The following transcript is from Season 1, Episode 3 of the Talons of Hope podcast in July 2025 that featured Boise State University alum and Ecology, Evolution, and Behavior Ph.D. candidate Michael Henderson speaking about his gyrfalcon research.
Munir Virani (Host of Talons of Hope podcast, Chief Operating Officer of the Mohamed Bin Zayed Raptor Conservation Fund): Hi everyone and welcome back to Talons of Hope, where we explore the frontlines of raptor conservation and the people dedicating their lives to birds of prey. I’m your host, Munir Varani, and today we’re heading to a very special place: North. Very far north, to the windswept tundras of Alaska. Joining me is Michael Henderson, a field biologist and researcher at The Peregrine Fund and now a PhD candidate at Boise State University. Michael didn’t grow up with wildlife in his backyard, but discovered his calling on a construction break when he took a chance on science and never looked back. Michael’s journey is one of grit, cliffs, and curiosity, from rappelling into golden eagle nests to now leading groundbreaking research on gyrfalcons, the Arctic’s apex raptor. With support from The Peregrine Fund and the Mohammed bin Zayed Raptor Conservation Fund, Mike’s work is unlocking how climate change, prey shifts, and diseases are reshaping the fate of these iconic falcons. Today we’ll hear about what it is like to study gyrfalcons in one of the most remote regions on Earth, how their survival depends on prey like ptarmigan and ground squirrels, and what their changing world tells us about our own.
Michael, welcome to the show.
Michael Henderson (Ecology, Evolution, and Behavior Ph.D. Candidate, Boise State University): Thank you for having me. I’m excited to talk today.
Munir Virani: Let’s start with your story. You didn’t grow up in a world of wilderness. What flipped the switch from construction to conservation, and how did raptors capture your imagination?
Michael Henderson: I think it was a curiosity to understand the world around me. I started taking science classes and really started getting into ecology and the interconnected nature of wildlife and humans, and I was really fortunate to get the opportunity to work with raptors through the Raptor Research Center at Boise State University. I just fell in love with raptors. Their tenacity, the way they live their lives, has been very influential to my life, and I just fell in love with getting a better idea of what it is that makes their lives go well and what I can do to kind of make sure and protect them for future generations to enjoy them the way I’ve gotten the chance to do so.
Munir Virani: You’ve rappelled into eagle nests, and now you hike across Arctic cliffs studying gyrfalcons. You just came back from your field study site on the Seward Peninsula. What is it about working with these birds that keeps you coming back?
Michael Henderson: I mean, just on the surface level, I love being out there, you know, the adventure of finding these nests and trying to figure out how to get into them and get these blood samples. And you know, like I was saying, I love these birds. I get a ton of motivation from seeing them in nature. And I really want to make sure that they’re going to be around, that they can be protected for future generations to take that excitement and take that motivation and, you know, make sure that they’re here for the long haul.
Munir Virani: Gyrfalcons are among the most specialized raptors on the planet. What makes them so unique and also so vulnerable, especially in Arctic ecosystems?
Michael Henderson: Yeah, so they’re a really cold-adapted bird. So they’re the largest falcon in the world. So that larger body size allows them to, you know, survive those long, cold winters in the Arctic. They’re actually one of the few bird species that can survive year-round in the Arctic. They’re also able to put on a lot more fat than other bird species. They have really dense feathering. All of these things make them really ideal for surviving cold weather. But the Arctic is experiencing climate change at least three times faster than the rest of the world, meaning that their habitat is getting warmer and getting wetter over time. And it’s likely that that’s going to be maladaptive for a cold-adapted bird like a gyrfalcon.
Munir Virani: As the climate continues to change, what does this mean for the future of birds like the gyrfalcon?
Michael Henderson: I mean, that’s ultimately what we’re trying to figure out, right? We’re trying to really dissect those different avenues through which climate change can impact gyrfalcons. And like you said, it’s, you know, changing predator-prey dynamics, changing disease ecology, and changing weather patterns. So we really have to, you know, use really good science and rigorous statistics to parse out exactly what is happening now and what’s going to happen in the future.
