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September 9, 2021 – Drs. Kelly Diehl of Morris Animal Foundation and David L. Anderson of The Peregrine Fund chat about endangered raptors. They talk about birds big, small and ugly (although beauty is in the eye of the beholder), tree climbing, and the dangerous conditions faced by researchers and conservationists. Learn more about this fascinating area of research and how you can help.


The Peregrine Fund -

Dr. Anderson’s TEDxBoise talk on tree climbing -

0:00:11.7 Dr. Kelly Diehl: Welcome to Fresh Scoop, Episode 36, a conversation with Dr. David L. Anderson of The Peregrine Fund. I'm your host, Dr. Kelly Diehl, Morris Animal Foundation, Senior Director of Science and Communication. And today, we'll be talking with Dr. David Anderson. Dr. Anderson is the Science Liaison and Research Coordinator at the Peregrine Fund. He's also the founder and director of the Gyrfalcon Program and has worked with Harpy Eagles and raptors in the Caribbean. So, David, thanks for joining us today.

0:00:43.1 Dr. David Anderson: Thank you very much for the invite, I'm happy to share. It's nice to talk with you.

0:00:47.2 DD: Yeah, it's great to see you. I've known about Dr. Anderson for a long time. I've been at Morris and he's famous around our office, as a wonderful researcher and all-around good guy. So, tell us, before we get into the foundation study, a little bit about yourself and what led you to the Peregrine Fund.

0:01:08.0 DA: Right. Well, I've been studying birds of prey since my Master's degree, and even before my Master's degree, as a summer field technician, working with Swainson's hawks and spotted owls. When I was a Master's student at Boise State University, I was studying birds of prey in Honduras, in the rainforest, and the Peregrine Fund was one of the sponsors of my project, and that was how I got an early introduction to the Peregrine Fund, and they got an early introduction to me. And during that time, they actually asked me to run a field program for them for six months in Honduras, in this really remote corner of Central America; you had to fly, get off on a grassy airstrip in the rainforest and then take a dugout canoe for a day, and the Peregrine Fund was impressed that I could organize all those logistics in a country as rugged as Honduras. And one thing led to another. I was living in Boise, Idaho, working at Boise State University, and had applied for a job at the Peregrine Fund, and I got a call one day, that they wanted me to lead... To actually start and then lead the Gyrfalcon and Tundra Conservation Program in Alaska. So, I started the program and it's been a good relationship ever since.

0:02:29.9 DD: Great. So, tell us a little bit more about the Peregrine Fund and the work that it does.

0:02:37.0 DA: The Peregrine Fund is a really unique organization in the world, because we specialize in the conservation of birds of prey, all diurnal and nocturnal birds of prey, hawks, eagles, owls, vultures, kestrels, and we work all over the world. I don't know how many countries and species we've worked with, but we've worked with Asian vultures in India and Pakistan, vultures in Africa, we've worked in Madagascar for about 20 years, and we have saved some of the most endangered raptors in the world, from extinction, which is another hallmark. It's one thing to say that you work with birds of prey, but we can literally say... Or that you work with the conservation of birds of prey, but the Peregrine Fund can say that, without our being here, the Peregrine Falcon would be extinct in North America, the Mauritius kestrel would be extinct. The Mauritius kestrel was down to four individuals, four individuals, and now it's a stable population on the island of Mauritius.

0:03:46.7 DA: The California condor was down to 22 individuals, and now there are several hundred individuals flying free in California, Arizona, Utah, and Northern Mexico, and we've been essential to that program. And so, it is really neat to say, without us, some of these birds would not exist on the planet anymore, and that when you lose those species, it changes entire ecosystems, to lose top predators.

0:04:13.2 DD: Right, and let's build on that, because this was a question that I had for you, because I don't know. Can you give us a sense of the number of raptor species and how many are considered endangered? You just mentioned some, but do you know that number?

0:04:30.0 DA: Well, the number of raptor species is open to dispute because each organism... A species can be defined in different ways, and some species are split, some species are lumped, but there's about 580 species of birds of prey in the world. I can't tell you how many are endangered, but I can say that, on average, birds of prey are more threatened than other bird groups. There are certain factors of their ecology, that lead them to be more highly threatened or endangered than other groups of birds.

0:05:07.2 DD: Okay. I'm sorry, David. I'm going to ask you to lump because I was going to... Talking about lumping and splitting, is you gave me a nice segue to my next question, which was to expound on what you were doing, which is talking about the dangers these guys face, that maybe people don't realize, in the wild.

