Beavers are superhero rodents in California’s fight against climate change

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To anyone else, the forest along McGarvey Creek has the look of a verdant wonderland. Leaves pinwheel down past moss-covered trunks. A foothill yellow-legged frog keeps watch as clear water trickles by.

To Sarah Beesley, though, “this looks like absolute crap.”

The landscape is missing the redwoods that towered into the sky before loggers arrived. And it’s missing the beavers that flourished before trappers nearly extinguished them from what is now California.

The lack of beavers is not for lack of trying. Ms. Beesley is a fisheries biologist for the Yurok Tribe, whose ancestral territory lies in the coastal waters and redwood forests of northwestern California. Pioneers in environmental restoration in the state, the Yurok have built artificial beaver dams and installed logjams to slow the destructive energy of waterways like McGarvey Creek, all in hopes of restoring past flows, bringing back beavers and, with their help, improving habitat for salmon.

Now, the rest of California is trying to do the same, elevating the lowly beaver into a much-wanted global warming warrior.

Research has shown that watersheds inhabited by beavers are wetter and greener, more resistant to wildfires and more productive for agriculture. That has made them newly coveted agents of environmental healing as tinder-dry forests burn in great masses and vast parts of the continent go parched from a worsening drought.

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“Beavers are an untapped, creative climate-solving hero that helps prevent the loss of biodiversity facing California,” in the language of a state budget request document filed earlier this year. California has since promised US$3-million to hire five scientists for a beaver restoration program over the next two years, stoking visions of freshly recruited corps of critter labourers fanning out across the state.

California is a late addition to the ranks of “beaver believer” states in the U.S., where widespread struggles with drought and poor salmon stocks are driving new approaches to harness the energies of a rodent that reproduces quickly and stores water, as a biological imperative. In California, the shift follows decades of effort that included advocacy groups hiring a Sacramento lobbyist as a beaver booster.

But the Yurok and others have found that bringing back a species that once numbered in the hundreds of millions across North America – and one still regularly exterminated as a pest – can be complex and costly.

Place a beaver in an area that has been managed for logging, “and it’s going to struggle,” said Yurok vice-chairman Frankie Myers. “Because it’s meant to survive in an ecosystem, and most of our watersheds now aren’t ecosystems. They’re plantations.”

To entice a beaver to stay around McGarvey Creek, the Yurok have even trucked in willow cuttings for them to eat. That worked, for a while. But lately, the beavers have been scarce. It may be that “there’s just not enough food to keep them here,” Ms. Beesley said.

The problems encountered by the Yurok reflect a difficult reality for attempts to reverse the toll of industrialization – and, before that, colonization – on landscapes where humans are now struggling to maintain the necessities of life.

Beavers are remarkable rodents, capable of surviving in environments far from the boreal rivers and lakes where they are familiar to Canadians. “They thrive in desert,” said Emily Fairfax, a scholar at California State University Channel Islands. Her research has shown beavers’ value as firefighters, their dams sustaining greening oases less likely to burn in forest blazes.

As California looks for new ways to confront worsening drought, Prof. Fairfax thinks beavers “have an absolutely enormous potential” to help. The current North American beaver population is likely a tenth of what it was before the arrival of the European fur trade. Restoring even part of that could result in “a lot of water” stored on the landscape, she said.

The effort to bring back the beaver in California began with rewriting history. For decades, the state relied on habitat maps informed by research completed after trappers had largely exterminated beavers. It took years of studying ancient dam remains, scouring old newspaper accounts and documenting terms for beaver in Indigenous languages to prove that beavers actually once lived across most of the state.

That was “what we needed to get the California Department of Fish and Wildlife to stop treating them as a pest, but as a potential ecosystem engineer,” said Rick Lanman, an oncologist who led the effort.

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Nonetheless, California authorities issued permits to get rid of 3,000 beavers last year, often by killing them – although there are no statistics on successful exterminations.

Beaver advocates are pushing for a three-strikes rule, where beavers are only killed after attempts first to live with them – by protecting valuable trees and installing devices to prevent flooding from dams – and, if that fails, to relocate them.

“The beaver is basically a stormtrooper to come in and support our living lifeboats, the watersheds,” said Brock Dolman, a researcher who has helped co-ordinate a Bring Back the Beaver campaign. (He gives Canadian nickels as gifts.).

“We think our watersheds need thousands and thousands of new dams. We want them to be maybe three to four feet tall, made of sticks and wood,” he said. “And we want a whole crew of mammals with sharp teeth who are managing them for free.”

Beavers can, however, provide at best a partial solution to the enormous task of securing sufficient water to sate the thirst of the state’s industry, agriculture and human residents. “Is L.A. going to swap over to beaver water for their supply any time soon?” Mr. Dolman said.

“Don’t think so.”

The last time California sought to bring back beavers, nearly a century ago, it parachuted them in to remote mountain regions. Some of the beavers in the state today are believed to be descended from those high-fliers.

While no one is advocating a reprise of such measures today, more recent experience has shown that beavers can be surprisingly difficult to keep in the places they are desired, even when delivered by gentler means.

Drought has left some streambeds dry; others run so fast that beavers can’t effectively build dams. Changing environmental conditions have also stripped away cottonwood and aspen trees, favoured by beaver as food.

It would take “a thousand years” for beavers to undo that by themselves, said Scott Campbell, a veterinarian who has fought to change laws in Oregon, where he has sought to use beavers to rehabilitate waterways on a large ranch.

Recreating homes for them is not always simple. Artificial beaver dams can help, but even in Oregon, the Beaver State, the work to secure a permit for such a structure can cost hundreds of thousands of dollars, Mr. Campbell said.

Then there is food. Returning enough cottonwood and aspen to the landscape is especially difficult. Mr. Campbell nurtured one small stand of aspen behind tall fences, at a cost of US$25,000 – only for snowdrifts to let beavers cross inside. They cut them all down.

“They’d been lusting for the aspen for years,” Mr. Campbell said.

The Yurok, too, have found that for beavers to transform a landscape, the landscape itself needs to be transformed first.

“We need to get in there to repair the damage and destruction from the last 100 years,” said Mr. Myers, the Yurok vice chairman. Only then “can we get to a place for beavers to move in – so they’ll actually have a place to thrive.”