Evolutionary Biologist Scott Taylor And Birds

0:28On Planet Money, we have covered a lot of topics. It's a stressful day at your office, or maybe your room turned into an office. You want to get away from the sounds of notifications, meeting alerts, Zoom calls. You step outside for your lunch break. No matter where outside is for you, anywhere in the world, you'll likely hear birds.

1:21That was a morning dove, a cardinal, a chickadee, a hermit thrush, and a common loon. Birds. We think we know them, what they usually look like, what makes a bird a bird, where they come from. They're everywhere, after all, but less so now than in the past. What if we know less about birds than we think? What if we could learn more about them with a bit of intentional observation, and in the process, maybe learn something about ourselves and what we need to do to keep them around for decades to come? Scott Taylor joins us after the break for a chat all about birds and answers your questions. He's a professor at the University of Colorado Boulder's Department of Ecology and Evolutionary Biology and the director of the university's Mountain Research Station.

2:06He's also host of the new science podcast, Okay, But Birds, it's out now. I'm Jen White. You're listening to the 1A Podcast. We'll be back after this short break. Stay with us.

2:21on wait wait don't tell me it's not so much we get to talk to celebrities it's that we get to talk to celebrities about other celebrities like we did with actor nathan lane i remember having to tell george c scott that i was leaving the show to do this musical and he said to me you're leaving me to do a magic show listen to wait wait in the npr app or wherever you get your podcasts Scott, welcome to 1A. Thanks so much for having me. Super excited to be here. Okay, so Scott, what's one species you study that you suspect most people don't know much about? Well, I study black-capped chickadees, which I feel like people would recognize, but maybe not know all the really cool things about them.

3:03Okay, give me a cool thing about them. Yeah, so black-capped chickadees, they're non-migratory, so they spend their winters with us in North America, and they're only about 10 grams. So you can imagine if you're a tiny little thing that needs to maintain a warm body temperature over the winter, you have to have some really cool strategies to do that. And they've evolved these really amazing spatial memories. So an individual black-capped chickadee, as the winter approaches, can hide, you know, tens of thousands to hundreds of thousands of individual seeds that it's collecting from your bird feeders maybe, and then recall the individual locations of those over the winter to survive, which I think is, as someone who loses their keys quite regularly, pretty impressive.

3:41And how do they stay warm in colder climates? Yeah, I mean, they run a body temperature a little bit more than ours. Their feathers obviously act as really good insulation for them, but they really just have to keep eating so that they can generate the heat they need to stay warm. So if they forget where their food is, that's a problem. How are scientists like you observing how birds adapt to climate change? We're seeing more severe weather events, temperatures getting hotter or colder in some places. how are birds adapting? Well, it depends on the species. For some of the migratory species, we're seeing shifts in when they show up on their breeding grounds in an attempt most likely to align, you know, when they're having their chicks with when there's a lot of food available.

4:25But for some species, even though it looked like they were adapting, now there's offsets between when they're showing up and when food is available. And we're seeing pretty large die-offs of chicks, which is unfortunate. You know, in many places, bird populations are just declining and it's seems like it has something to do with that mismatch between the environment and food availability and what the birds are doing. In other cases, we're seeing rain shifts. So, you know, if you live in Southern Ontario, Canada, like where I grew up, there are certain birds we see there now regularly that, you know, I would never have seen as a kid.

4:58And it's because they've kind of expanded the Northern edge of their range as, as winters have become less severe and less harsh. So, you know, the cool thing about birds is they can fly. So they can, they can respond to climate change pretty rapidly, but when it's a food-related thing, it's harder for them to adapt. What are some other examples of how human activity is changing life for birds? There are many. I mean, you could start with, you know, probably you've heard of avian flu or H1N1. That influenza virus is the product of human farming practices, and now it's circulating the globe and impacting bird populations more than probably any other virus ever has in the history of wildlife, not just birds, which is crazy to think about.

