Science Friday - How Conservation Efforts Brought Rare Birds Back From The Brink

Episode Date: September 19, 2025

The overall state of birds can seem rather grim. Almost a third of North American bird species are in decline, and in the last five decades, more than 100 species have lost over half of their populations. This is primarily due to lack of food—fewer insects to eat—and habitat loss, like the development of grasslands. But there’s a bright spot: Some birds that were once rare are now abundant, like the merlin, sandhill crane, and pileated woodpecker. Host Ira Flatow talks with biologist Tom Langen, who explains these birds’ remarkable comebacks, and discusses his conservation work to bring threatened fish species back from the brink. Guest: Dr. Tom Langen is a professor of biology at Clarkson University.Transcripts for each episode are available within 1-3 days at sciencefriday.com. Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

Hi, this is Ira Flato, and you're listening to Science Friday. Today on the show, the story of how once rare birds became abundant in North America. Some of the things that we do to try to conserve wildlife really do work. The overall state of birds is nothing to chirp about. Almost a third of North American bird species are in decline. And in the last five decades, over 100 species have lost over half of their population. That's primarily due to lack of food, fewer insects to eat, and habitat loss. But there is a bright light within all that darkness.

Some birds that were once rare are now abundant, like the Merlin, Sandhill Crane, and pilliated woodpecker. Joining me now to explain these remarkable comebacks, which he recently wrote about in the online news site The Conversation. And his conservation work to bring threatened species back from the brink is Mike. guest, Dr. Tom Langen, professor of biology at Clarkson University in Potsdam, New York. Welcome to Science Friday. Thank you, Ira. I'm happy to be here. Nice to have you. Okay, let's start with the Merlin. Before we get into their decline and rebound, for our listeners who are not familiar with this bird, can you can give us Merlin 101? Sure. A Merlin is a falcon. It's about the size of a pigeon. It's not a large falcon, but it has that typical falcon shape.

It feeds on birds, so it's primarily a bird hunter. Formerly, it was most sort of associated with the remote areas of Canada, the boreal forest. It's an interesting falcon because it doesn't build its own nest. It nests in other birds' nests, and in particular nests in old crow nests, or sometimes active crow nests where it chases the crows out and takes over. Wow. Wow. Okay. I know the Merlin has an icon of call. We have a recording of that. Let's listen to that. Wow. You know, I think I've heard that but did not know it was a Merlin. You know, it's often people will contact me and say, what is this bird I hear flying over my house?

There's two of them. And they have this call. And I know immediately what they're talking about. It's really striking. When you hear it, it draws attention. Wow. So what's the Merlin story? How did it go from rare to abundant? So when I was a kid in the 1970s and started watching birds, I mean, I had to go up to northern Minnesota to see one. At that time, they bred mostly in the boreal forest of Canada and Alaska in North America. They're also in boreal forests in Eurasia. But in the 1970s, A few pairs started to breed in the town of Winnipeg, Manitoba, and Canada. And the population seemed to start growing about the time that DDT was banned in Canada and the United States and certain other pesticides as well.

And these falcons, like a lot of top predators, were very sensitive to DDT. and the elimination of that in the environment, they started having better breeding success. And at the same time, they started adapting to villages and towns, first in the prairie provinces of Canada. And then starting really in the 2000s, they've spread across eastern Canada and the northern U.S., and they continue to spread. They're now breeding in Columbus, Ohio, and down the Appalachian chain, as far as, is North Carolina. So really a tremendous increase, in part because of a cleaner environment, less pesticides. But also in the 20th century, they were one of the species that were often shot by people, particularly during migration, their migratory birds. And in places like what is now

Hawk Mountain Reserve, people you would line up and shoot Merlins, Peregrine Falcons, and other hawks, particularly bird-eating hawks. Wow. I don't know why anybody would do that. It's like they thought it was sport? Well, some thought it was sport. Even some of the early naturalists had this really hard to understand mentality that while they should protect many birds, including many hawks, those that ate other birds were somehow criminal or, you know, beyond the pale.

