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Okay, but did birds originate the open relationship? · Okay, But... Birds

• 0:00
  We pledge allegiance to each other and we will be faithful and love each other forevermore.
• 0:06
  It's complete bunk.
• 0:30
  Okay.
• 0:32
  There are two ways to tell a bird love story.
• 0:35
  There's the March of the Penguins version, two birds waddling towards each other across the ice, swolling music, a voiceover about devotion and mating for life.
• 0:44
  And then there's the Maury version.
• 0:45
  The DNA results are in You Are Not the Father.
• 0:49
  Last week, we put out our 25th episode, which feels like a good excuse to go back to where this whole thing started, episode one.
• 0:55
  Okay, but is bird monogamy just PR?
• 0:58
  That's where we drew a line between two kinds of monogamy.
• 1:00
  Okay.
• 1:01
  Social monogamy is who you see a bird with, the partner it shares a territory with, builds a nest with, and raises chicks with.
• 1:08
  Genetic monogamy is who actually made those chicks.
• 1:11
  And here's the thing.
• 1:12
  Although most birds are socially monogamous, almost none are genetically monogamous.
• 1:16
  The gap is where the drama lives.
• 1:19
  So 24 episodes later, here's today's question.
• 1:22
  Okay, but did birds originate the open relationship?
• 1:25
  And to jump ahead, the answer is not quite.
• 1:28
  Not because birds are more faithful than we thought, but because open relationship is our term, built around our rules for getting around our expectations.
• 1:35
  Birds never agreed to any of that.
• 1:37
  They aren't bending the rules of monogamy.
• 1:39
  They're running on a completely different set of pressures we keep trying to read our own story into.
• 1:43
  Food, neighbors, predators, timing, genetic compatibility.
• 1:48
  But semantics aside, I'm excited to welcome Dr. Wenfei Tong, biologist and author of the book, Bird Love, to the show.
• 1:54
  After the break, Wenfei walks us through what bird partnerships actually look like when we stop projecting.
• 1:58
  We get into why cooperation and conflict are happening in the same nest at the same time.
• 2:02
  And we talk about what all of this says about the stories we tell ourselves.
• 2:06
  Stay tuned.
• 2:12
  Well, welcome back to the podcast, everyone.
• 2:14
  I'm really excited to have Wenfei with us today.
• 2:16
  Thanks for joining us, Wenfei.
• 2:17
  Thanks so much for having me, Scott.
• 2:19
  Yeah, of course.
• 2:20
  So in episode one of the podcast, we proved mating for life is mostly PR, but monogamy is just one of many ways that birds pair up and raise chicks.
• 2:28
  Could you walk us through the range of bird mating systems?
• 2:31
  Yeah, thanks, Scott.
• 2:32
  That's such a fun topic.
• 2:34
  I think one of the things I really wanted to cover in this book, Bird Love, was just the idea of that word you mentioned, range, that there's such a range and such a spectrum and just such flexibility.
• 2:48
  not just among species, but within species.
• 2:52
  So, you know, humans, we like to classify things.
• 2:54
  We like things in neat, tidy boxes.
• 2:57
  So we've got four main categories of mating systems.
• 3:00
  You've got social monogamy, and then you've also got polygyny.
• 3:05
  So one male, multiple females.
• 3:08
  You've got the flip of that, polyandry.
• 3:11
  So multiple males mating with a single female.
• 3:16
  And my favorite, polygynandry, which humans sometimes refer to as promiscuity.
• 3:21
  I think it's about the same thing.
• 3:22
  It's just everyone mating with everyone else.
• 3:24
  Yeah.
• 3:25
  No strict pair bonds formed.
• 3:29
  And some of this can take place flexibly within a single species.
• 3:33
  And we can cover that later.
• 3:36
  You know, the whole mating system thing is really about investing your genes in the next generation.
• 3:41
  Who wins the lottery in terms of getting more genes?
• 3:44
  If you think about finding a partner as a way to get more bang for your genetic bark, then sometimes if offspring are really expensive to rear, like a human or like a lasian albatross or a long-lived bird that needs a lot of learning and experience and knowledge,
• 4:08
  childcare, then often it's not possible for both parents to raise the chick.
• 4:14
  So I think for the majority of birds, social monogamy exists because you basically need more than one parent to successfully rear anyone.