5:44You know, we reduce habitat, and I think a common thought is, well, birds can fly. They can go to the habitats that's still available, but one has to remember there are also birds there. So as we reduce habitat, you know, cutting forests and developing agricultural lands, we're seeing reductions in populations because of that. So generally a lot of negative things, unfortunately. We're making it harder for birds out there. Well, in one of your later episodes, you talk extensively about bird flu. Let's listen to a little. Remember when bird flu sounded just like a bad tabloid headline? Avian flu, specifically the highly pathogenic kind known as H5N1, isn't just a farm problem anymore.

6:24It's not confined to chickens in crates or duck farms in the Midwest. It's in wild birds, in raptors. It's even in mammals. It's rewriting ecosystems to a degree that we do not fully understand, and in some cases, it's devastating entire colonies of seabirds in just a single season. Okay, but how did avian flu get here? Where is it going? And how worried should we actually be? It started quiet, as these things often do. A few dead geese in southern China in 1996. The virus was labeled H5N1, another entry in the alphabet soup of influenza strains. But this one, this one was different. It didn't just make the birds sick, it wiped them out.

7:03And within a year, it had made the jump scientists always dread, from bird to human. Now, Scott, you spoke to a bird flu expert during that episode. What more did you learn from her? Yeah, it was really amazing to talk to Nicola and just hear more about the actual impact. So I think one thing, it's hard to understand how much of an impact bird flu is having on wild bird populations, because actually measuring how many birds have died is an incredibly difficult task. And she brought up the fact that citizen scientists have played a critical role in our understanding of where bird flu is impacting wild populations.

7:38There's many ways for folks to report observations of dead birds, and that's actually helped us understand what's going on and where it's happening. I think a point she also brought up and that I alluded to already is, you know, we think of bird flu as this problem of wild birds, but the reality is bird flu only evolved to be as virulent as it is because we kind of created a petri dish in the way that we farm poultry. And, you know, where there are no costs for this flu to be highly virulent when you have many, many hosts, and those hosts are genetically very similar, as often is the case in our, you know, kind of farming operations, you can create these viruses that then spill out into nature and would never have evolved naturally but are out there now and circulating.

8:21and that's, you know, it was interesting to think about. She also brought up that there are certain waterfowl now that show resistance, which is good. You know, it's great when resistance to viruses evolves, but it also means now we have like typhoid married ducks flying around, spreading this virus that can infect about 170 different species of birds in North America have been impacted by bird flu. So as I said, you're an evolutionary biologist. Your podcast is called Okay, But Birds. What led you down the path of studying birds specifically? Yeah, that's a great question because when I first started out kind of being interested in nature, I was definitely observing birds but way more interested in amphibians.

9:02When I went to grad school, though, I wanted to study specifically hybridization, so when two different lineages interbreed and produced something as it was kind of mixed up between them. And I knew that from my work as a naturalist that birds were engaging in hybridization relatively frequently. So as a graduate student, I went to South America and worked on blue-footed and Peruvian booby hybridization, which was really awesome. And I've just kind of worked on birds since. From an evolutionary perspective, birds have a genome that's only about half the size of a human genome. So when we want to sequence whole genomes and look at variation and understand all these questions about evolution of birds, it makes it a little bit more affordable as well, which was kind of a nice add-on.

9:41Well, and you study hybrid zones in your research. What is that and why is it important to look at when it comes to things like climate change? Yeah, so hybrid zones are regions of the landscape where you can find hybrid individuals between two different lineages. And so you could think of, I mean, the word hybridization is mostly, it's familiar to most people, I think. And often people think of like a mule, which is a cross between a horse and a donkey. And mules, we generate them, we make them because they're really strong. but they're also sterile. So there can be costs to being hybrids. In the bird hybrids I study, there are problems with the hybrids.

10:19The chickadees in particular have reduced spatial memory, which as I alluded to, that's probably not good for survival. And in the context of the chickadees, we study hybridization and hybrid zones to look at how fast birds can respond to climate change. So yes, they can fly and they can move around, but we've been tracking the hybrid zone between black capped chickadees, which are in the north, and Carolina chickadees, which are in the southeast, as it moves northwards. And you can predict where it is based on minimum winter temperature. So they really are responding fast. And that hybrid zone is moving at about a kilometer and a half a year, which like birds are almost the only organisms that could respond that fast to climate change, right?

