Richard Prum on Birds, Beauty, and Finding Your Own Way | Conversations with Tyler

Hello everyone, and welcome back to Conversations with Tyler. Today I'm talking with Richard Prum of Yale University. I spotted Richard in the field some while ago and classified him as great American ornithologist. Richard, welcome.

Thank you. Great to be here.

Why is there so much infidelity in Australian birds in particular?

Well, you know, I don't think that there probably is an extraordinary amount of infidelity in Australian birds. However, there are certainly a number of classic cases of the investigation of multiple mating in Australian birds. The classic case being the fairy wrens, which have a very weird social system including one feature, which is multiple mating.

And how well can we explain why fairywrens are different in their mating practices? Right? How much explanatory power does ornithology have there?

We need to talk a little bit about what makes fairywrens extraordinary in other ways. Fairywrens live in cooperative groups, extended families that include multiple males and females of reproductive age. And usually a large number of them are the, at least male male offspring of previous years that are hanging around helping mom and dad or some adults raise their relatives. This probably arises, and it's very common in Australian birds, it probably arises because of very high habitat variability, in particular variability in rainfall. As you see already, thinking about Australia, we think a lot about, you know, that's a drought or not, right? So under those conditions, you never really know whether you're gonna have enough resources to raise kids. Another feature is that the habitat is rich and in some times of the year, and so as a result, they're kind of packed cheek to jowl. So there's no real estate for the kids to go off to. So they stay at home, move into the basement, and help their parents, right, until they can inherit the back 40 or take over a bud off, if you will, into a new territory. So that means there's a lot of reproductive opportunities between groups, but the groups are in separate territories. So a lot of what happens in these cooperative species like fairy wrens, as people found out, is that the females mate multiply. And that is, they can mate with other members of the group besides the mature or most dominant male, or they can mate with other males in other groups.

And is it variability of rainfall that makes Australian birds weirder?

Well, there are two cool things about it. One is that, yes, and people have associated cooperative breeding, this special variation in the avian family life where you get cooperative behavior among reproductive age individuals, with unpredictable rainfall. So that's a general phenomenon. You find it a lot in different parts of the world.

How does the equilibrium work there? So rainfall is unpredictable, and then what happens? Solve for the equilibrium, so to speak.

Yeah, sure, sure. So rainfall is unpredictable, and also the other combination is the habitat is saturated, right? So there aren't a lot of places to go. So what that means is that it's often more helpful or more useful for individuals to delay dispersal until their reproductive age, and then they're hanging out, and then of course they do work. And why— how they benefit is— could be both helping their relatives, kin selection, or that they could be gaining experience, you know, direct benefits like learning how to raise a family before they get a chance to do their own.

Is it the case that birds are more modular in construction than mammals? For instance, they don't seem to use their wings and legs so much in concert the way mammals might. Or is that not true?

Well, that's a really cool thing. Actually, if you go back to the gait of a crocodile or any tetrapod, the front legs and the hind legs were really coupled, right? And you have to do that well. Going back probably in the very long bipedal theropod dinosaurs, long history of bipedality in theropod dinosaurs, those things had to be uncoupled. And it required a lot of rewiring, both of the motor movement, the brain, the muscles, et cetera. So that's ancient in the lineage of birds. Think of T-Rex with its tiny little forelimbs, very decoupled. What birds have done in flight is actually to couple the forelimbs with the tail in flight. So we have a part of the axial skeleton, right, which now becomes in a way related to the flight apparatus, which are the forelimbs, right, the front of the wings. So that's a lot of— like, it basically turns out to be deep dino biology that birds are just taking advantage of in flight.

Here's a very stupid question. The intermediate steps towards the evolution of flight, why are they efficient? So I go through life, let's say I didn't have a car. I've never woken up and said, gee, I would love to glide today, right? Gliding serves no purpose for me. So how is it we get to flight in between, right? Why did that persist?

Yeah, you know, deep controversy there. There are lots of careers that have been thrown on the pyre of avian flight origins. But in detail, there are two theories. One is the ground-up cursorial theory that somehow you're running and you're running fast enough and you start with maybe movements that help you manipulate as you run and then finally take off the ground. The other is the arboreal theory or the trees down that you start with gliding and controlled movements. Of gliding and then eventually to powered flight. Those folks have been warring at it for, you know, well, almost a century, but really going at it for the last few decades. And so where does this sit now? The interesting thing is that it used to be that the origin of birds was like a menu where you had Column A or column B, and column A was birds are not related to dinosaurs, feathers evolved for flight, and flight evolved from the trees down. And then the opposite was birds are dinosaurs in column B. Birds are dinosaurs, feathers evolved for thermoregulation or for something other than flight, and that flight arrived from the ground, or flight arose or evolved from the ground. And it turns out that the dino people were correct. Feathers did not evolve for flight, and birds are dinosaurs. It turns out that column A was actually right about flight. Flight most likely evolved from the trees down, and there's a whole bunch of reasons why, starting with gliding like a flying squirrel, and then controlling your gliding, and then using those controlled movements to create a flight stroke.

But flying squirrels are not that plentiful, right? They're not taking over the world. They don't seem to do that well.