0:05:28.3 DA: Well, there are lots of factors that contribute to any type of bird species being endangered. The thing that makes raptors special is that they're subjected to all of those factors. The number one really, is habitat destruction, and it affects raptors disproportionately because raptors tend to be larger birds on average than other birds, and because they are larger birds, they need more habitat to support not only a breeding pair, but a whole breeding population. And as habitat gets fragmented all over the world, it indirectly affects raptors more than lots of other bird species. Another one is persecution; raptors get shot and killed for so many reasons. Oftentimes, it's ignorance. People oftentimes think that raptors kill their livestock, when in fact, maybe the raptors, like Harpy Eagles in Panama hardly ever eat any kind of livestock, but they're the largest eagle in the world. And if you are living on the edge of survival, you've got a few chickens and a few goats, and you see a Harpy Eagle, chances are good that you might shoot that Harpy Eagle to protect your livelihood.

0:06:48.8 DA: But they get shot during migration. There are a couple of bottlenecks in the world, where it's popular to stand on a cliff and shoot migrating raptors as they fly by and they get killed... The list goes on, by poisoning, oftentimes indirectly. Let's say a lion kills some cattle or sheep, in a Maasai farmer's property in Africa, in Kenya, and the landowner or the cattle owner puts poison, he laces poison in the carcass to kill the lion that comes back, but the vultures feed on the carcass and it poisons the vultures. And that's happening in South America with condors as well, the South American Condor, the Andean Condor, is getting poisoned at an alarming rate. When a mountain lion kills a sheep, the farmer puts poison on the sheep carcass, a flock of condors eats the sheep, and the whole flock dies. And then even witchcraft and voodoo is a reason for raptors getting killed. There's beliefs that certain parts of an animal, an owl, a vulture, or a talon provide special knowledge, special powers to the individual and they're used in baptism and voodoo types of ceremonies. And so they're getting killed out of suspicion, voodoo, witchcraft. Every kind of factor that kills birds around the world, all of them are affecting raptors, it's just... It's an accumulation that's hard to bear.

0:08:28.1 DD: Wow, and as you alluded too, this is different than a lot of the songbirds we see, because I think people look at birds and say, "Well, there are a lot of birds, but not these guys. They're really different."

0:08:41.7 DA: Yeah, and raptors exist because they are larger individuals, they usually exist at lower densities than other birds. So, let's just say... Let's mark off 100 square miles of savanna in Africa. Well, 100 square miles of savanna in Africa is going to have a lot more songbirds than it is birds of prey because they require more area to breed, more area to catch their prey and feed their young and... Yeah. And so, when you have a population at low density and you kill a few individuals, if I went outside... I'm not going to do this, but if I went outside my house in Boise, Idaho and killed ten robins because I was a mean guy, it's not going to do anything to robins in Idaho, but if I went outside and killed 10 Swainson's hawks or 10 golden eagles, bam, that's not good, it's very hard for that population to sustain that rate of mortality.

0:09:38.2 DD: Okay. So, we're going to move to your study, but first, I need to talk to you about the subject of your study, which is Ridgway's hawks. So, can you tell us about Ridgway's hawk?

0:09:50.5 DA: Yeah, Ridgway's hawk is a really neat bird. It's related to the red-shouldered Hawk of North America, but it occurs only on the island of Hispaniola in the Caribbean. Hispaniola is the island that has Haiti, the country of Haiti on the west end, and the country of the Dominican Republic on the east end. And the Ridgway's hawk used to be common all across the island in both countries, in all kinds of habitats. It was known to be everywhere, as late as the 1980s. But by the mid 2000s, 2005, there were only about 100 pairs Ridgeway's hawks left in the wild. So more or less, 200 to 300 birds left alive, and they were in a single population in a national park called Los Haitises National Park, in the northeast corner of the Dominican Republic, and they lived in areas that are a mix of farming, agriculture, little, tiny plots like the size of a city block, for example, and then forest. And it became obvious that the Ridgway's hawk was in a really steep decline, that population was tanking, and it looked like without immediate intervention from somebody, the Ridgway's hawk was on a track to extinction. They were going to disappear. They nest largely in palm trees, in the Dominican Republic, and they eat a lot of lizards. For some reason, they like to eat skinks, and they eat some snakes as well. They're really good at that.