10:58Like the trees they're using or the salamanders under the rocks in those forests just can't disperse that fast. And so I think it's interesting to see how quickly certain species can respond to climate change and then quite sobering to realize most species cannot respond that fast, but they might need to in order to survive. Well, let's listen to more of your podcast. In this segment, you're discussing the idea of bird monogamy. Okay, but is bird monogamy just PR? We've all heard the line, they mate for life. It shows up in wedding toasts, on fridge magnets, and a suspicious number of greeting cards.

11:33Swan necks forming a heart, penguins in formal wear, lovebirds doing PR for the idea of soulmates. Many birds do form pair bonds. They share a territory, build a nest, raise chicks together. But across the avian world, extra pair copulation, the scientific term for stepping out on your mate, is very common. In some species, a third or more of the chicks in a nest may have a different father than the one tirelessly bringing in food. It's less storybook romance, more Maury Povich, you are not the father with feathers. So why bother with a pair bond at all if exclusivity isn't guaranteed? When does a pair bond hold tight?

12:08And when does it flex? And what are the birds actually optimizing when two individuals decide to build one nest? Okay, Scott, so maybe killing the dreams of people who were rather attached to bird monogamy. Why did you want to focus on this? I think it's just such an interesting, you know, birds, like you said, are everywhere and we think of them and we kind of humanize them in a way that I don't think is super helpful for understanding how cool the world actually is. And so this bird monogamy episode, I talked to Dr. Carrie Branch from Western University. And I think it's, you know, birds have these complicated lives where social monogamy makes a lot of sense because raising chicks is easier when you have two individuals.

12:47But as we talk about in the episode, genetic monogamy is actually very, very rare, even among these socially monogamous birds. And there's lots of interesting reasons for that, whether it's because someone has a better song or brighter colors or some other characteristics that you might want to see in your offspring. There's lots of different reasons for, as we call it in the podcast, stepping out on your mate. Let's go back to our voicemail. We got this message from Sarah. I live in the Chesapeake Bay watershed area and one of the interesting conversations we're having about birds is in relation to the rise, replenishment of bald eagles and the effect that's happening on local osprey populations.

13:29A lot of watermen are convinced that it isn't fishing that's depleting osprey populations, but the increase in bald eagles in the area. It's kind of an interesting take on how environmentalism has effects beyond what we sometimes understand. Thanks for that message. I'd love your response to what we heard there, Scott. Yeah, I think it's a really interesting observation that bald eagle population increases, which have been really exponential since DDT was banned. Prior to DDT, bald eagle populations just kind of tanked, and there were very few breeding pairs in the lower 48, and now I see them on my way to work every day.

14:08And yeah, bald eagles are large predators that have impacts on other birds in the ecosystem. It should point out that osprey also declined because of DDT and have rebounded since then. And I think when I hear thoughts like that, It's hard to know what was the baseline before we changed everything anyways, right? So yeah, there are a lot more bald eagles now, and they probably have impacts on osprey and great blue heron nesting and so on. But all of them have increased since we banned DDT, so I think that's probably a positive. And understanding how those two species interact is maybe something we need to focus more on.

14:43Carla in North Arlington, Virginia writes, To be honest, I've never paid attention to birds until I converted my front yard to a native garden. Wow, the birds. I work from home and almost immediately got to see how quickly our yard was filled with birds while my neighbor's yards looked relatively empty. And Melanie in Ohio asks, can you talk about the impact of planting non-native species and what impact it's had on birds? What do you think, Scott? Yeah, so both of those are great points. And I think it is true with birds, again, because they can fly. If you build it, they will come to your yard.

15:15If you plant native trees, if you plant native bushes that produce berries, if you have all of the things that they need. And the main reason that they respond so quickly is because those native plants provide food for native insects. And one of the interesting costs we've seen of planting non-native plants, so trees we might think are very beautiful but are not from North America, they have very few insects that eat them. And so then there's very little food for birds. And there was this really amazing study by a colleague, Desiree Narango, when she was a graduate student, looking at what are the consequences for local bird populations when you have a lot of non-native vegetation.

