BEFORE AND AFTER — Satellite images of a stream near Nome show just how quickly beavers can change tundra landscapes.

Beaver colonization around Nome is a ‘harbinger’ of Arctic changes

By Megan Gannon
Though much of the Seward Peninsula remains untouched by development, one group of architects has been engineering steady changes: Beavers. They are expanding further into the Arctic as climate change creates warmer, more favorable conditions for these critters. They build impressive lodges out of logs and mud. They dam rivers. They flood roads. They turn winding streams into systems of ponds that thaw permafrost. As residents of the Bering Strait region learn to live with these relatively new neighbors, scientists seek to understand the impact of beaver colonization.
Ken Tape, an ecologist at the University of Alaska Fairbanks, was in Nome last month with a team of field researchers examining beaver ponds, but he never set out to become a beaver specialist. In his earlier work, he tracked the expansion of shrubby vegetation in the Arctic—and the boreal species that followed. Moose populations are shifting into new tundra territory as more shrubs are available for foraging in the winter. Migratory birds arrive earlier, too, in response to earlier spring conditions. Such wildlife changes are notoriously hard to measure, Tape said. But beavers leave an obvious footprint on the landscape.
“What really was exciting about them is being able to detect the formation of ponds from space,” Tape said.
People in western Alaska had been aware of the presence of beavers for decades. “I’m 47, I spent most of my life here in Nome, and as far as I can remember, there’s always been beavers,” said Brandon Ahmasuk, Kawerak’s Vice President of Natural Resources. “Now somebody who’s older, like say my father, he just turned 90 this last April, he may have a very different take on it.”
As far as the science community was concerned, beavers were not considered an Arctic species. Their colonization had not yet been documented. Tape’s expertise in remote sensing helped capture the scale and speed of the phenomenon. He and a group of colleagues started looking at Landsat satellite images of the region. They announced their first results in 2017, showing that beavers had dammed more than 50 Arctic streams between 1999 and 2014.
The researchers published their latest study in the journal Scientific Reports in May of this year, with even more dramatic findings. By looking at 70 years of satellite images and aerial photography, they mapped more than 11,000 beaver ponds in the Alaska Arctic (beyond the treeline), largely in the Seward Peninsula and the Northwest Arctic Borough. Between 2003 and 2017, the number of beaver ponds in the region had doubled. Tape and his colleagues found no evidence of beavers in their earliest aerial images from 1952, but signs of beaver engineering started showing up in the 1970s, which tracks with the observations of residents.
That it took so long for scientists to pay more attention beaver colonization here perhaps speaks to Nome’s not-always prominent place in Arctic research. Scientists are more likely to use a base like Toolik Field Station, operated UAF’s Institute of Arctic Biology in the northern foothills of the Brooks Range, Tape said. Toolik’s infrastructure and funding—the station, which is accessible by road from Fairbanks, just received almost $20 million for its next five years of operations—make it an obvious choice for researchers to execute their fieldwork. But the Arctic is not changing uniformly. There are no beavers yet in the North Slope.
“So much research is focused there, we miss important questions that are emerging or are relevant in western Alaska,” Tape said. “The Seward Peninsula is really a harbinger of what is in store for the rest of the Arctic.”
Now that Tape has documented beaver colonization from above, he is getting closer to the ground to grasp the ecological changes these mammals bring. Beavers are not just responding to a changing climate; their engineering projects could be making warming worse by thawing carbon-storing Arctic permafrost.
“Our hypothesis is that because these beaver ponds absorb more heat than the pre-existing kind of vegetation—and they thaw permafrost—they’re creating oases,” Tape said. “When you make deeper water, you make more unfrozen water in winter. We think these are places of greater biodiversity, and they’re essentially accelerating, or exacerbating, the effects of climate change in these locations.”
Tape and his colleagues launched a five-year fieldwork program in 2021. When they returned to Nome last month, they visited several ponds—some close to the roads, others only accessible by helicopter—and took measurements of basic physical features like the water’s depth, temperature and quality. They’ll be back in March to study the conditions during winter, with added investigations of factors like snow depth and the amount of unfrozen water. “In the winter, it’s mostly a quest to see how much of the landscape is unfrozen in these beaver-affected areas versus the unaffected areas,” Tape said.
Tape said he hopes his research could influence challenging decisions around beaver management. Expensive but effective devices like the “beaver deceiver” installed at Pilgrim Hot Springs last year can prevent serious flooding. Hunters can harvest beavers to reduce their numbers, too. But these established mitigation techniques are largely restricted to targeted areas near roads. The vast, inaccessible stretches of permafrost are changing just as rapidly.
“Fly around in a helicopter, or fly around in Google Earth, and you will see that these guys are taking over lowland ecosystems in the Arctic,” Tape said. “I just cannot imagine how we’re going to prevent that.”
Beaver management not only presents daunting logistical questions, but more philosophical ones, too. Should humans intervene at all? That depends on who you talk to. Tape said he’s often asked whether the beaver takeover is a good or bad thing.
“If you like the Arctic the way it was, then it’s a bad thing,” he said. “If you like carbon stored in permafrost, it’s probably a bad thing.” On the upside, the new ecosystem engineered by beavers will likely increase fish biodiversity where fish thrive. “Although, I don’t think it’s a foregone conclusion that beavers have a positive or a negative effect on fish,” Tape said. “I think it’s complicated.”

Caroline Brown, the statewide research director for the Division of Subsistence at the Alaska Department of Fish & Game, said she’s heard residents express worry about beavers’ effect on water quality and how their engineered changes could prevent subsistence users from navigating waterways or fish from getting to their habitats.
“People have a lot of concerns about beaver disturbances doing things like blocking fish movement,” Brown said.
Ahmasuk has also been fielding concerns about beavers and the mixed bag of their effects on the landscape. He gets another type of question from subsistence users: “Can we eat beavers?”
“Because they’re newer to the Seward Peninsula, it’s not something that people traditionally harvested,” Ahmasuk said. He’s harvested beavers before, and described the meat as fatty and tender, tasting faintly of willows. His message to prospective hunters and trappers: “Don’t be afraid to try them.”
Subsistence users have a wealth of knowledge about changes on the tundra that Tape and his colleagues hope to incorporate in their work. The researchers plan to interview residents in Kotzebue, Noatak and Shungnak about their experiences and observations. Beavers have been established in large numbers in Shungnak for at least 20 years, Brown said. Kotzebue, however, only witnessed a huge increase in beaver engineering in the last 20 years, while Noatak is right on the expanding edge of animals’ range.
“We chose those three communities specifically because they are in three different stages of beaver impact,” said Brown, who is one of Tape’s collaborators in the fieldwork program.
Though the project’s ethnographic component will be centered in Northwest Arctic Borough, the researchers want to hear about beaver experiences and observations from people Nome, too. Tape will be giving a Strait Science presentation about his research on Oct. 6.

This story was first published on Sept. 08, 2022


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