Munir Virani: Michael, some of your early work showed how nest protection, like overhangs, improves productivity and reduces stress on adult falcons. Can you explain what that means and why it’s very important in a changing Arctic?
Michael Henderson: Yeah, so we see that higher temperatures and more precipitation make it more likely that nestlings are going to die just from being exposed to these weather patterns. And by simply having an overhang or protections on either side of the nest that block wind and blowing rain, those nestlings are a lot more likely to survive. And one of the main things that drive population dynamics—adult survival is really critical and probably the most important thing—but also nestling survival, because those adults have to replace themselves in the population. And a lot of conservation efforts happen at that juvenile level. So if we can just naturally, you know, by adding nest protections, we can produce more nestlings that can ultimately help the population dynamics and hopefully help prevent any further population declines.
Munir Virani: Let’s talk prey. You’ve studied gyrfalcon diet using stable isotopes and cameras. Maybe you can state briefly what stable isotopes are and then lead into what gyrfalcons are eating and how that’s shifting with Arctic climate change?
Michael Henderson: Yeah, so dietary stable isotopes, it all kind of comes back to “you are what you eat,” right? Each different prey item, whether it’s a squirrel or a ptarmigan or a fish or, you know, depending on the species, they all have a different isotopic signature. So that’s the ratio of normal isotopes of carbon and nitrogen versus heavy isotopes of carbon and nitrogen. And by looking at those ratios in the prey and then the blood samples that we get from the gyrfalcons, you can get an idea of what proportion of each prey type they’re taking.
And some of the things that we’ve seen is that throughout the season, you know, gyrfalcons historically have always kind of been considered a specialist for ptarmigan. And in the winter, that’s undoubtedly true. It’s the only real prey species out there during the wintertime. But during the summertime, their diet breath expands out a lot and they start taking a lot of other prey. And in our study area, the big one is ground squirrels, especially towards the latter part of the breeding season. When juvenile squirrels emerge, they become the dominant prey type for gyrfalcons. We’ve also seen that weather affects which prey species they’re likely to take, which when it’s been raining for several days or it’s really hot for several days, that the squirrel activity increases and they become more likely to be depredated by gyrfalcons. And kind of the thought with the changing predator-prey dynamics is that ptarmigan, so that’s rock ptarmigan and willow ptarmigan, those are essentially arctic specialists as well, and they’re under those same climate change factors as the gyrfalcons are. So it’s likely that their population sizes and their distributions on the landscape are likely to change and it may change in a way where there’s less overlap between where the gyrfalcon cliffs are, where they can breed, and where the ptarmigan are. So our goal in the research is to understand how adaptable those gyrfalcons are going to be if the ptarmigan populations go down. Are they going to be able to switch to alternative prey species and still be successful, or is being disconnected from their primary prey, those ptarmigan, going to be extremely detrimental to them?
Munir Virani: Mike, we now know that disease risks are rising in the Arctic. What are some of the new threats that gyrfalcons face in terms of pathogens and parasites? And how might warming temperatures be reshaping that risk?
Michael Henderson: Yeah, so we’re seeing throughout the Arctic that there are new diseases coming in, and that’s not just affecting, you know, gyrfalcons and raptors. There are muskox diseases and moose diseases that are coming in and kind of wreaking havoc on those populations. And the main issue with gyrfalcons specifically is they evolved up in the far north where it’s cold, where most pathogens can’t survive and reproduce and transmit between individuals. But as these temperatures warm, they’re able to, you know, complete their life cycles throughout the Arctic. And, kind of anecdotally, gyrfalcons are thought to be really susceptible to diseases that are really common in more temperate areas, but not in the Arctic. And most of that information is taken from falconry birds and captive birds that are kept in areas that are not in the Arctic. So a couple of the big threats, I think, are avian influenza. So the Arctic, you know, brings millions of migratory birds from around the world. And so AI outbreaks can happen anywhere. They all congregate up in the Arctic and it creates kind of a petri dish to allow these diseases to transmit. And we’ve seen in Iceland that around 2021, they had a big AI outbreak and their population declined dramatically in a very short amount of time, which really makes the threat of disease maybe the most problematic and the most important for kind of immediate conservation. A lot of the threats of climate change are kind of long-term—you know, weather changes slowly, prey dynamics change slowly—but one disease outbreak can really be extremely detrimental to a population.