0:11:30.7 DA: And then I also want to say one thing about the Ridgway's hawk is, The Peregrine Fund has an entire Ridgway's hawk program, and although I'm the voice of the podcast today, for The Peregrine Fund, there are many people who make this program happen, and I don't want to take any credit away from Thomas Hayes, who was the fantastic field director of the program. His wife, Christine Hayes was the leader of this project that we're going to talk about today, studying the decline of the Ridgway's hawk. There's Marta Curti, who works for The Peregrine Fund. Martin Quiroga and Russell Thorstrom started this program for conserving the Ridgeway's hawk in the Dominican Republic.

0:12:11.3 DD: So, you mentioned the steep decline. Can you tell us why they went into such a free fall, really, it sounds like?

0:12:21.3 DA: Yeah, it was a big mystery because the Ridgway's hawk used to live in all kinds of habitats across the island, they don't specialize in any one habitat, and you can think, "Well, if the habitat is getting... Is being degraded for agriculture, that could explain it," but that's not it. They also eat just about anything, they're a habitat generalist and a dietary generalist, and those species usually are the most resilient to change or to threats. And we didn't know what was happening to the Ridgeway's hawk, and it turned out that, the Ridgeway's hawk was being decimated by a parasite. The parasite is a fly called Philornis PC, they don't really have a common name, that's a scientific name.

0:13:12.3 DA: And the devastating thing, not only biologically, but emotionally for people, is that the adult flies lays its eggs in bird nests, the eggs hatch, the larvae crawl under the skin of the bird nestling, and then they eat the nestling from the inside out. And it's gross, and some of these nestlings would have dozens or even hundreds of these maggots crawling under their skin and it's really harsh. But if everybody in the audience will take a moment to think what that would feel like to be eaten alive by maggots, it's devastating and it's disgusting, and there were so many flies and so many maggots, that very few of the nestlings in the hawk nests were surviving to fledge out of the nest, where they could be safe. They were getting eaten right out of the nests and they would just turn into slimy goo. It was the worst possible death for a bird.

0:14:21.6 DD: And that brings us to your study. So great. So, tell people, because this is what you guys did. And this is really neat, everyone, because it was one of our more athletic studies. So go ahead and tell us what you guys did.

0:14:34.9 DA: Right. What we realized, it was just a hunch. We could see that, Thomas, mainly, could see that the flies were eating the hawks, and hardly any of the hawks' nestlings were surviving. And we had a hunch that it was this parasite that was preventing successful reproduction in the hawk and driving the population to extinction. But science is not about a hunch, it's not about a guess or an assumption, science is about numbers and being able to say with authority, "This is the cause of a decline." Well, Thomas started wondering, "How can we save these nestlings from the parasite?" And he hatched on an idea... Sorry, that pun was not intended, but he hatched on an idea that, as soon as the little nestlings hatched from the eggs, some of these nestlings were dying within two days of hatching, the team of biologists and technicians in Dominican Republic, most of whom are Dominicans, would monitor these nests, and know when the eggs hatched. And then they had to climb these palm trees, which is like a tall pole. Imagine climbing a pole and getting up into the nest, and they would apply a little bit of insecticide to each nestling, and the insecticide is called fipronil, which is the main ingredient in any... Not any, but most of the flea and tick medicines that you buy over the counter. You can go to the local store near you, get this spray and put it on your dog or your cat, and it controls fleas and ticks.

0:16:19.2 DA: We had to get up there within days of the nestlings hatching, and with a syringe, apply a couple of drops to the skin of each nestling and rub it into their skin. But because the nestlings grow so fast, baby birds grow exponentially fast, the team had to return every week, to every nest and re-apply a larger dose of the fipronil, because the original dose of a couple of drops wasn't enough a week later. And so, we had... And I have the numbers here, we had 106 nests that we monitored, half of those were in the control group that got no fipronil, and the other half, so 45-ish or to 50 nests, had to get climbed every single week. Actually, we climbed all of the nests. We had to climb every nest, every week and count how many parasites every nestling had in every nest, of 106 nests for two years, and then see how many parasites did nestlings have, that got the fipronil, how many parasites did nestlings have, that did not get the fipronil, and out of all of the nests, how many nestlings fledged from those nests that got a treatment and those nests that didn't get a treatment.

0:17:41.5 DA: And it was, and is today, one of the most athletic projects the Peregrine Fund has ever had, to have teams of Dominican technicians marching out through the rain forest, climbing nests, spraying the young. And remember that Ridgway's hawks are aggressive, and when a technician is climbing the nest, he's getting bombarded, usually by the female, and she can claw you with her talons and strike you with her fists. It's not easy work. It's not easy work. And we found that the treatment worked better than we could even imagine, and it comes down to the numbers. We found that by spraying, by treating the nestlings with the fipronil, we were increasing the reproduction of this endangered species three-fold. There were three times as many nestlings getting produced, because of our work in those nests.

