We can't just leave it to beavers: how we can improve the success rate of beaver restoration
Beavers can restore degraded ecosystems and improve drought, flood, and fire risks. But we can't just drop off beavers into new places and expect them to survive. Here's what we need to do.
Let’s Nerd Out About Gardening is a twice-monthly publication for curious people who love to nerd out about gardening, farming, and nature. Come nerd out with us researched-backed deep-dives and thoughtfully curated articles delivered straight to your inbox:
Dear Gardenerds,
In the early 1950s, the Idaho Fish and Game department airdropped over seventy beavers into the Chamberlain Basin in the zaniest beaver relocation ever.
Parachuting beavers wasn’t their initial plan. After WWII, people had discovered the beautiful and beaver-filled McCall and Payette lakes. With human clashes rising, and knowing the benefits beavers bring even back then, the Fish and Game department wanted to relocate the beavers rather than trap them. And they had the perfect relocation spot — Chamberlain Basin.
There was just one problem. The Chamberlain Basin was in the middle of the No Return Wilderness Area, far from any sort of human infrastructure, like roads.
They tried to use packhorses to carry the beaver cages, but neither beaver nor horse appreciated that idea. Beavers need to keep cool, dry, and unstressed — and that wasn’t happening on top of the constantly spooked horses.
That’s when state biologist Elmo Heter decided to try something absurd — parachutes. Tons of parachutes remained from the war effort and he was able to buy them cheaply.
The real problem came with the cages. Since there wouldn’t be humans around to release the beavers upon landing, he needed something that the beavers could open themselves. He first attempted using woven willow cages, which the beavers could gnaw through. Unfortunately, they could also gnaw through them while on the plane.
Instead, he developed a wooden box that would open upon impact. To test the box, he got the aid of an older male beaver Heter called Geronimo. Geronimo wasn’t injured in the tests, and his reward was to be the first relocated beaver, along with three young females.
(Some articles play this out to be so kind of harem fantasy, but beavers are monogamous. He did have a better shot at finding a mate with three options.)
But while the program was successful (and economical), beaver relocation and reintroduction isn’t as easy as grabbing beavers from where you don’t want them and moving them an area where you do.
Relocations face such challenges as:
relocated beavers are immediately vulnerable, as there’s no structures to protect them from predators (whose populations are also rebounding),
solitary beavers will swim hundreds of miles to find a mate, abandoning the chosen site altogether,
badly degraded rivers and overgrazed riverbanks lack trees for beavers to build with,
degraded rivers are too fast for beavers to build in,
beavers have minds of their own (and humans aren’t that great yet at predicting what is suitable habitat), and
humans. Always humans.
Thankfully, biologists and conservationists have come up with ways to smooth over these challenges.
Do we even need to relocate beavers at all?
Here’s the thing that vexes all of us — beavers have a mind of their own. They’ll build a dam flooding a parking lot. They’ll leave a “perfectly good” selected site. They’ll even just start reintroducing themselves into rivers and streams with no human help whatsoever. All they need is the right conditions, and they’ll return themselves.
So do we even need to relocate beavers at all?
No, and yes. In an ideal world, we’d simply set up the right conditions for beavers to reintroduce themselves to our target sites, using most of the suggestions below (only one is specific to relocations).
But in our actual world, land owners and managers want to get rid of encroaching beavers, whether by killing or by relocating them. While it’s better all around to mitigate problems with beavers than to relocate them (a good site is a good site, and beavers will keep moving in), relocating beavers at least means they have a chance to survive and selected sites can get beaver attention quicker.
5 Ways To Improve Beaver Restoration Outcomes
Build beaver lodge analogues in chosen sites before beavers are released
On an established site, with a lodge and beaver pond, beavers are pretty safe from predators. They build their lodge entrances underwater so they can leave and enter without being detected. They raise the water level to increase their foraging range. When faced with a predator, beavers don’t fight — they run for water.
But often, we’re relocating beavers to damaged, shallow streams. They don’t have any structures to hide in and the stream is often too shallow to provide adequate cover. A 2002 study on the success of transplanted beavers in Wyoming [PDF] found that 30% of reintroduced beavers died within 180 days due to predators, with 8 dying within seven days of release.
So the Methow Okanagan Beaver Project in Washington found a solution: build a fake beaver lodge. The beaver lodge analogues are much simpler than what the surviving beavers will eventually build, but it provides immediate shelter.
Protect riverbank trees from overgrazing by reintroducing predators or fencing off riverbanks
Yellowstone Park had a big problem. In the 1930s, native wolves were extirpated from the park to allow deer and elk to proliferate. After all, that’s what people want in a forest, right? The ability to hunt.
Well, it worked. Elk and deer proliferated, gobbling up young cottonwood, willow, and aspen shoots along the riverbanks. The rivers eroded.
Turns out, wolves are another keystone species. In 1995, the park reintroduced wolves. The trees rebounded and the beavers returned. Weirdly, Yellowstone Park reports that even though today the elk population is three times larger than what it was in 1968, the willow stands remain robust.
But we don’t necessarily need to reintroduce wolves. We just need to prevent grazing along riverbanks, especially when replanting saplings, and we can do that with temporary deer fencing. We just also need to be okay with beavers snapping up the saplings we replanted.
Match beavers with mates before releasing the pair into the wild
If you’ve ever been lounging near a beaver pond, you’ve probably been startled by the silence-shattering slap of a beaver tail. Beavers slap their tails on the water to warn other beavers of predators. The system is pretty good, as the tail slap can be heard at quite the distance. Nearby beavers can run and dive under the water.