And so there were naturalists that encouraged shooting falcons because they were bird killers. No kidding. Okay. Let's move on to one of my favorite birds. Ever since I saw many years ago a giant shoebox size hole in a tree, right? I'm talking about the pilliated woodpecker. Yes. And it's been quite a while since I've seen one. I'm talking decades. Give me an overview of what's happened to them, their fall and their rise again. So by the early 20th century, particularly with the cutting of most of the eastern forests and the big trees, but also because of shooting as well, for some reason people like to shoot pillated woodpeckers, apparently, there was a very serious decline. And by the middle of the 20th century, pilliated woodpeckers were mostly only found in really large, dense, old forests. places like the Adirondacks or the Alleghenies or the Smoky Mountains. But in large part because of the regrowth of forest in eastern North America

and the protection of trees, even in suburban and urban areas, and those trees getting larger, plus pretty much a change in culture and laws that prevented shooting, these birds started to come back. And as they came back, they started to move. into suburban areas and even urban areas. Like the Merlin, there's a behavioral change. And whether it's because they were no longer being shot at or otherwise persecuted, or also because they've learned or evolved to be less shy around people, they've moved into urban, suburban areas where there's large trees. So they just did this on the run. I mean, no one made any accommodations for

them, they learned how to adapt. They did. Yes. When you read the naturalists in the 20th century, they talked about how these birds were very shy and they would not fly out in the open or fly over open areas to get from one tree to another. And that changed. They're now willing to go into people's backyards and feed in their bird feeders, whereas a couple of other woodpecker species, the imperial woodpecker and the ivory-billed woodpecker didn't adapt. and they're now probably extinct. Yeah, we've heard a lot about that. I've rebuilt Woodpecker.

Let's talk about the next rebound success story. And I mean the Sand Hill Crane. What does a Sand Hill crane look like for those of us who have never seen one? They are quite striking, right? They are. In part, they look a little bit like a Dr. Zeus kind of bird. They're tall. They're kind of have a long neck.

They're brown and gray, but they have a... a very striking red cap. They have a long beak. Their young are actually called colts because they kind of have that spindly leg walk like a horse colt. They're social birds, at least in the non-breeding season. They form flocks, sometimes enormous flocks. There's places where thousands and thousands, for example, in Nebraska, tens of thousands of birds aggregate.

But in the 20th century, cranes were really mostly remaining in remote areas of Canada and Alaska and some of the Western states. They had almost disappeared from the Eastern United States, the Midwestern United States, and Eastern Canada. Because? Two reasons. The main reason was the drainage of wetlands. So removal of wetlands for agriculture in the 19th and 20th century removed the areas of in which they nested and fed, but also they were also heavily shot.

So these people call cranes. They still call them ribeye of the sky. They also can damage crops. They eat seeds and nuts, and they like corn, and they'll feed on corn. Like after it's planted, they'll feed on the seed. And so people persecuted them and probably most importantly drain their wetlands. So now they're back again. Why was that? Did they bring the wetlands back?

Yeah. So a big part of that is the return of wetlands. So in the 20th and the 21st centuries, there's programs to take areas that are marginal farmland and return them to wetlands, which they were formerly. Moreover, we have laws now that prevent continued drainage of wetlands, right? We have a no net loss policy in the U.S. And that's been effective. So cleaner water and more habitat has helped. And I think most people, when they talk about the loss of birds and the biggest success stories is the return of the bald eagle. Yes. Right?

Yes. And so the bald eagle is another success story. And, you know, it's incredible how rapidly eagles recovered after the elimination of certain pesticides. from the environment like DDT. For example, in my state in New York, there was a program to hack young eagles, basically to raise them so that they would fly off and hopefully stay, which they did.

But those programs have ended because the eagles are doing populations continue to spread. It doesn't mean that there aren't some things in the environment that are problems for these birds, but they have essentially recovered and are even found in places like around New York City now.

Yeah, yeah, I've seen them in Central Park places like that. You know, now that you mention we talk about the bald eagle, I notice that all the birds on your list are big birds. I don't mean the big yellow one on Sesame Street, but does that play a role in their resilience? That's a great question. They are all large, and, you know, I would have thought as a conservation biologist,

and I mean, we think of as conservation biologists, that these large birds are probably the most vulnerable, right? They reproduce more slowly. They require more habitat and so forth. So these are the birds you would expect to be the most vulnerable to extinction. But it's something about in these particular species, their ability to recover and the ability for people to pay attention, I think, and care and implement conservation programs that to protect them, that they've been able to bounce back.