Yeah, they sure as hell are taking over Borneo, I can tell you. I don't know if you've been, but you go into Southeast Asia, there are there are forests where there are incredibly diverse gliding mammals of multiple families, right? So that's probably because the forest is made mostly of dipterocarps, which look like really, really, really high broccoli, you know, 30 meters high, and so there's a lot of space. And why are they flying, or why are they gliding? Well, to get away from predators, or even ultimately they get good enough at it that they can use it to disperse from tree to tree. So the idea is that that's how it started. And of course, maybe one of the reasons why flying squirrels haven't taken over the world is because they never got to powered flight like birds did, which obviously is going a lot further.

Now according to Jennifer Ackerman, duetting of song occurs in about 16% of bird species. How well can we explain the cross-sectional variation there?

Well, you know, a lot of explanation in biology is historical explanation, and so I don't think that comes out in a regression line, but One of the things we see is, again, social complexity. In tropical birds, you're much more likely to have pairs that endure for the whole year, right? And resident on a territory, that kind of long-term social relationship will support duetting.

Is it the migratory birds that have lost duetting?

Yeah, well, most of the birds that are That are— well, duetting is still highly concentrated in just a few groups, songbirds and, you know, and a few other lineages. So there's a lot of things like gulls and penguins and shorebirds that don't have duetting per se.

But if you were carving up how much of this universe of duetting is explained by historical persistence and path dependence as opposed to theory, what would your proportions be?

I don't know, but I'd have to say, you know, a large amount of it, 30%, 50%, is history because a lot of these groups originate, like Australian birds. One of the interesting things, all of songbirds are out of Australia, right? They persisted there for a very long time, so there's a lot of lineages with lots of female song and some duetting, complexity in Australia and then a few, very few lineages that came out of Australia. And that kind of long history in a place means that, you know, you're likely to keep something like that or not have the opportunity or reason to change it.

Putting path dependence aside, if you were trying to give us the most fundamental explanation of why sexual dimorphism is different in birds compared to mammals, What would that be?

Hmm, well, that's actually a really big, a really big question.

Of course.

Well, it's a big question.

But the most fundamental factor, what is it?

Yeah, the most fundamental factor is that most birds don't have a penis.

And talk me through the equilibrium there.

Well, there's a lot there, so that's where we start. Most birds don't have a penis, which means that one of the things that happens in avian evolution that's distinct from mammals is that the kids require a lot of care, but they also have to— they're growing up in the nest, right? They're hatching out of egg, but they're very, very vulnerable until they can fly. So birds have a very rapid period of rapid development, and that means that they grow up and leave the eggs, and you need two parents to do that efficiently in most diets or most kind of ecologies. That means the dad's gotta be at the nest, right? And so we usually thought that female birds are— or that we usually thought that you have social monogamy, at least two birds helping raise the young, because the young are so needy and they have to grow up quickly. But there's another possibility, which is that they could evolve to be so needy and grow up quickly because they managed to get males at the nest. And one of the things that happened, you know, in the phylogeny of birds, you've got ostriches and their relatives, then you've got chickens and ducks, and then you've got the rest of birds. And that's a bunch, that's the vast majority of them. And in that lineage leading to the rest of birds, the penis evolved away. And the question is why? And my own theory is that female birds preferred mates that did not have a penis and one of the ancillary benefits of that, one of the correlated benefits of that is that they were no longer subject to sexual coercion. They could be— or sexual violence. They could be coerced behaviorally but they couldn't be forcibly fertilized and that means that they have freedom of choice. And what do they do with their freedom of choice? They choose beauty. And so one of the reasons why birds are so beautiful is that males don't have a penis. So they have to be subject to choice in order to affect reproduction. And also, they have to invest if females require it.

Now sometimes albatrosses don't breed until they're 20 years old or even on average, maybe it's what, 10 years old? What are they doing in the meantime that's so important?

Yeah, well, that is a deep question. I actually have a student working on delayed maturation. What are they getting better at?

Right?

Because life history theory tells you that you could never— there's no upside to delaying reproduction for— if all things are equal, but they must be getting better at something. A lot of people think it's foraging, right? That raising that one young on an island and foraging hundreds of miles miles out of the ocean then returning, and this whole social relationship to raise an albatross family is tough. And so being efficient enough to raise— may take years to develop. You gotta get good at foraging before you can raise a baby, and certain diets certainly require that. And we have the same thing in many gulls, large gulls, so it could be that they're getting better at foraging.

Now, one thing I like about ornithology is it has a lot of game theory, just like economics does. So sometimes when I read it, it feels very familiar. So let me ask you whether you all have the same problem that we do. With economic theories of signaling, once you get past the very simplest model, typically there are so many multiple equilibria that theories are hard to test. They can predict all kinds of things, and you don't know what to do next. Now does ornithology have the same problem with signaling, an extreme of multiple equilibria?

Yeah, well, I think so. The question is, is that a bug or is that a feature? Because nature really does look diverse, so the idea that there could be multiple equilibria is not a problem for us, or at least for me. And also, as you could tell from a lot of my answers, I'm really interested in history itself as a, as, you know, interesting explanatory powers. The other feature though is that most of my colleagues— many of my colleagues in evolutionary biology have bought the economic line that communication is about efficient exchange of information. But there's a lot of things we communicate about that isn't about information, right? And that's been— a lot of my work has been on ornament and sexual display, right? And the popular idea is that beauty and the sexual attraction in birds and in nature in general is a kind of efficient way to communicate actionable information about mate quality. But the other possibility is that it's merely beautiful and that's— that it is an irrationally exuberant market bubble in a genetic mating market, right? And that they're off the ranch. So I am really fascinated by those kinds of communication that are about suasion and not about information, right? And so there are some contexts where, of course, you know, that signaling theory applies well, but there are plenty of others where it doesn't.