• 4:24
  And there's so much cruel conflict that goes on in terms of who gets to do more of the care, who has to do more of the care and how you could punish your partner with.
• 4:34
  if they try to, you know, play hooky or mate with someone else.
• 4:40
  So for birds that don't need so much childcare, where it's possible for one parent to successfully raise the offspring, I think that's where you tend to see the polygyny or the polyandry take place.
• 4:53
  Yeah, yeah, or the promiscuity.
• 4:55
  But it makes sense that like, in general, it's it takes a lot of work to raise chicks, especially, you know, I think about the chickadees that we study.
• 5:02
  And if you have 10 little baby chickadees in a nest box, it's impossible for one parent to bring enough food over the period of time that these chicks are growing rapidly to raise them.
• 5:13
  And so obviously, evolution would then favor, yeah, at least two people.
• 5:17
  or two birds raising these chicks.
• 5:20
  And in some cases, you even have helpers at the nest, which we've talked about in other episodes.
• 5:24
  But yeah, I think it makes intuitive sense that this social monogamy piece would be so common.
• 5:29
  And then it's really fun to think about like, all right, yeah, when you don't have to invest so much energy or one individual can successfully raise the chicks, what does evolution do with those mating systems is really cool to think about.
• 5:41
  And some of my favorite examples are populations where it could go either way.
• 5:46
  So a lot of shorebirds, especially, they have fairly independent kids, right, who hatch with their eyes open and they can run fast and they can find their own food.
• 5:55
  So really, they don't need that much care.
• 5:58
  And then whoever can skip off first...
• 6:01
  often does.
• 6:03
  And sometimes I think there's a study looking at lots of shorebirds.
• 6:07
  And in general, if the migration is very long, the female tends to disappear first and leave the male holding the chicks.
• 6:18
  I guess the explanation there is partly it's so expensive to lay the egg.
• 6:23
  She's not...
• 6:24
  She then has to fuel up for her migration.
• 6:26
  She's not going to also take care of the chicks.
• 6:31
  And then in some cases, it's a mating market game.
• 6:34
  It's sort of a game theory thing of whoever's are rarer, if it's males that are rarer, they're more in demand in a sense.
• 6:42
  So it's easier for them to find a new partner, in which case they get to abscond first.
• 6:46
  And vice versa, in a population of Kentish plovers, I think is the best example of this.
• 6:52
  If females are the ones that are very rare in a population, then they're the ones who leave first and the males are all holding the chicks.
• 7:00
  Yeah, the flexible examples are really cool.
• 7:02
  I saw a spotted sand viper nest once.
• 7:04
  Oh, yeah.
• 7:05
  They're cool because they're polyandrous.
• 7:07
  Yeah, they have sequential polyandry, right?
• 7:09
  So they like, the female builds a nest, lays eggs, and then once the male's incubating, she leaves to go do it again somewhere else.
• 7:16
  I think so.
• 7:16
  And she's bigger and showier and the males choose her based on her spot size.
• 7:22
  And yeah, very cool.
• 7:24
  Yeah.
• 7:24
  Yeah, and that kind of bleeds into the next thing I wanted to chat about, which is just like in Chicanas, for example, males do all of the parental care and females are territorial in these marshes that Chicanas live in.
• 7:37
  Phalaropes have females that compete for mates and the female phalaropes are brightly colored.
• 7:41
  And we tend to refer to this as flipped sex roles since it's most common that males are the colorful territorial ones.
• 7:48
  And what are your thoughts on how this evolves and what determines which sex invests more in the offspring?
• 7:53
  I mean, it seems like it's common in these shorebird-esque creatures.
• 7:57
  Yeah.
• 7:58
  And, you know, of course, we've come to this with a very mammalian and a very high investment by mother primate, great ape mammalian view of things.
• 8:10
  So I'm sure if you were talking to fish, the flip sex roles would be completely different.
• 8:17
  And actually, my son has a really lovely Eric Kull book about seahorses and pipefish and fish.
• 8:27
  paternal care being the predominant role in fish, in many fish.
• 8:32
  So yeah, I'm all for that.
• 8:34
  I think one of the things, one of the explanations everyone comes up with is just ancestry.
• 8:39
  So a lot of the ratites, the tinamoos, birds that seem to have split off from the tree of life of birds fairly early on, have predominantly male incubation and a lot of male care.
• 8:54
  And I think cassowaries take this to an extreme where the females are much larger than the males and fight for the males.
