Let’s hear it for nature’s engineers!
Seven years ago, ecologists looking to restore a dried-out Placer County floodplain faced a choice: Spend at least $1 million bringing in heavy machines to revive habitat or try a new approach.
They went for the second option, and turned to nature’s original flood manager to do the work — the beaver.
The creek bed, altered by decades of agricultural use, had looked like a wildfire risk. It came back to life far faster than anticipated after the beavers began building dams that retained water longer.
“It was insane, it was awesome,” said Lynnette Batt, the conservation director of the Placer Land Trust, which owns and maintains the Doty Ravine Preserve.
“It went from dry grassland. .. to totally revegetated, trees popping up, willows, wetland plants of all types, different meandering stream channels across about 60 acres of floodplain,” she said.
The Doty Ravine project cost about $58,000, money that went toward preparing the site for beavers to do their work.
In comparison, a traditional constructed restoration project using heavy equipment across that much land could cost $1 to $2 million, according to Batt.
The project is supported by the U.S. Fish and Wildlife Service, through its Partners for Fish and Wildlife program. Since 2014, it has worked with the Placer Land Trust to restore and enhance habitat for migratory birds, waterfowl, salmon and steelhead by unleashing the beavers, a keystone species.
Damion Ciotti, a restoration biologist for the U.S. Fish and Wildlife Service who led the project, said he predicted the Doty Ravine project would take a decade to reconnect the stream to the floodplain, but to his surprise, it was restored in just three years.
Ciotti and other restoration ecologists are working on more beaver restoration projects with the Maidu Summit Consortium at Yellow Creek in Plumas County and the Nature Conservancy at Childs Meadow in Tehama County. Ciotti estimates there are likely dozens of other smaller projects throughout the state using these approaches.
“It’s gaining popularity quite a bit,” Batt said of the beaver restoration projects. “The federal agencies are starting to move this direction and offer trainings. And then just lots of nonprofits, universities have really gotten on board.”
Why beavers?
Known as nature’s engineers, beavers can change a landscape to cater to its needs better than any other animal after humans.
That’s their advantage against their predators in the wild.
“The beaver on land is like a chicken nugget walking through the landscape for predators,” said Emily Fairfax, Assistant Professor of Environmental Science and Resource Management at California State University Channel Islands. “They’re fat and they’re slow and anything would be glad to have them for a meal.”
But beavers are quick and agile in water, able to protect themselves from predators. They build dams that push flowing stream water over the banks to create ponds and dig canals into the landscape to form an expansive wetland.
In the 1600s, beaver populations thrived in North America, and particularly in the American West, building dams and structuring water systems.
“At its peak, there were about 400 million beavers in the North American continent,” Fairfax said. “Some estimates say that it was like one beaver per kilometer of habitable stream.”
European demand for beaver pelts drove down their population until the early 1900s, when interest in beaver hats and coats died out and the population gradually rebounded. Today, Fairfax said there are roughly 15 to 25 million beavers in North America.
“So they’ve definitely made a comeback, but nowhere near historic populations,” Fairfax said. “And one of the big things that is stopping them from reaching their historic numbers is us.”
How to bring beavers back to a landscape
Beavers and humans like to live in similar places — near water sources ideal for agriculture — so the two species come into conflict. When beavers dam up a stream to make their homes, the ensuing flooding impacts nearby landowners. Or, when people invest in expensive tree-planting projects, beavers may take a liking to those trees and cut them down.
As a result, trapping is a common solution to beaver nuisance.
That’s why the first step to beaver restoration is to stop trapping them and wait for beavers to return.
In some places, beavers may not already be living nearby, ready to jump in and start building. In these cases, restoration ecologists build beaver dam analogs — essentially man-made fake beaver dams.
“We try to design a structure that looks like a beaver dam with the hopes that maybe the beaver will take over, or if not, will mimic the effects of the beaver,” Batt said.
Beavers are native to most of North America, but where there aren’t native beaver populations, Fairfax said, it’s best not to move them.
“I wouldn’t recommend it in a place where there’s going to be a really high potential for conflict,” Fairfax said. For instance, she said, bringing beavers right next to a pistachio orchard would create a conflict for a farmer.
Drought, wildfires
Beaver wetlands are like giant sponges, collecting water from rain and snowmelt during the winter and slowly releasing moisture during the summer and dry periods. As a result, they’re helpful during droughts and against wildfires.
“In my research, I saw it persist for three drought years in a row and then the drought ended,” Fairfax said. “That water can remain accessible year after year after year during drought.”
Fairfax, who published a research paper titled “Smokey the Beaver” about the drought and wildfire implications of beaver restoration projects, said she found evidence of five instances where beaver wetlands stalled the progress of a wildfire including the 2000 Manter fire in California and the 2018 Badger Creek fire in Wyoming.
Wetland vegetation doesn’t turn into the dry, high-risk fuel that feeds wildfires. Instead, the moisture can slow down the wildfire.
“It’s huge when you think about fires in California because time is so valuable,” Fairfax said. “If you can stall the fire, if you can stop it from just ripping through the landscape, even if that beaver pond can’t actually stop the fire itself, just stalling it can give the firefighters a chance to get a hold on it.”
These lush green beaver wetlands also protect wildlife that can’t outrun a wildfire.
“The beavers are creating these patches, these fire refuges that don’t burn anywhere near as intensely,” Fairfax said. “So it’s a relatively safe spot for animals to wait and let the fire pass.”