0:18:39.0 DD: That's awesome. I wanted to ask you about the challenges, though. I think you mentioned some, so that tree climbing, climate, right?

0:18:47.8 DA: Yeah, climate, hot. Yeah.

0:18:49.1 DD: Right. And really unhappy mama birds. Any other challenges? The duration was impressive, just physically keeping that up. But any other, that I don't know about?

0:19:02.4 DA: Well, it's hard to organize a project like that, and Thomas has this really special touch with the Dominican people who live in the communities where he works. And he's got a great relationship, they respect him a lot, and he knows how to coach them on the right way to do the project, the right way to climb the tree. And it took an immense amount of communication and coordination, to get all of these teams working across the national park, to treat the nestlings. So, hats off to Thomas and the crew. And then Christine... Thomas's wife, Christine Hayes, and an Argentinian biologist named Martin Quiroga and I, designed the study, and it worked. The other challenge is, someone who's going to ask this question, "Well, you can't spray nests forever." It's like, "Well, yeah, we can't spray nests forever, but when you have a species that's on the brink of extinction, sometimes you got to do what you got to do." And the Peregrine Fund is famous for that.

0:20:16.0 DA: The Peregrine Fund is famous for stepping into the void and saying, "Without immediate intervention, this species is going away." So, we have... After this study, we found another method, where we can spray the nests only once during the whole nesting season, instead of every week, and if the nest is low enough to the ground, we could even spray it from the ground, through a really long extendable tube, which means you don't have to climb the tree and you don't have to climb it every week. And then we are working on other techniques to save the nestlings from parasites, and we are establishing new populations across the island, because hurricanes hit these islands all the time, and one hurricane could destroy an entire population of birds. So, there are many steps, it's really complicated, saving endangered species, there are many steps and processes involved, and the Peregrine Fund does them all.

0:21:22.8 DD: Yeah, no, it was amazing, reading about this. And you answered some of my next questions, but long-term outcome of the study, you mentioned this follow-up with the spraying the nests. What are people doing right now? What's been ongoing since our part of that, the funded stuff finished?

0:21:45.7 DA: It's important for conservation. Our study on this one fly species and one hawk species is important for conservation because it shows that this fly can decimate a bird population. And in the Caribbean, there are many declining and threatened species that only live on certain islands, like Hispaniola, and it gives a bit of perspective that was lacking before, that, "Oh yeah, not only is this species of parasite common, but it can cause the decline of an entire population." So that lends support to conservation efforts throughout the Caribbean. And I'm not sure if I got to the question.

0:22:32.2 DD: Yeah, no, you got it. Yeah, that was really what I was thinking too, was the long-term consequence. And I think you brought up a really good point that I'm glad you mentioned, which is the... We talk a lot about comparative studies and, "Well, if we learn about cancer in dogs, we can apply it." But I think you've pointed out, there's a lot of comparative work that comes out of just studying a single species. Sometimes, things are unique to a wildlife species, and other times, it has a broader applicability.

0:23:07.4 DA: Yeah, it has a broader applicability. Well said, words well chosen. And this project has a really deep level of satisfaction, because when habitat destruction reduces the size of a population, you don't necessarily have individual birds dying, you just have less habitat, less space for that population to exist, until it shrinks to a point where it can't sustain itself. But it doesn't mean that any bird is suffering. In our case, these birds were suffering. And to alleviate suffering of these little downy nestlings, these little, tiny, helpless, white puffy birds that were dying literally the most horrible death you could want on a bird, kind of feels good.

0:23:58.7 DD: Yeah, no, it's a great study. What's next? What are you guys working on right now, at the Peregrine Fund? What are some of your big projects?

0:24:09.1 DA: Ooh, another big project is the Darien Conservation initiatives. Darien is a rainforest in Central America, it's the border of Panama and Colombia, and it is a really large, intact block of rainforest, but it's starting to get eaten in from the edges, by deforestation, largely for cattle ranching. And in that area, we work with Harpy Eagles. It's the largest bird of prey on the planet, they eat sloths and monkeys. And we want to save as much of this rainforest as possible. We use the Harpy Eagle as an emblem, as an ambassador because they're so charismatic that people want to save Harpy Eagles. Because they're so huge, they require immense areas to preserve a population, and by preserving a population of Harpy Eagles, we're preserving the entire forest and all of the biodiversity in that forest, all of the hummingbirds, all of the orchids, sloths, and giant anteaters, and macaws, and parrots, and everything else.

