above the ice.

Winter and spring thaws that raise water levels may flood out colonies at a time when there is nowhere else for them to go, resulting in mass drownings. Rapid spring break-ups can be accompanied by a violent grinding action of ice, destroying lodges and their inhabitants.

Beavers die because of a variety of other reasons. They are sometimes killed by the trees they are felling, and from wounds inflicted by other beavers and by wolves.

Habitat consideration

Forestry in British Columbia impact greatly on beaver habitat. A once stable stream system can reduce the carrying capacity with extensive logging changing drainage patterns. Afforestation practices that eliminate or shorten the deciduous shrub and tree stage of the forest regeneration cycle also have negative impacts on beaver populations.

There are ways to improve beaver habitat colony sites. During the summer trappers can clean up around aspen felling sites and move larger chunks of trees to the water so beavers can use them to build new dam.

They can also help minimize tree waste by knocking down snags and clean areas to make felling easier for the beavers. To reduce the numbers of the hiding spots for predators a solution would be to clean up an aspen stand. It is also helpful for beavers when trappers break up old dams to reduce the water levels around areas where trees can take root.

Conclusion

In conclusion, it is very important to know when to yield on a trap and know the numbers of beaver colonies and the number of beavers per colony, because the average size of beavers depends both on habitat quality and on trapping rotation schedule. Trappers should take care of a healthy balance between the nature and their interest on the fur of the beavers. It’s in interest of all, the humans, the animals and our common habitat.

Beavers in:

  • Source Ministry of Environment. July 1988. Management Guidelines in British Columbia : Beaver. Available at : http://www.env.gov.bc.ca/van-island/pa/pdf/beaver_mgt.pdf [Accessed 03/2021].