Short Wave - Why You Should Give A Dam About Beavers!

Episode Date: May 3, 2022

Beavers have long been considered pests by landowners and government agencies. But now, many are starting to embrace them. Today on the show, Host Aaron Scott tells Host Emily Kwong how these furry ecosystem engineers are showing scientists a way to save threatened and endangered salmon and steelhead. Watch the video Aaron filmed with Oregon Field Guide about beavers and stream restoration. For more videos check out Oregon Field Guide.You can follow Aaron on Twitter @AaronScottNPR and Emily @EmilyKwong1234. Email Short Wave at [e-mail]. See pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences.NPR Privacy Policy

You're listening to Shortwave from NPR. Emily, this is the sound of a bunch of biologists going fishing. That sounds super fun. Fishing like with hooks and poles? Not quite. One of the biologists, Gus Wathen, is walking through the water with two poles, yes, but they're attached by wires to a device on his back. It looks kind of like a backpack out of Ghostbusters. And it runs. an electrical current down the poles into the water that stuns the fish. Get them all!

But just temporarily, and that allows the other three biologists to scoop up the fish with nets and drop them in a bucket, or at least in this case, the salmon and the steelhead, the rest of them they throw back. There's our first steelhead of the day, number one. As far as fishing goes, this kind of sounds like cheating, but

I'm guessing these scientists are gathering salmon and steelhead specifically for some purpose. Where did you record this? We're waiting up a small stream in eastern Oregon called Bridge Creek. I was there filming for the nature show, Oregon Field Guide, and this was last August during one of the worst droughts the Pacific Northwest has ever seen. Fields baked and streams dried up or they flowed so hot that the fish died, but you wouldn't know it from the unbridled joy of these biology.

Fish party! Wait a minute. If Oregon was really hot last summer, why is this creek full of fish? Yeah, so Bridge Creek is full of salmon and steelhead today because in the last decade, these scientists have been experimenting with a revolutionary idea to follow in the footsteps of nature's engineer, the beaver. There's some beaver trucks in the mud there. Gus and I climbed up this big beaver dam that's all overgrown with willows and grass and peer out at a huge pond full of cat tails. The impacts that these ecosystem engineers can have to create a wetland is second to none, really.

Beavers as ecosystem engineers, absolutely. But don't a lot of states also classify beavers as kind of pests? Because their dams, while very cool, also flood fields and roads and backyards. Exactly. I mean, historically, beavers have had a pretty bad rap. But now we're kind of in a beaver renaissance. So today on the show, how some scientists learn to stop worrying and love the beaver. I'm Erin Scott. And I'm Emily Kwong.

So into this episode, you're listening to Shortwave, the Daily Science podcast from NPR. So Aaron Scott, I am not kidding you when I say that Team Shortwave has wanted to do an episode on beavers for years. They're incredible critters. They've got orange teeth, dams with actual rooms, tails like tennis rackets that they slap on the water to indicate danger. Not to mention see-through eyelids and two sets of lips. So weird. I mean, I got to admit, I'm obsessed with beavers a bit, Emily. The thing about it is this public appreciation of beavers is pretty new.

I mean, many states still classify them as pests, and that means that people can trap and kill them with few restrictions. And that even happens here in Oregon, the so-called beaver state. But that's because it's hard to stop beavers from doing their beaver thing, which is to build dams, which causes flooding, often in places where humans don't want it. Exactly, which makes it easy to view them as troublesome invaders. But really before the arrival of Europeans, North America belonged to the beavers. Back then, most of the streams looked more like messy wetlands, all just teeming with life and muck. But then European trappers killed most of the beavers, and settlers drained those ponds, plowed the valleys, and pretty much pushed all that water into simplified streams.

So you're saying that our idea of a bubbling brook wending along the side of a flat valley floor, that kind of containment of water, it's a modern invention? Yes, at least in a lot of places. And it can become a big problem, particularly in drier regions, because the streams erode down, digging first a ditch and then, you know, digging deeper and deeper in ravines. And, Emily, this is where we have to step back in time a couple of years. So Oregon Field Guide did a story on the beginning of the Bridge Creek project in 2009. And they met up with Chris Jordan then. He's a fisheries biologist with Noah, the National Oceanic and Atmospheric Administration. And he took them to a tributary of Bridge Creek, where the stream had carved one of these deep ravines into the valley floor.

This is channel incision on steroids. So this is a pretty extreme example. Yeah. I mean, what Chris is talking about here, channel incision, that's basically eroded creeks and ravines, and they're all over the West. But why is a NOAA biologist interested in this creek? So Chris was part of this team working to help endangered salmon and steelhead recover. And, you know, those are fish that hatch inland and they swim out to sea and then return to their birthplace to spawn.

Amazing life cycle, yes. Lovely adventure for a fish, but they're really kind of struggling in large part because of the dams that we humans have built and all the other ways that we've changed their habitat, like logging. And I'm guessing that one of the ways that we've changed their habitat is these eroded streams. Why are these streams a problem for fish that go out to the ocean? Right, Emily. So in really hot, dry years, like when we were there last year, these simple streams just

become too warm for fish to survive. And then during, like, heavy rains in winter and spring, they're way more likely to flood and wash away the fish and eggs. And all of that is because they don't really provide any habitat diversity, anywhere for fish to hide or rest. They're just basically shoots that flush water out of the landscape instead of saturating it as nature intended, which is really more and more a problem with drought and climate change.