• 9:01
  And there's also that idea of if you only need one adult to take care of the kids, then it frees up the other one to start competing for them.
• 9:10
  So I think the only example of this kind of
• 9:15
  females being large and competitive and males doing all the childcare that exists in bird with altricial young.
• 9:21
  So what I mean by altricial young is very helpless, naked, blind, pink little chicks, right?
• 9:28
  Is black kukuls.
• 9:29
  And they're fascinating.
• 9:33
  They're part of the cuckoo family, but they're non-parasitic.
• 9:37
  Okay.
• 9:37
  And they're the only birds we know of with that kind of very helpless chick, where there's very strong selection, sexual selection on the females.
• 9:46
  The females, I think, 70% larger than males or something like that.
• 9:50
  Wow, that's...
• 9:51
  It's very different.
• 9:52
  And they do all the classic male things, like they sing...
• 9:56
  And they defend the territory and the males do all the childcare.
• 10:00
  So how that evolved in black kukuls is really fascinating, partly because the other kukuls don't quite do this.
• 10:09
  They may have some hints of sexual selection on the females, but they don't have such a strong skew.
• 10:16
  Yeah.
• 10:16
  Yeah.
• 10:16
  I didn't know that about black kukuls or that they were, yeah, this altricial versus precocial young.
• 10:21
  So when you were describing like the shorebird young, that's what we think about as precocial.
• 10:25
  Or if you've ever hatched eggs and had chickens, like when they come out, they look like a little bird.
• 10:30
  They're functional.
• 10:31
  They can run around, eat food.
• 10:32
  That's what we call precocial.
• 10:34
  And you know, when you're a kid who asks a lot of questions, you might be called precocial.
• 10:39
  But altricial is maybe what we're more familiar with, which all passerines have altricial young, where their helpless little pink don't even have their eyes open when they hatch kind of thing.
• 10:50
  So it's very cool that kukuls actually have altricial young, but this male parental care.
• 10:55
  And it could be, I think in some cases, that's...
• 11:00
  associated with very high predation, polyandry, or this kind of system.
• 11:06
  So black kukuls do suffer very high predation rates.
• 11:11
  I think spotted sandpipers that we were talking about often do too.
• 11:15
  Probably.
• 11:15
  So I guess in those situations, the explanation, I mean, all these explanations like not mutually exclusive.
• 11:22
  Yeah, exactly.
• 11:23
  Important to remember.
• 11:24
  It's helpful.
• 11:25
  And sometimes it's hard to test them is the other thing, but they sound good.
• 11:30
  I know you've got a series on cooperative breeding, an episode on cooperative breeding.
• 11:34
  Yeah, with Nancy.
• 11:35
  But I find it so interesting that the flip side of this is something biologists like to call cooperative breeding.
• 11:43
  Polyandry, that's right, cooperative polyandry, which basically means you've got a system where there's multiple males helping to feed the offspring of at least one female, sometimes multiple females as well.
• 11:57
  Hmm.
• 11:58
  So then the distinction between that and cooperative breeding in general sort of breaks down for me.
• 12:03
  Yeah, yeah.
• 12:04
  The idea, the thing a lot of those systems have in common is very limited resources, like a limited number of nest holes.
• 12:12
  And I think one of my favorite examples is eclectus parrots.
• 12:18
  you've got some flipped sex role stuff going on.
• 12:23
  So female eclectus parrots are this amazing bright red and purplish blue colour.
• 12:30
  And they live in places like Australia, Papua New Guinea, places like that.
• 12:34
  And the males are very blended in with the canopy green.
• 12:40
  still beautiful and striking, but definitely not the one you would typically pick as the male if you saw a photo of both sexes.
• 12:48
  Right, yeah.
• 12:49
  And there the nest holes are really in short supply.
• 12:53
  Ah, okay.
• 12:54
  And so I guess that's one of the explanations for why females will savagely guard their territories, their nest holes, and all the males are just dying to find...
• 13:07
  Any nest hole, any female, and then they all try to mate with that female.
• 13:13
  And she lays eggs.
• 13:14
  And sometimes there's more than one female who lays eggs in a nest hole.
• 13:18
  Really?
• 13:19
  So the females will sometimes cooperate even?
• 13:21
  Yeah.
• 13:21
  I think to the extent that the females are laying, are sharing the nest hole.