Here's part of what bugs me. So as an economist, I see multiple equilibria. Whether I like them or not, I feel comfortable with it, right? So you've stressed in your work there's a certain arbitrariness to a lot of aesthetic values in birds and indeed elsewhere. But if you just look commonsensically at a lot of animals, including birds, including humans, it seems that markers of health and fitness and vigor are strongly correlated with sexual attraction. And that's not arbitrary. So we have these models with a lot of multiple equilibria. And then we have our common sense, which says go to the gym to get a date. In birds also. How does that all fit together? Doesn't that mean it's not arbitrary?

Well, you know, the interesting thing is that I think you have there, you have multiple ways to predict that outcome. One, for example, is that— well, let's— I'm going to take an aesthetic example., right? And for example, say you went to the symphony and there was a violin concerto, or if you prefer a blues concert or even a rap concert, right? And in the middle of the cadenza or the solo or the biggest thing, the performer begins to break out into sweat, right? They're really exerting themselves. And the question is this. Do we like the music because they're sweating, or do they have to sweat in order to make the musical performance that the audience likes? And both of those are equal, but most people would say that this is an indicator of quality because they're pushed to motor limits, but aesthetic processes are gonna do the same, right? We don't like the ballet because many amazing artists and athletes are injured in the process of producing the ballet. Because of the aesthetic impact of the ballet. And so there are other hypotheses for why traits are extreme and may be at the limits, performance limits or health limits of those individuals. So how do we differentiate between those two? Well, I spent a lot of time thinking about that, and I think that the special hypothesis, the one that demands specific evidence, is that the correlation is actually a result of the relation between the signal and some other kind of benefit other than the benefit of beauty.

But now I have cardinals and blue jays in my backyard. I enjoy them greatly. I like their colors. If bird aesthetics are arbitrary to the mating processes of birds, why do I also find it beautiful? Isn't that a funny coincidence?

That is deeply cool. I think that's because, you know, humans are intelligent and we have time on our hands and excess cognition and curiosity to burn, and that leads us to become fascinated by nature. But interspecific aesthetic regard is a fascinating thing. I mean, in the case of color, in the case of song, It's explicable in some ways because at least some of this is physics, right? We— there is an inherent wavelength relationship between various color combinations. The same for acoustics, right, which we can imagine the harmonic relations between notes in a birdsong just like we could analyze a piece of music. But the real fundamental mystery is why do flowers smell beautiful? And that one does not have, at least immediately, appealing answers because, yeah, it turns out there are no receptor genes in common between a bee and a human, and they're responding to the same flower odors in a similar way. I don't think it's because the olfactory space is just— you know, filled with all sorts of other things and that's where they're left and we learn about that. I think they are generally positive, so I think that's a— there are graduate-level research questions to be pursued in interspecies— interspecific aesthetic impression.

Building on that example, what can avian evolutionary theory learn from how flowers attract pollinators through signals. It seems they use color, they use nectar, they use deceptive mimicry, but it can't be the same kind of Fisherian co-evolution. Yet the final result is beautiful. So doesn't that imply it's not Fisherian co-evolution that is generating the beauty?

Well, certainly, one thing about pollinator and plant interactions is that they're different species, right? From the pollinator perspective, the pollinator's getting food. Nectar and sometimes eating the pollen. But from the plant perspective, the plant is getting animal aid in dispersing their gametes to reproduce with other plants, right? So what is the plant doing? The plant is investing in another animal. In order to do that, it has to advertise its opportunity, right? So this is really in the realm of advertising. And so what the flower really has to be is memorably rewarding, right? And so to me, that's like going into the grocery store and you look at a Coke can or a box of cereal, and there's literally nothing on the can or on the box that will tell you anything about what the experience of eating or interacting with that product will be like. And that's exactly what flowers are like, right? And so there's a whole realm of this field in biology trying to emphasize coevolution, that particular flowers and particular pollinators interact. And of course those do occur, but the vast majority of flowers are pollinated by generalists, and the vast majority of pollinators are generalist pollinators, right? So they have to be memorably rewarding. So some of them are like Doritos, you know, you reach over and you grab one, but it's not really what you need. And then some products you'll go further for, because they're really, really rewarding. But— and this implies actually that bees are making choices. And if bees were not making choices, then the world wouldn't be full of beautiful flowers, right? All the flowers would be exploiting that one button that was the most efficient way to get that bee just to show up and feed. But of course, all the flowers would come to look like each other, and then they wouldn't be carrying their pollen to another one of their same species. So the whole thing would fail.

Right?

