Beavers Are on the Move and It's Changing the Landscape

Beavers are what scientists call “ecosystem engineers.” When they build dams, they create brand new ponds and divert the way rivers flow. This can have a domino effect on the surrounding environment.

A new study finds that North American beavers (Castor canadensis) beavers are moving farther north and expanding their range. As they travel into the Arctic, they’re having a notable impact on the landscape in northern Canada and Alaska.

“When beavers create dams they fundamentally transform environments; we see a transition from a terrestrial to aquatic environment where dams create flooding, river flow and sedimentation also changes. Essentially we see many changes at the same time,” study author Helen Wheeler, senior lecturer in zoology at Anglia Ruskin University in the U.K., tells Treehugger.

“These then cause further changes, for example beaver ponds may be less reflective than what was there before, this means that more radiation from the sun is absorbed rather than reflected and things heat up. This can exacerbate the thawing of permanent frozen land (known as permafrost) and the thawing of permafrost causes the release of carbon dioxide and methane, which are greenhouses gases, which is a concern.”

The impacts are even more widespread as researchers are hearing stories of how local people and their livelihoods are affected by increased beaver activity.

Scientists used satellite imagery to track the beavers as they moved into the new Arctic habitat. They have plotted more than 12,000 beaver ponds so far in western Alaska, with most areas experiencing a doubling of ponds in the past two decades. In contrast, researchers found no beaver ponds when analyzing aerial photographs of the area between 1949 and 1955.

Researchers aren’t exactly sure what is causing the beavers to expand their range and head further north into new habitat.

“This is still actually an open question but there are a number of likely candidates; climate change is one, the arctic is warming particularly rapidly compared to other regions of the earth, 2-3 times more rapidly than the global average and this has now been the case for some time,” Wheeler says.

As a result of warming, there are habitat changes that might create more favorable conditions for beavers.

“In particular, one process occurring in the arctic is that shrubs are moving further north, as beavers often use woody vegetation to build dams and lodges and also feed on this vegetation, this might allow beaver population to expand further north.”

Also, due to a decline in the fur trade, there’s less trapping and hunting in the area.

The results were published in the Arctic Report Card 2021 report, published by the U.S. National Oceanic and Atmospheric Administration (NOAA).

Why Movement Matters

When beavers move into a new area, they have impacts on the landscape and the people in the new place. That’s why it’s been important for scientists to work with Indigenous organizations in the area to help identify research priorities.

“Concerns include the impact of beavers on fish populations and also the ability to access harvesting, hunting and trapping grounds for subsistence activities, there are also concerns about impacts on other species,” Wheeler says. 

When rivers run dry after being dammed by beavers, that can affect local fishing. And when the dams block rivers, that can change accessibility for people in the Arctic.

“As ecosystem engineers, beavers really transform landscapes, and particularly where people’s livelihoods are closely tied to nature, it is understandable that there are concerns,” Wheeler says. “We hope the next stage in our research will be to work closely with community members to better understand the impacts they are observing and how this impacts livelihoods.”

Scientists work with members of local communities to answer their questions and work in partnership with many organizations.

They have a monitoring camp in the Gwich’in Settlement Area in the Canadian Arctic, where community members go out in the field and do research with them. They learn about the changes they have observed, which helps researchers develop hypotheses about how and why beaver populations are changing. And during the pandemic, when other researchers couldn’t travel, community research continued.

The findings and continued study are important for several reasons, researchers say.

“Our increasing understanding of the extent and magnitude of change we are seeing in beaver populations and their distribution highlights that we are really seeing some substantive environmental changes, and climate change is a potential culprit,” Wheeler says. “It also highlights the wide scale ecological and social impacts that these changes can create.”