• 13:26
  Yeah, yeah.
• 13:27
  But this brings up the question of, you know, where cooperation starts being competition and conflict as well.
• 13:36
  And with eclectus parrots, it's just fascinating because they have a very skewed sex ratio.
• 13:42
  I think one of the most skewed sex ratios of any bird we know.
• 13:46
  So lots more males than females.
• 13:49
  And sometimes the skew seems to happen really early on.
• 13:55
  We don't know exactly how they do it, but some of it seems to be infanticide by mom.
• 14:01
  Oh, interesting.
• 14:02
  She only lays two eggs at a time.
• 14:04
  So once they hatch, they're really easy to sex because of these color differences.
• 14:08
  And there's...
• 14:10
  suggested evidence that mom will kill off daughters more than she kills off sons.
• 14:15
  Wow.
• 14:16
  There's also a suggestion that she can manipulate, mom can manipulate the sex ratio of her kids before she even lays the eggs.
• 14:24
  Right.
• 14:25
  And this might be easier on birds because, you know, as you know, birds, the females are the ones with the two different sex chromosomes, not the males.
• 14:34
  And, uh, yeah, it's a very skewed sex ratio.
• 14:38
  So you end up with all these extra males who are just dying to have, to father something or someone.
• 14:46
  And so they're totally willing to share the paternal care and the paternity of a single nest hole of chicks.
• 14:54
  That's interesting.
• 14:54
  Why are their nest holes so limited?
• 14:56
  I guess like parrots typically don't excavate cavities.
• 15:00
  So they're reliant on cavity production by some other species or what?
• 15:04
  Just the right kind of tree maybe.
• 15:06
  Oh, okay.
• 15:07
  Huh.
• 15:07
  I don't know.
• 15:07
  Yeah.
• 15:09
  They're very fussy, I suppose.
• 15:11
  Yeah.
• 15:12
  They look like they'd be fussy birds.
• 15:13
  Yes, they do.
• 15:15
  You see them and you're like, oh, a little fancy.
• 15:18
  Yeah.
• 15:23
  In other systems where there's a resource that is limited, like marshes, for example, are these patchy habitats across the landscape that male marsh wrens, for example, can take over a lot of a marsh.
• 15:35
  And then you get multiple females nesting within that male's territory because...
• 15:39
  They just need a marsh to breed in.
• 15:40
  And it's either, you know, that there's multiple females with one male or you don't get to breed.
• 15:46
  So it's kind of similar in the sense that there's this controlled resource by one sex that leads the other sex to, you know, quote unquote, be okay with like sharing a mate with other individuals.
• 15:57
  Yeah.
• 15:58
  I mean, I guess the other classic is the red-winged blackbirds, right?
• 16:01
  Yeah, yeah.
• 16:01
  Where the females could do this.
• 16:03
  It's almost like the females are doing this mental calculus of, is it better to be on a very good territory, but be wife number two, female number two, so you don't get as much help.
• 16:14
  But still, maybe your odds of raising more chicks are still better than being the only mate, social mate of a male with a subpar territory.
• 16:24
  Yeah.
• 16:24
  Yeah.
• 16:25
  In red-winged blackbirds, I guess that's probably the most common or most familiar bird to folks listening.
• 16:30
  Do males help with parental care?
• 16:32
  So if they have like multiple females within their territory, they're actually provisioning to all of those nests, but I guess at lower frequencies?
• 16:40
  Yeah, I think so.
• 16:41
  Although in some birds, this is one of my favorites.
• 16:45
  In one of the flycatchers in Europe, I think there was a study where males would provision based on how much they thought they'd sired the chicks.
• 16:56
  And you can really manipulate this by temporarily kidnapping the male so that he knows he didn't sire those.
• 17:04
  He didn't fertilize those eggs.
• 17:06
  And then he reduces his care on those nests.
• 17:10
  Interesting.
• 17:11
  So that's part of the conflict.
• 17:14
  part of this deal.
• 17:15
  Yeah.
• 17:16
  We've talked a lot about these systems where you have one of one sex and multiples of other sex.
• 17:21
  There's a lot of birds that have these crazy elaborate mating displays.
• 17:26
  Things like bowerbirds that build, basically build like art installations to attract a female or mannequins and the famous ones have, I mean, mannequins are crazy.
• 17:34
  They do all these amazing displays, including moonwalking.