So bees are making choices and they're making aesthetic choices based on the memorably rewarding experience of visiting a flower. Of course, for a bee, a flower is like architecture plus olfaction plus, you know, and actually electro— electric. It turns out hummingbirds and insects establish a static charge as they fly, and so as they approach the flower, it's like, you know, when you rub a balloon on your hair, you can feel the balloon getting near your hair, your hair starts to stand up or whatever. As they approach the flower, they can actually experience this electric charge. The hairs on their body stand up. And so they can tell, and of course, when the bee forages at the flower, the charge is neutralized, right? So they can tell whether the flower, how recently that flower has been visited before they even get there by the static force acting on their hairs. This is a subjective experience that really influences their choices in the world. So what does that have to do with bird breeding, your question? Well, it has to do with the fact that we put the subjective experience of the animal at the center of our analysis. And indeed, that leads, I think, to really accurate understanding of what's going on in nature. You mentioned Fisher. We didn't talk about that, but what is a Fisherian process? A Fisherian process is a self-organizing sexual selection mechanism where genes for preference, liking long or short tails, become correlated with genes for the trait, having a short tail or having a long tail, right? Individuals who like long tails are going to find mates with them, and anyone who likes short tails are going to find mates with those. So those two forms of variation will start to covary, and that means when you select— when an individual selects on a mate, they're also indirectly selecting on covarying or correlated genetic variation for preference. So that means the whole thing can just run itself, and of course it does and produces a lot of diversity.

Before we move on, let me put in a plug for your excellent and award-winning book, The Evolution of Beauty. Now let's go to birding. Let's say you're a birder with a collecting mentality. Should it count if you only hear the bird, like a nightingale in a thicket?

Well, you know, it definitely counts. The question is, what does it count for? Right? And I am one of those birders, you know, and moving from animal subjectivity to birder subjectivity, right? Birdwatching is— I mean, what the list really is about is accounting for your subjective experience of the bird, right? It doesn't just matter that there's that bird in that tree. What matters is, did you see it or did you hear it? Right? And that's your experience of it. And hearing a bird, for some birds, is more spectacular than seeing them, obviously. But yes, but people do. Make different sorts of lists. And typically, for what's called one's life list, people really want to see the bird. You know, have I ever seen the bird? And then, but if it's for a more minor list, your day list, your state list, or actually data points, then hearing it is just as good as seeing it if it's for the purposes of data, right?

Now, amateurs have so much ready access to technology— iPhones, AirPods, so much more. How is this shaping the evolution of birdwatching?

Oh my gosh, it's— it revolutionized it. There are two programs produced by the Lab of Ornithology at Cornell University that have really transformed birding. One is called eBird, right, where you can keep live checklists on your phone as you go. That's— and then the other is Merlin, which will actually identify photographs using artificial intelligence of birds. So they take a photograph of a bird and load it up and it'll tell you what it is with, for most parts of the world, with incredible accuracy for common birds and really quite elaborate ability for even obscure birds. What you have to say now is in addition to an electronic camera, young folks today are birding with their phones. Their data are going up to the cloud in real time and influencing what other birdwatchers are doing and becoming the subject of science through sort of citizen science. So it's really been a huge revolution.

So birding in this sense is a bit like chess, a quite unlikely winner from the rise of the internet and technology, but exploding in popularity?

I don't know. I mean, I guess my fingers aren't quite enough on the pulse. I, you know, we went through a long time because as a kid, I grew up birding. I started at the age of 10 and for me it was all about going outside. It was like, you know, "I'm going out after school." The screen door slams and there you go, you're off outside. And I, you know, have been concerned for a long time about whether the way children are raised and the in the modern world that not enough of that is happening. If people get back outside through their phones, I think that's great. But it does— it is still— I'm old school. I'm not keeping my checklist during the day as we go. Of course, that means my data aren't probably as high quality either. But I think some people are.

What's the most important bird missing from your personal checklist? And hearing it doesn't count. You've already told us.

You know, well, there's lots of different measures, but sometimes it's all, there's no rationality to it, right? I once took a trip up to, oh, about 5, 6 years ago, I took a trip up to northern Norway to see Steller's eider, a duck that, that if you imagine between Norway and Alaska, what is there way, way up there? That's where they nest, and in the winter they only barely come down to Norway or Alaska. And so I wanted to see them, and I got up there, and a date of 10 years ago, I would've seen, on that date, I would've seen 1,000. 5 years before, I would've seen 100, and by the time I got there, climate change was happening so rapidly in the Arctic that I got there, and there were none to be seen on that date, right? And so I've been really desperate to see Steller's Eider just 'cause, right? It's 'cause you take a notion, and that's the beautiful thing. I would love, what I'd really love would be like what's, you know, 'cause the history of life is a tree. I've been very interested in the phylogeny of birds, you know, who's related to whom, the big tree of life and the tree of birds. And you can say, well, I've seen these and these species, but I haven't seen these yet. What's the species most unrelated to any species I've seen that I could— What would be the species that would give me the most, the best addition to my total sample of avian diversity?

A moa.

Well, I mean, well, yeah, exactly. Well, you know, the answer right off the bat for most people would probably be the hoatzin. And the hoatzin is a very weird vegetarian or leaf-eating Amazonian bird. And the bird probably most unrelated to any other living bird. After that, it gets a lot of specific things to, you know, what you've seen. But yeah, the next trip you're planning, those are the most important birds to see.

It seems there's been a lot of big advances on the research side lately. So there's cheap tagging, much easier, radio telemetry, applying machine learning to birdsong. What's the most important thing going to come out of all these very new advances?