Another disease that I’m particularly interested in is avian malaria. That’s another one that something like a gyrfalcon tends to just die when they get it. A really high mortality rate compared to, like, a peregrine falcon that oftentimes has the immune response to deal with that disease and move on. The gyrfalcons just have a tendency of just dying very quickly from it. And at least in the state of Alaska, we’re seeing that avian malaria is able to complete its life cycle at basically the same latitude as our study area. So we’re actually this year starting an effort to trap and test mosquito populations right around our sites to see what species of mosquitoes are up there because different species have a different carrying capacity for avian malaria. And we want to test whether or not those mosquitoes actually have it. That gives us a much bigger sample size, a much bigger umbrella to test a lot of samples as opposed to, you know, a handful of gyrfalcon samples that we can have a year. So we’re really interested to see how that turns out.
Munir Virani: Your study is in the Seward Peninsula in Alaska. Do the results of your study kind of mirror what’s going on with gyrfalcon populations in other parts of the circumpolar region?
Michael Henderson: I think in certain aspects, absolutely. You know, temperatures are rising throughout the Arctic. So anything regarding temperature, disease, things like that, I think are directly attributable to other parts of the range for gyrfalcons. I think the one thing that’s different is diet. Not, you know, ptarmigan are essential for gyrfalcons everywhere they are, but some populations like Iceland take a lot of seabirds and that could be, you know, a greater risk factor for things like avian influenza because those seabirds could be carriers for it. So I think a lot of our research is directly related to global gyrfalcon conservation, and we also really aim to collaborate with those people around the world. So we’re trying to collaborate with Greenland and Iceland in particular, and like I said, Iceland’s experienced a big population decline and Greenland is seeing a possible decline as well. They’re not seeing as many gyrfalcons as they used to see.
Munir Virani: A recent study that you co-authored shows that gyrfalcons prefer territories with high densities of willow ptarmigan and Arctic ground squirrels. How critical are these prey species and what happens as their distributions change?
Michael Henderson: I mean, in our study area, absolutely essential. I mean, that is fundamental to the survival of gyrfalcons, I think. When you start looking at other areas of the gyrfalcon range, I think the, you know, a lot of them don’t have ground squirrels, so that alternative prey species might change. But it’s likely that the willow ptarmigan habitat is pretty similar throughout their range. So knowing what that habitat looks like and being able to identify that and protect that, I think, is ultimately protecting gyrfalcon habitat and helping to make sure their population can stay around.
Munir Virani: Tell us about the field experience. What’s it like studying these falcons in places like the Seward Peninsula? Give us an example of the hardest day you’ve had in the field and also the most memorable.
Michael Henderson: Well, it’s amazing. It’s hard. Every day is a bit of an adventure. You know, particularly in the beginning of my fieldwork, none of us really had much experience out there. So a lot of navigating and trying to find these cliffs and find these birds on the cliffs. We’ve gotten ATVs stuck in, you know, four feet of mud. We’ve flipped over pack rafts. We’ve found cliffs that got the best of us where we weren’t able to get in. I feel like there are a lot of great memories up there. Some of my favorite, honestly, oftentimes involved the people. So I worked with Dr. Travis Booms at Fishing Game, Alaska Department of Fish and Game. And some of my favorite memories are sitting in a nest with him and banding gyrfalcons on a beautiful sunny day and, you know, receiving mentorship. And then a couple of years ago, I was working with Cara Beer, who is our crew lead right now. And I got to kind of experience the same thing from the other side, where I was the one mentoring and we’re still sitting in those same gyrfalcon nests, banding nestlings. And it was just a really great kind of full-circle moment and really made me appreciate the work we do and the impact we have on researchers and hopefully mentoring the next, the next generation of raptor researchers.
Munir Virani: And I want you to describe to me what went through you for the very first time, what you felt when you for the very first time held a wild gyrfalcon in your hands.
