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Beaver Needs  

The Beaver Beavers are Canadian symbols, but they are also good symbols of the environmental needs of wildlife.  An average sized adult beaver weighs about 20 kilograms or 45 pounds: not the largest animal in the boreal forest, but far from the smallest as well.  Typically beavers live in family units of two adult beavers and 3-4 kits.  Year old beavers also usually remain with their families so the average will house about 6 animals.

What makes beavers remarkable is the way they adapt their habitat to suit their needs.  The dam is perhaps the most obvious example of this.  Typically built across a slowly flowing river or stream, beaver dams are often 45 metres long (150 feet) and two metres (6 feet) high.  They can be up to 3 metres or about 10 feet wide at their base.  This dam needs to be large enough to create a pond 2 to 3 metres deep; deep enough that it will not completely freeze to the bottom even in the coldest winters.  Built of branches, stones, roots and mud a typical dam will consist of about 250-280 cubic metres of material.  But that is not all a beaver needs.  A beaver lodge that is 2 metres high and 6 metres (or 20 feet) in diameter will need another 20 or more cubic metres of material.  In total then, every beaver family needs enough lodge and dam material to fill a small two bedroom bungalow.

In addition, beavers need food:  approximately 660 grams or aboutThe Work of a Beaver 1.5 pounds of pond vegetation, leaves, buds and bark from trees every day.  The favorite food of beavers is the inner bark, or cambium, of the aspen or poplar.  Naturalists estimate that each beaver colony will need over 200 trees a year for food and building material.  This is about the number of aspen of suitable size found on about .4 hectares or one acre of land.  These trees also need to be located close to the pond because of predators.

So beavers need a lot of boreal forest: flowing water to dam into a pond, lots of building material, and plenty of food located close to the pond.  It is not easy to find the right conditions, so only a small part of the boreal forest is really suitable as beaver habitat.

 
Reprinted with permission of Alberta Community Development, Cultural Facilities and Historical Resources Division.

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