Well, you've only just begun to skim the surface. I mean, I used to think, and I'll say this proudly just to embarrass myself, I used to think that the chicken genome was the most uninteresting thing I could ever imagine, right? And it turns out, you know, genomics has really been fantastically revealing for features we ultimately want to know about, like, you know, the funny features that characterize birds. So transcriptomes, taking a tissue and sequencing all of the RNA that's being expressed at the moment, getting an idea of what expression states are in different kinds of cells, on up. On your tagging technology, that's been fantastic. The Max Planck Institute for Animal Movement in Germany has put up ICARUS, a big satellite that is capturing in real time data on animal movement, individual animals. So they're getting basically the whole entire movement of a life of a wild animal. And you get enough of those, and sure enough, you get a very new view of what's going on in the world. You know, the interesting thing about progress is you never know what it's going to turn up, right? I mean, and that's where the opportunities are. But, you know, figure out what's the best way to use that technology to answer or address a cool issue. In birds.

What's your favorite word for a group of birds? Is it a covey of quails, an unkindness of ravens, a parliament of owls? Which one?

Oh, I don't know. I think my favorite, my favorite word for a group of birds would be the genus. That's a different group, a historical group.

Should we use bird feeders in our backyards?

I think so. I love my bird feeders and and I really enjoy them. And I think that there are some downsides, you know, in particular, being sites of potential infection for diseases that are moving through. They're the opposite of social distancing, right? They're social concentrating. So they can't be centers for conjunctivitis-like illnesses in finches recently in the United States, etc.

Do they just worsen the Malthusian equilibrium? And how well does the Malthusian subsistence theory predict bird populations? Like, are birds at the margin of subsistence as a whole?

Well, you know, one of the things that Malthus did take into account was like, you know, or much account into was, you know, variability, right? The fact that, you know, an ice storm, for example, birds, a lot of birds in the winter, if you think about birds at your feeder, they can do fine at -5, -10 degrees Fahrenheit, -20, you know, if you get chickadees, right? If they have enough food, but if they don't have access to food, they will die in a single night, right? And so these ice storms, which could be, you know, just 32 degrees covering all the food, the whole environment with ice, for a day can be just devastating for lots of birds. If there weren't feeders, their population would really harm. Things like Carolina wren, which is a bird kind of expanding, and I think a big ice storm will set down Carolina wren populations at the edge of the range in New England or the Mid-Atlantic for, you know, 5 years it'll take them to rebound after that.

Do we have good theories of bird property rights? Somehow invoking the ideas of relative scarcities to explain when birds are territorial, are not territorial, or is that just a big mess that we don't understand?

No, there are some, I think, good things. So if you're, say, an aerial insectivore, you're catching insects in the air, you'll be territorial if you catch insects that are 15 inches away from a branch, right? Just, wheep, going out for a little Sally. You can defend all those branches, that's my territory. But if you're a a swift or a swallow and you're flying hundreds of meters or hundreds of feet up in the air and all of it, you know, it's very hard to defend that, right? So you give it up, right? You know, lots of marsh birds, marshes are very rich, lots of bugs. So if you can grab your patch of lily pads or bulrushes or cattails, you can really do well. You want to defend that. But, you know, if you're a puddle duck, there's going to be lots of water in there. The thing's, you know, somewhere, you know, 18 inches below the surface of the water. You can't really defend that and so for the most part, you know, it sort of varies with your body, your ecology, et cetera. You know, and we can do experiments. So for example, sometimes hummingbirds will defend a floral resource and then when it gets big enough, they'll just give it up because there's no reason to do it anymore.

Now, in all of these conversations, we have a segment in the middle called Underrated vs. Overrated. I toss out a name, an idea, a place. You tell me if you think it's underrated or overrated. Got it?

Okay. I'm not sure we have this. We will. It could be a combination of Rorschach test too, because what do we think of the thing that's named? But yeah, go for it. We'll go for it.

Roger McGuinn.

I don't know who that is.

I thought you were an expert about the birds. Here's an easier one. Larry Bird.

Larry Bird. Larry Bird is perfectly rated.

The birdsong music of Messiaen, the French composer.

Oh, well, you know, I think way underrated. I love that stuff.

Charlie Parker. And what's your favorite cut by him?

Well, I know it when I hear it, but I don't— you know, I actually have albums where I know which Cut His Witch, but I don't know, actually I haven't looked at the liner notes enough to know.

It has to be ornithology, right?

Yeah, yes, well, yeah, but yeah.

The Alfred Hitchcock—

Underrated.

The Alfred Hitchcock movie The Birds. Overrated. Why?

You know, I mean, I think it does a lot of damage to be afraid of nature, right? And, you know, and I think— I know people that are bird-phobic and I'm not sure whether, you know, whether arises from that, from something like that movie. So yeah.

Is the diversity of the protagonists in The Birds a kind of portent? Does that make it more terrifying?

Or just the sinister turn that all of nature is out to get us, you know? I mean, I think when I saw it, you know, and maybe it is black and white, I saw it on TV in black and white as a kid. I just crossed my arms and, ah, I don't I've never seen it since.

John James Audubon as an artist, overrated or underrated?

I think we're still underrating what he achieved.

Who is your favorite bird artist? Is it him?

An artist?

No.

George Meash Sutton, George Sutton, who is an American watercolorist of American birds. Fantastic, fantastic. Renditions of birds. He really was amazing at both the art and the ornithology.

Putting aside birds, travel in Suriname. Should I go?

Well, I haven't been in more than a decade, but you should definitely go. It's a marvelous part of the world. I think it's on hard times in recent decades, Beautiful, beautiful people and marvelous avifauna.