0:25:26.6 DA: The Darien rainforest is also the home to the native Emberá and Wounaan people. This is their ancestral home. It's a really worthwhile project, and it's just high profile, high visibility, high importance, and it's really near and dear to my heart. So that's one. We've been working in Madagascar for 20 years. We work with the Aplomado Falcon in Texas. It's a critically endangered falcon in the United States. And right now, it only breeds in the far southeastern corner of Texas, near Mexico in the barrier islands down there. So, we just have lots of projects. Of course, the California condor, we have a population that we manage in Arizona. And there's another really emblematic, beautiful, highly threatened species, but there's examples all over the world.

0:26:19.3 DD: Yep. That beauty is in the eye of beholder for those. I'm just saying.

0:26:23.6 DA: They're colorful. They're colorful. Yeah.

0:26:27.0 DD: I've seen some of the Arizona ones. And they're also big. [chuckle] They're really big.

0:26:32.0 DA: Oh, they're big, they're super huge. Yeah. If one flies over your head, it just sounds like a jet airplane just went over your head. They are so loud.

0:26:41.1 DD: Yeah, yeah. They're loud and big, and well worth... They're really interesting. So just as we start to wrap up, what is the take-home message you'd like to impart to our listeners, thinking about there's some veterinarians out there, vet students listening, as well as donors?

0:27:02.9 DA: You know what? Yeah. Here's a take home message. Not everyone is going to work for Morris Animal Foundation, and not everyone is going to work for The Peregrine Fund. But everybody can play a role, because a project like this takes many partners, it takes conservation organizations, it takes biologists, it takes foundations that can contribute money, it takes the expertise of veterinarians to inform our methods, and it takes every individual who's willing to make a donation in the name of conservation, it takes many individuals making those donations, to sum up enough money to support a project like this, that then saves endangered species and has applicability to saving birds all over the Caribbean and all over the world. And everyone can take a little bit of... Just a moment to pat themselves on the back and say, "You too, I too can do something for conservation. I don't have to be a big wig, I don't have to be a biologist, I don't have to go to some of these threatened ecosystems and places to take a stand and do something in the name of conservation."

0:28:12.8 DD: Right, and I think that's really important. So, David, do you have... Give everyone your website address, while they're listening, so they can find...

0:28:20.4 DA: Right, it's Yep. And peregrine is just like peregrine falcons.

0:28:30.9 DD: So, check out what these guys are doing, because they're doing great work, and the foundation has known David for a long time, and I think people forget. We do some bird health work, but it's a little bit different than what you guys do, which is also very strongly conservation-oriented, and health issues, but also conservation, a lot of conservation stuff. And it's really, really awesome. So, David, thanks so much for joining us today. This was so much fun, and I hope you have... We're looking forward to reading more of your work, it's really awesome. And this study in particular, I asked David to come on because they generated so much... I can't even tell you how many good papers came out of this study, the Ridgway's hawk one, and it's just been a really great association. So, I am going to wrap it up and that does it for this episode of Fresh Scoop, and once again, thanks to Dr. David L. Anderson, because David said, there's lots of Dr. David Andersons for some reason, out about in the world. And thanks for joining us, David.

0:29:43.5 DA: Thank you very much and thanks to Morris Animal Foundation for making this all happen, and for sharing the good news.

0:29:49.3 DD: Yeah, and so, everyone, we'll be back, obviously, with another episode next month that we hope you'll find just as informative and fun. The science of animal health is ever-changing and veterinarians need cutting edge research and just folks out there, to learn about animals. And now that's why we're here. You can find us on iTunes, Spotify, Google podcast and Stitcher. And if you like today's episode, we'd sure appreciate it, if you could take a moment to rate us because that'll help others find our podcast in the giant sea of podcasts that's out there.

0:30:21.7 DA: And if you like conservation, make a donation, everybody. Find your favorite foundation and make a donation.

0:30:29.6 DD: Right. And to learn more about us, I'm going to give you our address again. Go to MorrisAnimalFoundation, one word, dot org, and there, you'll see a list of all of our studies and just how we bridge science and resources to advance the health of animals. And you can also follow us on the usual places like Facebook, Twitter and Instagram. So, I'm Dr. Kelly Diehl, and we'll talk soon.