Michael Henderson: Oh, it was amazing. I felt, I felt special. I felt undeserving to an extent, you know, like how many people get to do this? And just, I felt honored, I guess, to have the opportunity to say, how many people get to do this? How many people get to hang off a cliff and get to see this very intimate picture of how these gyrfalcons live and get to know their behavior and kind of their personalities? And they are fun, kind of goofy, sometimes aggressive, birds, you know? You see a wide range of behaviors in them, and it’s a real treat and a privilege to get that point of view.
Munir Virani: The Mohammed bin Zayed Raptor Conservation Fund is now supporting the work not only in Nome, Alaska, but also in Patagonia. How important are these global collaborations to building a future for Arctic and Southern Hemisphere raptors alike?
Michael Henderson: They’re essential. I mean, we need buy-in from as many collaborators that we can get. And before the Mohammed bin Zayed Raptor Conservation Fund, there was the Species Conservation Fund, which was really essential in just getting this project started. We had to get a truck up there, we had to get housing, we had to get equipment, and they were essential in making all of that happen. So yeah, and we have collaborators within the U.S. as well, Boise State University, Cornell University. And it really takes a full team of folks to dissect these effects of climate change and help protect these birds because we all have our specialties and in order to really look at the picture holistically, you really need a team of folks from around the world that have diverse skill sets.
Munir Virani: Looking ahead, what is your vision for the gyrfalcon research program? What do you hope your work will achieve for science, for conservation, and most importantly, for the next generation of Arctic researchers?
Michael Henderson: I think the main thing is understanding how climate change is impacting, you know, raptors more generally, but gyrfalcons specifically. Studying climate change is really complicated, you know, climate change affects kind of the baseline driver of ecosystems, and it affects species throughout the ecosystem in a lot of complicated ways that interact with each other. So it takes a lot of work and rigorous data collection to really parse these things out. So my hope is that we can better understand how gyrfalcons and raptors more generally are going to be impacted, not just in the Arctic, because the Arctic is warming a lot faster, but the rest of the world is going to catch up to where the Arctic is now. So by gaining an understanding of what’s happening in the Arctic now, we can be better prepared for how climate change is going to impact raptor species around the world. Specifically, with our program, one of the chapters of my PhD is looking at how weather is affecting community dynamics, and in order to get that data, we have about 20 years of helicopter survey data, so that’s about 550 sites that we do twice a year. And ultimately, we want to figure out exactly what it is that is being the most impacted. Is it adult survival? Is it juvenile survival? Is it new competitors, like more peregrine falcons coming in, and really identify the most important big-picture drivers of population change? Because there are some signs that gyrfalcons are declining within our study area. So we want to see, you know, what is the mechanism? How exactly is that happening? And once we’ve identified that, then we start designing mitigation. We design, you know, further research projects. So my hope is that that’s going to guide the future direction of our program.
Munir Virani: Fifteen years ago, right here in Boise, Idaho, there was a big gyrfalcon and climate change and ptarmigan conference. A lot has changed, obviously, since then. Do you think it’s time to have another conference, to have all these polar researchers come together to discuss their findings?
Michael Henderson: Absolutely. That’s something a collaborator, Stephanie Galla at Boise State, we were just talking about this a couple of days ago, that it would be a great idea to get everybody back together. We know so much more than we did back then, even though, you know, a lot of the really great data came out of that. And that was really the motivation behind this whole program, like identifying how adaptable gyrfalcons are to climate change came from that conference. And so it would be fantastic to be able to do that again. I think that’s something we should strive for.
Munir Virani: Can you imagine a world without gyrfalcons?
Michael Henderson: I don’t want to.Munir Virani: Michael, thank you so much for sharing your enthusiasm and your passion about your work in Alaska. In the vast and silent reaches of the Arctic, the gyrfalcon stands not just as a predator, but as a sentinel of change. Through the eyes and data of people like Michael Henderson, we begin to understand how even the most remote ecosystems are telling us stories that we just cannot ignore. Michael’s work reminds us that science isn’t just about charts and numbers. It’s about passion. It’s about persistence and climbing cliffs, sometimes literally, to protect what matters. The Arctic may be thawing, but thanks to researchers like Michael, the resolve to understand and conserve it remains stronger than ever. This has been Talons of Hope. I’m Munir Varani. Until next time, may your heart stay wild, your vision sharp, and your wings ever rising.