Let's say a good friend comes to you who has reasonable income, well-educated, but not an ornithologist, not even a birder, but interested. And this person says, "I have a month of my life and I want to go around the world. I can go anywhere feasible and look at birds." What is the perfect tour for that person? You're in charge. Where do you send them?

That's fascinating. You know, I think one of the things that can impress a person without the experience to understand that the hard work is worthwhile or will be worthwhile is spectacle, right? And so things like, you know, penguin colonies in the Antarctic are just profoundly amazing. And so that would definitely be a possibility. Other kinds of ornithological spectacle, depends how young they were. Some people, you know—

Let's say they're 40, so they're able-bodied.

Yeah, yeah.

But they're not a rock climber. Do you send them to Colombia, to Panama?

Oh, yeah, but the problem with some of those places is, of course, is that the bird watching is hard. It really is hard work. Work, right? And I know I've taken students who know little— well, they've had half of my ornithology course, taken them to Ecuador. And, you know, we've seen 100, you know, 490 species of birds in 10 days. And usually their brains are fried, right? And we just, you know, it's a lot of work. And So, but I think you need to be over a little hump before you do that. So spectacle would be good. So another thing, one thing I did that was last, in 2018 in Brazil, I went to see a nesting site, a nesting colony of Spix's macaw. This is a very, Oh, sorry, Lear's macaw. Fix's macaw is the one that's near extinct. Lear's macaw, it's a sort of aqua green— aqua bluish green turquoise parrot, and it nests in a cliff face where there are holes, and they come out of this cliff face in the dawn. It's kind of a huge cliff with a kind of cavern in front of you, and they fly around, and it's just unbelievably moving.. It was unbelievably beautiful and these are intelligent birds that live for decades, know each other as individuals and unfortunately critically endangered but being well conserved at this site. So there are a number of things like that. An oilbird cave is an incredible thing for the right person. These are nocturnal frugivores. They live in caves in South America in the Andes and they fly out of the cave at night and fly dozens or even hundreds of miles out to forage on avocado and palm fruits that they bring back to the cave and feed to their babies. And they're called oil birds because they used to capture them and render them down for oil and cook with it and, you know, make candles out of it. That's how fatty they are, you know, from the avocado oil. But going to an oil bird cave is amazing, and often you have deep in the cave, you'll see a forest of ideolated seedlings, all white. No photosynthesis. They've started to propagate in the guano, and the guano will look like guacamole green because that's what they're actually eating, avocados. It's sort of the edges of ornithological experience. So for the right person, some things like that could really be the best.

Why is it that birds such as falcons and cormorants hunt and fish with us. How did that happen?

You know, domestication is a cool thing. It's like, well, people intercede with nature and somehow co-opt the—

But somehow. I want to know the somehow. Is it that they're smart enough to figure out gains from trade? Has it become instinct?

I think it's that mostly that, well, You get the animal while it's young. So traditionally falconry, you would get the bird on southern migration and capture it. You could tell it was naive. You could fool it easier, so it's easier to capture. And then you'd either hold it for a year over the winter and then let it go, and then later you kept with it. You know, they haven't become a domesticated strain, if you will, like a chicken or a dog. But you're co-opting the capacity. It's like having a pet parrot, right? The parrot thinks it's a human and the way it develops in this new environment with human social partners is extraordinary and different. And so that's how that works. The fishing in the cormorants, I don't know if it's still going on. It was a tradition in areas of Japan, I know, but I've never witnessed it or seen it happen. That those birds are captured from the wild. They don't breed them, I don't believe.

Here's a question from a reader, and I quote: Osprey. They hatch early July, are flying by the last week of August. The adults leave around September 15th heading south, and the young ones hang around for a couple of weeks bulking up on the late landlocked salmon spawns, then head south. End quote. How exactly do they know where to go? How exactly does this bird instinct work?

This is great. And this is actually an area where we're learning a lot because of new technology. So now we have these GPS transmitters that you can get satellite information in real time on where those birds are. And this is the work, mostly I believe, of Rob Bierregaard, who has done this in ospreys. And most ospreys spend the winter in a very narrow area area of the llanos of Venezuela and Colombia. That's where the ospreys go, or at least in this continent. And so what the young ospreys do is they fly off the East Coast, kind of wandering around in the ocean. Sometimes they hit Bermuda. Sometimes they, you know, wander. They might return to North— South Carolina. And then they basically mess it up. But somehow or other, eventually they get down to the Antilles., and they realize, oh, and they follow the chain of the Lesser Antilles down to South America. And then on the way north, they realize, oh, we've got the Guajira Peninsula in northern Colombia, and then we pass over, oh, we get to Jamaica, and then they go boop, and they return up through Florida to these. And then what do they do next year? They go down to Florida, jump over to Cuba, come down the islands. So it's a combination. So what do birds need to migrate? They need to have a a magnetic compass, they also have a sun compass, they have to have a clock and an experience of the sun. And they have to know kind of— they need a map about which we don't know much. And then they have to have a bearing, like where they're going, and then a sense of how far to go or from a map whether they've reached their destination. And then once they— in real life, They experience the world and then refine that with experience. So they have some innate properties or capacities and then a lot of experience. And of course a lot of them fail to learn and I'm sure some of those birds that wander out in the ocean fail.

How much is there a generalized G-factor for the intelligence of birds? So for instance, if they're good at using tools—

A what factor, pardon?