And the fact that they're big, people notice when they're missing. They do. People notice it. People care about it. And they certainly get excited when they see them. And I think that that excitement, that passion, that also helps to bring support for conservation. All the birds on my list are birds that people tell me about, even if they're not really

birders, but they see them and they're excited to see them. hear them in their landscape. We have to take a break, and when we come back, how to engineer a solution to protect threatened fish species. So you can build basically an artificial stream around a dam with flowing water and structures, with the hopes that the fish can swim up it from one side to the other or down it. Let's pivot just slightly to talk about some conservation work that you're doing, not with birds, but with threatened species of fish, the moon-eye fish.

What are some of the challenges of tracking the moon-eye fish? I don't think I've ever heard of a moon-eye fish. Yeah, the moon-eye fish is interesting. It's a silver fish. It even looks prehistoric, kind of. It has a big eye, big silvery scales, and its most distinctive thing is it actually has teeth on its tongue. It has teeth on its tongue.

teeth on its tongue and the family that it is in are basically translates as the tooth-tonged fish. And they've disappeared from many of the rivers and streams that we know that they formerly existed on. And in my area, there's a noticeable population in only one river. And then they call the Oswagachi and then maybe also in the St. Lawrence River. So we're trying to figure out why they seem to have gotten rare. And the first thing was to figure out, are they indeed rare or just people have not reported them. And we found that they're very difficult to find. We've searched and, you know, we've catch them, but they're difficult to find.

They're very sensitive when you handle them. You have to be very careful or they die. Are they a migrating fish like a salmon? Yes. So they don't go to the ocean like salmon, but what we do think is the case is they move up and down river. So they go to sort of waterfalls and rapids to breed. in the early spring.

Then they go out to deeper water in the summer. So they move back and forth and dams create barriers that prevent them to going to places where they want to go. This happens with lots of riverfish. This is an issue with salmon with American eel and others.

And the moon eye is probably another. Now, I've seen salmon cannon where they actually shoot the salmon over the dam. Are they doing that with the mooneye? No, no. That's a, that's a drastic solution and they do that in a few places, but that's not generally what's done. What fisheries biologists are trying to do is to create fish passageways. So you can build basically an artificial stream around a dam with flowing water and structures,

with the hopes that the fish can swim up it from one side to the other or down it. And so one of the things that I and my colleagues are doing are looking, are looking, looking at the design of those kinds of fish passages. Because when you put a fish passage like that, if the water is moving too fast, the fish aren't strong enough to move through it. There may be other things that prevent them from going because there's no cover. So we're interested in how you put rocks and other kinds of structures in a fish passage. So fish feel comfortable and are able to move through that passage structure to get from one part of the river to another.

So you're a fish engineer, fish passageway engineer in your spare time. Yes, well, I am the biologist, but I work with some civil engineers who know the engineering part. So I provide the animal behavior. They provide the engineering design and we work together. So they're engineering a fish-only lane in the river. That's exactly right. It's essentially what it is. Yeah.

What can we learn in summing up from these conservation success stories? I think we can learn two things. One of them is that some of the things that we do to try to conserve wildlife really do work, right? We really can't have success stories. Sometimes we hear so many discouraging stories that you get the feeling, well, maybe nothing really will work. You know, there's too many people, too many environmental stressors. But we can find that in some cases, we can identify the problem. We can come up with solutions, implement. them and they actually do work. I think the other is that, you know, there's probably many other species that if we think about it, we can design structures like fish passages or manage habitats in ways that we can live with nature. Very good way to wrap up, Tom. I want to thank you for taking time to be with us today. Very interesting stuff. Thank you. It's been my pleasure. You're welcome. Dr. Tom Langen, Professor of Biology at Clarkson University. that's in Potsdam, New York.

Hey, thanks for listening. If you have a comment or question or a story idea, our listener line, it's always open. Call 8774 SciFRI. 877, the number four, side fry. This episode was produced by Soshana Bucks Bow. Lots of folks helped make this show happen this week, including John Denkoski, Danielle Johnson,

Beth Rami, Jackie Hirschfeld. I'm Ira Flato. Thanks for listening.