A single beaver is vulnerable to predation. They have no one else looking out for them. It’s also very difficult to set up a beaver dam, lodge, and find food all by one’s self.
And even if the single beaver survives, beavers will swim for hundreds of miles in search of a mate — and they’ll probably find better territory along the way.
Unfortunately, it’s not always possible to relocate beavers in family units. That’s why the Methow Beaver Project set up a beaver dating service. When single beavers arrive at their converted fish hatchery, they sex them and set them up with eligible beavers. Not just any beaver will do and it can take weeks to find a suitable match, if at all. Beavers can only remain so long at the facility before they begin to lose their wild instincts.
Once matched, the beaver couples are relocated as a pair to a beaver lodge analogue. The pair have each other to look out for danger as well as build and forage, and neither will need to leave to search out a mate.
Building beaver dam analogues (AKA post assisted wood structures) to start slowing rivers
Incised rivers run too fast. That’s one of the reasons why we want beavers to move in: to slow the water down. But as great engineers as they are, they’re still rather small mammals. Beavers struggle to build dams against the flow of swiftly moving water. When the river surges from snow melt or rain, whatever parts of the dam they’ve managed to erect will blow.
So Michael Pollock and ecologist Nick Bouwes devised a solution. They would temporarily “dam” the river until beavers could take over. While they first investigated hiring contractors to build a dam, the quotes were often prohibitively expensive. “The bids were coming back at fifty thousand dollars for one structure,” Bouwes explained in Ben Goldfarb’s Eager. “I’d just gotten done building a log home for that much.”
That’s when Bouwes found a thriftier solution: a hydraulic fence pounder. They could just pound logs into the stream. The logs would start slowing down sediment. It was backbreaking work, and challenging as well dragging it over rivers, but it worked. They installed 121 Beaver Dam Analogues (BDAs) and beavers returned, turning the analogues into real dams. By 2013, beavers had constructed 115 dams, fortified 60 BDAs, and even built dams outside their planned area.
Where the word “beaver” is staunchly divisive, advocates call the BDAs the benign “post-assisted wood structures.” Still, it can be difficult to get approval to build either.
Getting buy-in from local humans
But the biggest challenge isn’t even beavers or local habitat — it’s humans.
Whether it’s nearby people and managers not wanting beavers on their land, trappers trapping recently relocated beavers, local people destroying beaver lodges and dams, or state regulations banning beaver relocations outright, the biggest challenge that conservationists face are often humans.
Beavers are controversial, and while there’s many people who recognize their value and inherent worth, there’s many people with a hair trigger tolerance for beavers.
(Admittedly, it’s easier to support beavers when they’re not flooding half your property or cutting down the prized apple trees your grandfather planted.)
The truth is — the amount of beavers that an area can support isn’t actually the natural limit. It’s the cultural carrying capacity: how many beavers the people living there can tolerate.
And that is what the next instalment covers — how can we coexist with more beavers?
💬 Join the Conversation
Do you have a beaver reintroduction project nearby?
Have you seen beaver dam analogues in the wild?
Am I missing any beaver reintroduction improvements?
Share with us in the comments! We’d love to know.
Happy growing!
Tanith (she/her)
I am writing this and garden on Treaty 4 land, the traditional home of the Nehiyawak, Nahkawe, Nakota, Dakota, Lakota, and Métis nations.
P.S. Here’s your extra credit reading!
Ben Goldfarb explains the ins and outs of beaver reintroduction and relocation in his fabulously informative book Eager: The Surprising, Secret Life of Beavers and Why They Matter (Bookshop.org affiliate link). When I picked up this book, I’d only hoped for some more beaver facts to fill out my essay on why beavers are essential to the Plains. Reading his book inspired me to go so much further. Most of what I’ve learned is thanks to him. If you want to learn more about beaver restoration, read this book!
BC Wildlife Federation, in collaboration with First Nation communities and other organizations, launched The 10,000 Wetlands project, using beaver dam analogues to restore beavers to 8 sites across British Columbia.
wants to know why the British government is backpedaling on legalizing beaver reintroductions in the UK, even as he can see the benefits in his backyard (literally).The Methow Okanagan Beaver Project in Washington explains their process for relocating beavers. While they aim to promote coexistence with free consultations (as more beavers will just move in), they offer relocations as a last resort. They’re looking for potential relocation sites, so contact them if you happen to have property there.
California took a big step forward for beavers in California with the passing of Assembly Bill 2196 in September 2024. The Maidu Summit Consortium with the California Department of Fish and Wildlife reintroduced seven beavers to their ancestral land in 2023, with help of 10 years of advocacy work by the Tule River Tribe, who reintroduced beavers to their land in June 2024.
Samantha Wright explains how the parachuting relocation project worked, including diagrams of the beaver dropping box. The Times shows the recovered footage of the program.
While fencing can be an easy solution for keeping grazers out of healing riparian zones, they can be extremely dangerous for wildlife if done in the wrong way. That’s why Montana Fish, Wildlife & Parks published a handy PDF guide for landowners for creating wildlife friendly fences. Just be mindful that the guide has graphic depictions of the worst case scenarios.
If you found this article interesting (and since you got to the bottom of this email, it’s extremely likely that you did), please forward this email or share via social media with the Gardenerds in your life. As they say, sharing is caring. 💖
This is undoubtedly the most unique article I'll read today, so thank you for that!
Wow! Parachuting beavers and a beaver dating service. You always include such interesting details. Thanks!