15:51And the breeding success, she was studying Carolina chickadees, I believe, and the breeding success of those birds was a lot lower in neighborhoods with more non-native species of trees because of their subsequent impact on what insects were available for those birds to feed their chicks. So there's all these kind of indirect costs of planting non-native tree species. And certainly we're going to have an episode about how can you build a yard for a bird later in the season. And there are a lot of amazing things you can do. And you can imagine, like, if everyone did that to their yards, that's a ton of habitat.

16:22You know, I think people don't realize that cumulatively across the city or whatever, you could create a lot of really amazing bird habitat just by being a little more thoughtful about what you plant. Let's take a quick pause here. Before we do, let's hear this message we got from one of you. Francesca writes, there is so much we can do on an individual basis. Birds need habitat, food, and shelter. Our yards can supply these. Leave your leaves where birds find bugs to eat. Plant native plants. They attract bugs for birds. Keep your cat indoors. Better for the cat and saves birds from painful and unnecessary death.

16:57With the elimination of my lawn, I have gone from 8 to 18 breeding species in my suburban backyard. We can do this. Still to come, Scott's tips for bird watching and why the hobby seems to show up more frequently in popular culture. We'll be right back.

17:17Today's discussion is for the birds, all kinds of birds. Let's get back to it with this message we got from one of you. Hey there, my name is Brandon Van Grift, and I'm from the songbird capital of the United States, Louisville, Kentucky. I've been in love with bird watching since I was a young child. I can remember sitting in the backyard with my great-grandma and my mom, and they would just know every bird they saw and every song they heard. and it inspired me to start my own business called Bird Brains. It's a one-of-a-kind service that installs, maintains, and fills bird feeders in your backyard so that you don't have to.

17:54I really enjoy this. I've only been doing it for a couple years, but I've really been able to help people connect with nature and build a community around backyard bird watching. Brandon, thanks for that message. We also heard from Guy in Pensacola who says, 20 years ago, I built a bird nest platform in a tree in my yard. I have a great horned owl pair nearly every year, and it is a great source of enjoyment. I love hearing them and enjoy watching the young ones grow up. I recommend this to everyone. Scott, here's a simple foundational question that might touch on the ideas many of us have about birds.

18:31What makes a bird a bird? What makes a bird a bird? That's an excellent question with not a very straightforward answer, actually. I mean, for a long time, we thought that birds were the only creatures that had feathers. And then the fossil record showed us that there were dinosaurs, not the lineages necessarily that evolved into birds, but that also had feathers. So there's no one character, but all contemporary birds have feathers. And so that's the thing you can really rest your hat on. They also have beaks instead of teeth, although so do turtles. So that doesn't only, you know, not a unique thing to birds.

19:05And then some of them have the wishbone, which, I mean, we just had Thanksgiving. Maybe some people have a wishbone or a furcula drying out somewhere to pull apart at Christmas. That bone is unique to birds, but not all birds have them. So, you know, feathers are the thing to focus on, but some other neat characters as well. Well, you see plenty of birds in your work as a naturalist. When you're looking for birds, when you're noticing them, what goes through your head? I just really like spending time with other creatures. I think that's been true for me since I was a kid. I spent a lot of time just wandering in the woods alone thinking about nature.

19:43And I don't know, birds, like you said at the top of the episode, like they're everywhere. You can be in the middle of New York City and you can observe these really different and interesting creatures that can fly and have all these interesting natural histories. And so I just like watching what they're doing, whether that's foraging or interacting with one another, or maybe you get lucky enough to see one grabbing nest material. I just think they're such fascinating creatures, and that's, yeah, birds are cool. I don't know. Fun to watch. Well, we're getting lots of questions. Here's another voicemail message from Lisa in North Dakota.

