Get Wild: Beavers are the answer

Bill Betz
Get Wild
This beaver kit was rescued in Aurora and relocated with three siblings and its parents to a private ranch in the mountains.
Photo by Sarah Koenigsberg /

Editor’s note: This story has been updated to correctly identify Sarah Marshall.

In Summit County, beavers are neighbors to ranchers and urban dwellers, and in both cases, their reputation has not fared well. They flood fields and roads with their dams and find ornamental trees in town irresistibly yummy.

They’re called nuisance beavers, but things are changing.

Biologists have long documented how beaver ponds enrich the ecological habitat for innumerable species of plants and animals, and as people realize the toll of global extinctions and the grave loss of biodiversity, a different descriptor for beavers is gaining traction: keystone species.

More recently, large-scale studies using satellite imagery have shown that beavers significantly mitigate the devastation of wildfires. For example, extensive analysis by ecohydrologist Emily Fairfax of wildfires in five western states, including Colorado, showed that beaver presence reduced the fire damage overall by threefold compared with damage near streams lacking beavers.

The reasons are well known: Beaver ponds feed groundwater, which allows plants to withstand drought and wildfire better. And it doesn’t end with plants. Beaver ponds provide refugia — places where organisms can survive unfavorable conditions — for animals imperiled by fire or other existential threats. Given the explosive increase of wildfires in the West, these results are perking up ears at public agencies.

As this data emerges into public consciousness in Summit County — where the combination of serious drought, rising temperatures and a colossal fuel load created by beetle-killed pine trees leaves us all wondering whether we will be the next to suffer the consequences of a devastating fire — one naturally wonders what can be done.

While it’s clear that beavers can help, no comprehensive inventory of Summit County’s beaver population exists. My anecdotal information suggests that the county beaver population is depleted, maybe seriously. If that is correct, we must identify places where beaver reintroduction could help to fill the desiccated sponge that used to hold our groundwater and mitigate any future wildfires.

Moving nuisance beavers from problematic locations in towns to these places in need of their services is another reintroduction benefit — a no-brainer. To identify the best sites, very recent research from the Beaver Restoration Assessment Tool provides an answer.

Map from Dr. Sarah Marshall and Juli Scamardo / Colorado State University’s Colorado Natural Heritage Program for beaver habitat suitability

The tool has been applied to every stream in Colorado by Sarah Marshall and colleagues at Colorado State University, creating a map that shows the beaver carrying capacity of streams in Summit County. It is clear that these streams could support many hundreds of beavers. Moreover, these regions overlap with those of beetle-killed pine trees, where the fire danger is greatest.

And the benefits of beavers aren’t limited to drought areas.

In the upper Midwest, drought is not the problem but rather increased precipitation in the form of more frequent megastorms with consequent flooding of cities like Milwaukee. Data shows that upstream beaver dams could reduce the flooding by about 40% by buffering the water flow and reduce the economic cost of flood damage much, much more (beavers work for free).

Bill Betz

Thus, beavers help us with both drought and deluge! As one observer has said, “Beavers are the answer. The question is irrelevant.”

It seems reasonable to ask our land managers to take a close look at the value and possibility of reintroducing beavers to our streams. In that regard, the upcoming Colorado Beaver Summit from Oct. 20-22 in Avon will provide an excellent platform to explore such possibilities.

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