Beavers are no longer cold in their eyes. Rodents are increasingly colonizing the arctic tundra of Alaska, according to a study published in early December by the US National Oceanic and Atmospheric Administration (NOAA). Under the effect of climate change, living conditions in the north are more and more adapted to beavers, while the environment in the south is less and less. This could explain their presence in regions which were, until a few years ago, uninhabitable. The decrease in poaching is also a factor put forward.
In this region where global warming is three times faster than in the rest of the world, the presence of beavers is not only a symptom, it is also a potential factor of acceleration of the upheaval underway. Once in the Arctic, the beavers are reshaping the landscape. While rivers are diverted, others are created by its dam activity. “They change the hydrology of the area”, said Ken Tape, a researcher at the University of Alaska and co-author of the study, in an interview with Guardian. An upheaval and an accumulation of water in the swamps which causes the permafrost to melt, these layers of soil permanently frozen. Locked initially in the frozen ground, powerful greenhouse gases, carbon dioxide and methane, are then released into the atmosphere.
Beaver migration also affects human populations living north of the Arctic Circle. By redrawing the landscape in this way, rodents are forcing them to readjust their way of life. Whether it is for their journeys, affected by the mutation of rivers and the floods it causes, but also for their access to water, especially with regard to fishing.
Twenty times more swamps
To carry out this study, the international team of researchers relied on thousands of satellite images, preciously collected since 1949. A long-term study therefore, which made it possible to quantify the appearance of swamps created by beavers in the region. In particular, the researchers mapped the dams and calculated the increase in the surface area of water. According to their findings, the number of ponds created by beavers that dyke rivers and streams in western Alaska has increased 20-fold.
However, the number of these rodents, estimated to be between 50,000 and 100,000, is not known. “There are regions in Alaska where there was no trace of beavers fifty years ago and which are now saturated with them”, details Ken Tape. In order to continue tracking this disturbing migration, study scientists created an observing network, the Arctic Beaver Observation Network (A-BON). It will continue the data collection work. A first meeting is scheduled for March 2022.
But even before his first conclusions, Ken Tape worries: “It’s just a matter of time before the beavers move further north. When you realize that this is probably happening across the rest of the Arctic to Canada and Russia, it gives you an idea of the magnitude of this change. ”