20:17And I just wanted to say some good news that I see here in North Dakota is the bald eagles that we have along the river. Yesterday I was cross-country skiing along the Missouri River and saw 10 different eagles in a short distance. And today on my drive home, I saw two additional bald eagles. It's really great to see all that beautiful bird life along with the geese along the river. Lisa, thanks for that message. What are some bird species to start with, either because they're easier to spot, Scott, or they're closer to high-population areas? I think, yeah, if you start out in your yard, American robins are in most places, even in cities, as long as there's some trees and grasses.

20:57But you could just start out with pigeons. I mean, pigeons are these underappreciated, amazing creatures that we've brought with us all over the world, and they have really cool behaviors. So depending on where you are, if you have a little bit more natural habitat, American robins, black-capped chickadees, downy woodpeckers or hairy woodpeckers or northern flickers should be around. But if you're really in an urban area, just start watching pigeons, and I think you'll gain a better appreciation for just how cool they are. We got this question from Robert in Cincinnati who emails, I'm curious about flocking behavior and specifically murmurations, as I've heard it called, where flocks make complex shapes in flight.

21:34How do birds decide to do that? How do they not hit each other flying so close? Do certain species of birds tend to do that more? Scott, what can you tell us about that behavior? Yeah, I mean, it's a beautiful and amazing behavior to witness if you ever get a chance. Murmurations are specifically in reference to European starlings, which were introduced to North America a long, long time ago, and are actually doing quite well here but have declined in Europe. Not all birds travel in these large flocks. Flocking behavior is really an anti-predator behavior, so the more targets there are to hit, the less likely it's going to be you kind of thing.

22:10That's why we see schooling behavior in small fish, same thing. I don't know a lot about the physics of flocking behavior, but I know that although it looks complicated, like it looks like there are these coordinated movements, It's really each individual bird just has very brief responses to the bird beside it. And then that in like accumulated across the flock creates these amazing coordinated movements. But it's not very complex, I think, from an input perspective. That's my understanding. I know there's been some work both in birds and in schooling fish to that degree. But very cool to watch if you can find one.

22:44Well, I have a question. So in my community, I think they're a type of hawk, but they fly and they just sort of follow the air drafts. And I'll stop sometimes if I'm out walking and there may be a dozen of them just sort of flying. Do birds fly for pleasure? Because when I watch them, I'm like, it doesn't seem like they're hunting. They just seem to be enjoying the draft. And I know that's probably me projecting onto the birds, but do we know if birds fly just to fly? I don't think we know the answer to that question. I think what you're seeing are probably turkey vultures. They're these large black birds that will kettle, and so they use thermals, and they'll just float on kettles.

23:32And they actually are looking for food in a very kind of slow way. turkey vultures use their sense of smell, so they're just floating around waiting until they catch the scent of roadkill, and then they would go towards that to eat it. There are some birds that engage in what we consider play behavior that's not flying. So ravens and crows and other corvids have been recorded sliding down a roof on their back in the snow, which there's no reason to do that, and it looks kind of fun. And I think because it looks like something I would want to do when there's snow. We consider that more of a play behavior, but I don't know.

24:08If I could fly, I would definitely fly for fun, although it is very costly from an energy perspective, so maybe only if I'd had a lot of food. How do you actually classify a species of bird, defining where one species ends and another starts? Oh, man. Yeah, that's, what is a species is such a complicated question. You know, the kind of classic definition of what one species is versus another is that they're reproductively isolated, so they can't reproduce and create offspring. But then we just talked about the fact that birds hybridize, so that complicates it. For me, if birds can hybridize, but there's some problem with those hybrids, maybe like in the chickadees I study, their memory is impaired or their metabolism is impaired, so they're more likely to not make it through a winter or something like that.

24:54I would still consider the black caps and Carolina chickadees to be different species, but it's blurry. And a lot of my work focuses on those blurry spots where you have hybridization, and it's harder to define exactly what a species is. But mostly people think about reproductive isolation. Well, we're getting questions about feeding birds. Lynn emails, please talk about whether it is good for birds to have a backyard bird feeder. Some experts advise against it. And Eli writes, my mom is really interested in pileated woodpeckers. In general, what I want to know is how can I attract more birds to a feeder?