Got it. So these eroded streams are bad for a lot of things, namely that they're not providing enough habitat for salmon and steelhead to lay their eggs and begin their life cycle. before they migrate out to the ocean. Yes. So what were Chris and the other biologist thinking about doing in response? And how did beavers get involved?

So this is where it gets a little fun. So the stream restoration playbook at the time was to bring in expensive bulldozers to fill in the eroded areas. But then something caught Chris's eye, where beavers had dammed ponds, the fish were doing better. This is beaver country. The populations are coming back. There's a beaver dam right over here. 2005, there were 300 juvenile steelhead rearing in there in the summer.

And that gave the NOAA team a novel idea. Instead of using bulldozers to restore these streams, maybe they could recruit beavers to do it. I think we're just sort of trying to go back and say, what if there were more beaver? What if they had more stable structures? Would that affect what the stream looks like? The problem is the creeks here are often flooded in the wintertime

and wash away beavers. So the team decided to build a series of starter structures for the beavers by pounding wooden poles across the stream and weaving them with willow branches. And they called these beaver dam analogs or BDAs. The idea was they'd work like a bunch of speed bumps to slow and weaken the stream so that the beavers could then build more permanent dams. That is so brilliant. It's like they're building a beaver home foundation, like pour in the concrete, you know. So... Exactly.

Did it work? So to find out, that's why I was there. I went to meet Chris and Gus at the exact same spot that Oregon Field Guide had filmed with Chris back in 2009 to see how things had changed. The sites are just right downstream. Yeah, that's it. So where Chris had installed the BDA, we actually found an enormous dam that is overgrown with Willow and Cat tails. I don't know. Somewhere in here.

Chris actually did dig through the plants to find the tops of the BDA posts, which are now pretty much completely buried. By beaver excellence. Incredible. Incredible. So the beavers took advantage of those BDA starter structures the bile just set in the stream. They sure did because those BDAs did what they're supposed to do. They slowed the stream enough for the beavers either to build on top of them or to build another damn like five feet away because they're saying, you know, you people don't know us. And it caused a big change, Emily.

There was an eight-fold increase in the number of dams in the study area. Eight times the number of beaver dams. That's a huge increase. How did that change the creek itself? This was really, really cool to see because it's just a huge transformation. All those dams slowed the water, and they backed up the silt, which created this string of pools. And then the beavers dug canals out to clumps of delicious willow so that they could swim back the branches to their lodge. And then that spreads water out even further, which allows more plants to

grow year-round in places that were previously too dry for them. And now, beaver controlled the hydraulics. So really, after just 12 years, what had been this narrow little creek with a little bit of willow running tightly on either side of it had transformed into this wide, dense wetland that's now home to all sorts of plants and animals. What's amazing about this solution is it's actually working in partnership with beavers. And the brilliant thing is, is they do it for free. And we just pay them with some willowed. And it's particularly great in the current drought because you look at these beaver wetlands

and they're really like giant sponges that are just storing water and releasing it slowly out onto the land. I'm getting really hyped on the beaver dams and it's easy to forget what this is really all about. Ultimately, what it will do for our fish friends, right? The salmon and the steelhead. How did this change the creek for that? as a breeding ground. So let's go back to our fishing biologists, and I'll let them show you. Oh, yeah, so should we tag the fish now?

Yeah. After a couple hours of collecting, Eliza Kexey and the team stopped a measure, weigh, and tag the fish. So that way, each fish has an individualized ID, and so we can develop their life history, an estimate, abundance, and then we can also look at survival and production. So in the last decade, after putting in these... BDAs, which coaxed the beavers to build dams. Aaron, what happened to the fish population?

Did it bounce back? It did. As Gus said at the beginning, it was a fish party. The average number of juvenile fish in the study area increased by almost 180%. And their seasonal survival rate increased by 50%. Did this project exceed expectations? I mean, it kind of revolutionized the way that we think about. beavers and caused this seismic shift where, you know, beavers went from pests that we wanted to remove to partners who can help us as we restore ecosystems across the West.

And so it's now so widely accepted that even the government will fund landowners to build BDAs on agricultural land as part of its conservation strategy. Chris Jordan says that there are now hundreds of these projects, not just in America, but worldwide. Wow. Right. And this is what happens when you follow up a decade later on an ecology project. Aaron, thank you for checking in on this creek and telling us what the beavers did to help save the salmon. Absolutely. Thank you for climbing over some dams with me.

And for our listeners who want to learn more, as well as seeing these fishing biologists in action, plus cute beaver footage, we've been promised. You can find a link to the video that Aaron produced for Oregon. Field Guide in our show notes. This episode was produced by Thomas Liu, edited by Stephanie O'Neill, and fact-checked by Margaret Serino. Our engineer was Gilly Moon. And thanks to Oregon Field Guide and Oregon Public Broadcasting for letting us use the footage for this story and to Brandon Swanson for filming it and sending it our way.

I'm Emily Kwong. And I'm Erin Scott. Thank you for listening to Shortwave from NPR. Sorry. I will actually read the line. And I'm Emily Kwong, and you're listening to Shortwave. The Daily Science Pondcast. The Daily Science Pond...

I can't do it. The Daily Science Podcast from NPR. Why'd you make me read that? This is a lot. I think that's the take we're using.