For humans, we would call it a G-factor. So if you're smart at one thing, you tend to be smart at another. How much, if a bird is, say, good at using tools or good at playing, is the bird just smart flat out? Or are birds highly specialized in their smartness? They're really smart at one thing and then very stupid at another.

Yeah, that's a great question. I think that There are lots of examples of extraordinarily specific smartness in birds that doesn't apply. But the birds that are really smart tend to be smart at a lot of stuff. So there's a few of them that stand out with breadth of smarts, and I'm thinking parrots and crows, corvids and parrots. They're the most notable. They stand out above everybody else. And indeed, you know, now if you look at the paleoneurons, which are basically the ones with the smart connections, A parrot will have more paleoneurons than a monkey with a brain that's 4 or 5 times as large, right? So they really are— they've gone a different route in their organization of cognitive complexity, and they're really doing it really efficiently. But there are all sorts of extraordinary intelligences that are very, very specific in birds, I think. That don't have that property.

Do you think ravens and crows understand death?

Wow, I don't know.

I have, you know, a lot of birds go crazy when they see other dead birds, right? They make a lot of noise. Doesn't mean they understand death, but they know something's gone wrong.

No, no, no, but I do think there are examples of birds— Carl Safina has catalogued these, and I don't know that literature, but there are certainly examples of birds that appear to be mourning or understanding that their compatriots are physically present but no longer living, right? Whatever that is. I wouldn't be surprised if they do, right? I mean, they know each other as individuals. Deeply and appreciate it. And you know, you were mentioning albatross earlier. One of the things about albatross, the big ones, they nest every other year. So at every albatross colony, there's an even year cohort and an odd year cohort that returns. And they take off the other year, then come back to reproduce. And they are monogamous over decades if they live long enough, right? And so they'll spend that year off, 9 and a half months or 12, 15 months, whatever it is, and they'll even fly around the entire southern continent around Antarctica a couple times, then return to the Farallon or Malvinas Islands and then meet that same mate and then mate again, right? And they recognize each other. And so those kinds of, I certainly think they would understand that that bird is not returning.

And birds have culture, right?

Absolutely. About half the birds of the world, just for one example of culture, half the birds of the world learn their songs from other members of their species, almost always not their parents. And what that means is you got a decoupling from genetic variation and the phenotype or the presentation of the animal. So what do they do? They learn from other individuals and they learn preferences. So the birds in the areas around Chicago, New York, and Boston sound differently, just like the people do. And for pretty much the exact same reason, right? And it's not because of the wind in Chicago or the baked beans in Boston, right? It's isolation by distance and historical contingency and cultural change. So birds have been doing culture for tens of millions of years, which puts us to shame certainly in terms of diversity. Of course, we piled a lot of culture on our one little invention and that's— notable and interesting in its own right too.

Will puffins perish?

Wow, you know, the oceans are getting deeply screwed up and climate change, both of these combinations are really affecting the Arctic or northern— I don't think the puffins will go extinct on, you know, a couple century scale but their distributions and lives are really gonna change, I think.

Should we try to find the DNA of passenger pigeons and bring them back?

You know, I find this rewilding business to be, or revivification, to be really off-putting. However, and mostly because— But why? Well, mostly because, I mean, the reason why it went extinct extinct is that it needed continental scale richness of chestnut and oak forests in order to survive and there's just no place in the world where that is, right? They're extraordinarily social. They only laid one egg, right, a year, which means that they were very— they were what we call K-selected. And so as a result, there's very almost no place for them in the world. Having said that, most of my criticism are also framed by the unrealism of the technology. Just like, okay, so we find a few genes and we put them into a band-tailed pigeon, the sister group, the closest extant species, and we put them in and we kind of make it a little bit more like a passenger pigeon. Wouldn't that be cool? It's like, well, no, that's not really cool. But it— I mean, if we really had the technology to really bring back passenger pigeons, sure, I'd be into that. But we're very, very far from that.

What's the best overall framework for thinking about the actual value of avian biodiversity when we face real trade-offs? Say, are we gonna put in more wind power, right? So it's gonna kill some birds, but it might help with climate change. How do we even begin to approach a question like that?

Yeah, yeah.

Do we ask the economists? You're not gonna ask me, right?

You know, I had, actually, I had a, I'm just grading term papers right now in ornithology, and I had a term paper in ornithology exactly on this question. Pretty good, you know, by a political science student with interest in environmental policy. So yeah, I'm not sure. I don't know if I've got the training to say that except to understand that, yeah, it is real trade-offs. I think we're making them all the time. I think in general, I mean, if there were enlightened policy like, you know, carbon tax, etc., even a little bit of it, you know, we'd be in a much better situation to see where, you know, maybe it would solve itself. But, you know, there's certainly a lot of reason for concern. There's also a lot of interesting resilience, right? We're looking in New England here where I live. You know, we used to have chestnut trees and they disappeared and we used to have elm trees and they basically became irrelevant. And now we're looking at hemlocks disappearing because of the woolly adelgid and now ashes, the emerald ash borer from China has arrived and so we're losing major trees and yet there still seem to have forests. We still have a lot of some birds in them. Now less birds, fewer birds, that's true but there seem to be not as much— some kind of resilience despite this change but I don't know. I wish I had a better answer. I'm still a historian rather than a predictor in my work.

Is 1 billion too many sparrows? No. Is it wrong to own a cat that you let outside? Yes. Just flat out wrong?

