Published on January 28, 2020

The Results of a Busy Season for Beavers

Beaver gnawing stick in a pond © Amy Vaughn

Beaver activity seems to reach its peak in fall, when these industrious creatures begin making preparations for winter. And the best way to gauge beaver activity levels is to take a look at the surrounding vegetation.

Recently, a group of volunteers and sanctuary staff did just that. Taking a casual tally along the shore of Stony Brook Pond, they found more than 90 trees and shrubs impacted by beavers within the last several months. 

Of course, understanding the impact of these activities is easier if you know why the beavers are doing it in the first place.

Survival Skills

Beavers remain active throughout winter, which means they have to be prepared. They must make repairs to their dams and lodges to secure them against the cold. And their "larder" must be fully-stocked before easy access to the shoreline and sources of growing vegetation become limited.

Perhaps predictably, beavers have a very clever way of ensuring they'll have enough food to sustain them over the long winter months. After cutting and collecting branches from trees and bushes, they swim down under the water to carefully stick each branch into the mud at the bottom. Then it's back to the surface to repeat the process.

Think of it like the beaver equivalent of a root cellar.

A tree that's been "girdled" by a beaver

Cataloging the Evidence

During that walk around Stony Brook Pond, the group recorded their observations of trees and shrubs impacted by autumn's beaver activity.

Some 9 trees had been girdled, which means the bark surrounding the bottom portion of the trunk was completely removed. The girdled trees included 5 white oaks, a red oak, two grey birches, and a highbush blueberry shrub. Of these, the largest was a white oak that was 19 inches in diameter! 

Another 85 trees and shrubs had been cut down in their entirety and hauled away. That total included 57 blueberries, 15 smilax vines, 5 beech saplings, 4 grey birches, 2 witch hazels, a red oak, and a sweet pepperbush.

Cataloging the damage led to a question that's always asked whenever a landscape undergoes a sudden and dramatic transformation—what would be the impact on the surrounding habitat?

Cause & Effect

The immediate impacts were clearly visible. The cut vegetation had likely already been eaten or was being stored as food for the winter. The girdled trees were either dead or dying due to the damage inflicted on their trunks. But determining the long-term impacts, both positive and negative, isn't easily apparent.

For instance, the types of vegetation growing around the pond could noticeably change. Since the beavers removed quite a number of trees along the pond's edge, large portions of the ground once shaded by a canopy of leaves will receive much more sunlight.

The Takeaway

Yes, living with beavers can be a challenge. But the benefits far outweigh the difficulties.

Ecologically speaking, beavers are what's known as a keystone species. Their natural behaviors, which humans often deem problematic, are actually critical to the creation, health, and survival of freshwater wetlands. There's also the intangible pleasure and joy that observing the beavers and their antics brings to sanctuary visitors. 

And that's well worth the effort we put into living together in the same environment.

Look for signs of these busy creatures on your next visit, and let us know what you think the beavers are up to!