Beavers head north into Alaska free of predators
Scientists say vast numbers have been enticed by a lack of predators and a thawing permafrost that means more vegetation.
As the warming climate makes Alaska’s far north more hospitable, developers are moving in. But one builder does not have to wait for permits or environmental assessments before transforming the landscape.
Scientists say vast numbers of beavers are moving north, enticed by a lack of predators and a thawing permafrost that means more vegetation.
They are building dams that alter the flow of streams and create ponds, which contain warmer water that further melts the permafrost.
The newly thawed ground then releases greenhouse gases, fuelling the warming climate.
Ken Tape, an ecologist at Alaska Fairbanks University, studied satellite images of streams, rivers and lakes in the tundra and found more than 11,000 beaver ponds.
Aerial photographs from the 1950s show no beaver ponds in Arctic Alaska.
“The lightbulb moment was recognising that the beavers leave a footprint on the landscape that you can see from space,” Dr Tape said.
“It’s obvious in the satellite imagery when a beaver has moved in because suddenly that little stream is gone and there’s a pond or a series of giant ponds. You can’t miss it.”
Dr Tape said that whether the beavers’ seemingly unstoppable proliferation was a bad thing depended on your perspective.
On one hand they represent an increase in local biodiversity; they also, however, exacerbate the effects of climate change.
Dr Tape said only one other species could cause the same disturbance in so little time: humans. But even humans would be stopped by their government, he added.
“If a developer wanted to do what beavers are doing in the Arctic right now, they could not get a permit,” he said.
“They (the government) would just laugh you out of the building.”
Dr Tape said the closest likeness for the changes inflicted by beavers was not another animal but a far more destructive force.
“You shouldn’t think of beavers as a new species moving into the Arctic,” he said.
“That really doesn’t begin to grasp the scope of it. It’s a new disturbance regime. So wildfires moving into the Arctic is the best analogy to beavers.”
How to tackle the problem of the beavers’ incursion is an open question among scientists. The animals’ advance into Alaska has been documented but their presence in northern Canada is still being studied.
In terms of their management, “that conversation has just begun”, Dr Tape said.
“If I had to guess, I’d say there’s very little we can do.”
The Times
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