Yeah.

But if we don't know how to make the trade-offs, how do we know it's wrong?

Well, because I mean, that is really, really clear. I mean, you have concocted, created an artificial predator that you're keeping really happy and healthy and feeding it and keeping it in peak condition so that you can have it go outside and entertain itself, and its entertainment is damaging the world. I mean, you know, the scale of cat death— I don't know the numbers, but way more birds are killed by cats than are killed by all the wind power in America. It's devastating. It's billions of birds.

I read an estimate recently, did not seem to be scientifically serious, but it suggested that a billion birds die each year just by crashing into human things. Is that plausible, that the number's that high?

Sure, but I'll tell you that the data for cats is way bigger than that. So cats, you know, kill more birds than all the skyscrapers and windmills And these are, you know, pets and also feral cats that are maintained by humans.

Very last segment of our chat. It's what I call the Richard Prem Production Function. How did growing up in rural Vermont help influence who you are professionally and lead to your success?

You know, a lot of my science is deeply rooted in natural history, right? I am I'm not interested in law-like properties of nature, but in the idiosyncratic instances. And a lot of that, that view grew out of birdwatching, grew out of my childhood and being interested in birds. And a lot of people do birding and then go into science, right? But for me, somehow that birding experience affected how I do science. And I think that somehow there, you know, I have kind of a minority style of mind in modern science. A lot of great scientists out there, but most of them are not thinking the way I do. And so as a result, there just seem to be more opportunities.

What's that difference in how you think? How would you characterize it?— in its most fundamental form.

I really care about birds. I think that birds are really interesting. So I am not necessarily worried about what the other guy— I mean, here's the deal. My favorite Onion article was the title, "NSF study shows science is hard." Yeah, science is hard. So what are people's response to that, the fact that science is hard? A lot of people will go and say, "Well, if I'm going to expend a lot of energy, I better do something that somebody else thinks is important. So what do you think is important? And they look to the sides and they think that that is doing something that somebody else thinks is important is their mission, right? And I think about the birds and I think, what is the coolest thing that I could do with my time now or this day, this next day ahead of me? That would solve some answer. And of course, I love to connect that to big science, whether it's like, where do feathers come from? Or how do bluebirds get blue? Areas that I've worked on. And in many cases, they turn out to have deep implications for other field. But it's that regard for the birds. It's a kind of what Donna Haraway calls situational related knowledge, right? That you— it's not the voice from nowhere, it's the specific instance, the view from here, and where that here is. So, and I think, you know, I recently read a paper in an esteemed journal called the American Naturalist, right, which is very highly ranked but has this sort of, you know, sounds like a wildflower garden club report or something. Anyway, the American Naturalist, and it was, you got 2,000 words into the paper before you realize that it's about housewrens in Ohio, right? Now, you know, what is going on there? I think people are embarrassed about the position of their work. They're so interested in the general principles of like, "Oh, this is a big incisive issue that biologists need to solve," and that generalized frame is leading us that's often astray, to do work that's uninspired or a lot incremental like everybody else is doing, or et cetera. So, and maybe that, you know, you're pushing me in new ways. So maybe it's being the only birdwatcher that I knew under the age of 25 as a child for a long time led me to think, you know, you just gotta rely on yourself. To figure out what's of value in your work.

Who first spotted your talent for studying birds? Other than you.

You know, as a kid, I interacted with a number of people that were mostly garden club ladies, right? They were my mom's age or older, retired people. They had cars. I did not have a car in 4th grade, 5th grade, right? So it was a great deal. And they certainly did a great deal to cultivate me.

So garden club ladies are underrated is what you're telling us.

Oh, absolutely. That's a big one. And then natural history, their introduction to flowers and ferns and to another way of being outdoors, which was actually I related to much better than the Boy Scouts, right? Which I left pretty quickly. But then I met a young Yale-y, then hippie, hanging out in Southern Vermont, a guy named Tom Will, who's now just recently retired from the Fish and Wildlife Service. And he was a great mentor early on in birding.

Last question. Other than the obvious, such as intelligence, hard work, how do you recognize a very talented prospective ornithologist? What is it you look for?

It's like, you know, you just get these responses. And of course, it happens— luckily, I have had— well, I've had the privilege to teach lots of really amazing people. But you're explaining something to somebody, giving them a bit of a context, and then all of a sudden, you get a shot back. You get a response back. And you're like, oh, yeah, they got that. This is the next thing, right? They got that. Oh, and then you get— and it pitches back, right? That interplay where you lay something out and they see where you're headed and ask you a question. And they often will say, wow, "Hey, I don't know if this is a dumb question, but what about blind?" It's like, "That's not a dumb question. That's the fundamental focus of where this whole field is going." And I've experienced— I used to teach at the University of Kansas, and in Kansas, it was a big, very huge university, but the great students were as good as anywhere. And then you would have a marvelous experience of of discovering a student who was really smart and didn't actually know it. They might have been the smartest kid in their town, coming off somewhere in West Kansas, but they had never had an opportunity to experience what they were capable of, right? So it's really that response. Are they coming back at you with their own thoughts?

Richard Prom, thank you very much. And again, a big plug for Richard's book. The Evolution of Beauty: How Darwin's Forgotten Theory of Mate Choice Shapes the Animal World and Us. Thank you, Richard.

Thank you. That was really fun.