• 17:38
  Why do these absurdly elaborate courtship displays evolve?
• 17:41
  Like what about mating system allows that to happen?
• 17:44
  it's a winner-takes-all situation typically.
• 17:46
  So whoever's most attractive, given their displays or their songs or their plumage or all of the above, it tends to be one or two individuals out of a large population so that they then pass on their genes to a very large proportion of the next generation.
• 18:08
  Wow.
• 18:09
  And that's what allows this kind of very elaborate stuff to evolve.
• 18:15
  Why they do that is what everyone loves to try to explain.
• 18:20
  And I think one of my favorite explanations is, bring it all the way back to Darwin, when he proposed the idea of sexual selection, where it was purely arbitrary.
• 18:30
  It's just a fashion that evolves or like an aesthetic preference.
• 18:35
  And that a very famous evolutionary biologist named Ronald Fisher managed to model, and we tend to call it the sexy sun hypothesis these days, sexy sun hypothesis these days, because mostly it's females doing the choosing of very elaborate male plumage.
• 18:54
  I just love that idea because it's so arbitrary that you could just get from...
• 19:02
  a single fashion preference in a few generations amplified over the generations into very large differences in which sex has ornaments and which doesn't, and the elaborateness of those ornaments, purely based on the preference as well as that ornament evolving over time.
• 19:26
  to become more and more elaborate until it sort of breaks down because you just can't possibly escape from predators with such a large tail or shining a huge beacon of shiny feathers into everyone's eyes or something like that.
• 19:41
  So there's always a trade-off.
• 19:43
  The other main flavor of explanation, which again is not mutually exclusive, is that these very costly displays
• 19:57
  And so you could say, oh, it's a handicap because only someone who's so...
• 20:04
  strong or well defended against parasites or fast or whatever, is able to mount such an expensive display.
• 20:13
  Like you can only afford a Porsche if you genuinely have money.
• 20:17
  You can't just steal a Porsche.
• 20:19
  Yeah.
• 20:19
  Well, you can, but you would get put in jail.
• 20:22
  Or it would break down.
• 20:23
  It would break down fast.
• 20:26
  You wouldn't garner all those matings.
• 20:28
  Exactly.
• 20:28
  Exactly.
• 20:29
  You would be limited.
• 20:30
  Yeah.
• 20:31
  Yeah.
• 20:33
  So there's that part of the elaborate display explanation as well.
• 20:37
  But I really like the idea that based on just arbitrary preference alone, some of this could happen.
• 20:45
  And in a lot of these systems, like where you have these incredibly elaborate courtship displays evolving in males, the young of these birds are often altricial, but females don't have that many, right?
• 20:56
  Like I think typically in birds of paradise, it's just...
• 20:59
  a couple chicks.
• 20:59
  I don't actually know for bowerbirds, but they also live in parts of the planet where there's lots of resources.
• 21:04
  So like they're living in tropical rainforest areas or resource rich areas where, you know, thinking back to talking about
• 21:12
  well, it takes two parents to raise all these chicks because they require a lot of investment.
• 21:17
  In a lot of the habitats where we see these super elaborate males and females doing all the parental care, there's a lot of food resources available, right?
• 21:25
  Right.
• 21:25
  Or they're precocial.
• 21:27
  Right.
• 21:27
  The independent kids, like all the lacking grouse species, all those dancing chickens.
• 21:36
  We love our dancing chickens out here in Colorado.
• 21:39
  But yeah, so like peacocks and all the really crazy looking pheasants, all of those also have precocial offspring.
• 21:46
  So either they have precocial offspring that don't need a lot of care and then you get these elaborate males evolving or they have altricial offspring, but they live in places where it's really easy to get a lot of food for your chicks, which is...
• 21:58
  I think so.
• 21:59
  Yeah, neat to think about how much food resource availability and just how difficult it is to raise chicks then influences the evolution of these different reproductive strategies.
• 22:09
  And in this case, we're talking about these elaborate, typically elaborate males.
• 22:13
  Yeah, although of course, in the tropics, a lot of the females sing as well.
• 22:18
  Yeah, that's true.
• 22:19
  So there's definitely back to your question about, is it really the female doing the choosing all the time?
• 22:27
  There's definitely a lot more examples of the typical mating system we're more used to, the social monogamy, where the displays are not so one-sided.
• 22:37
  They could be elaborate, but they're just not so one-sided.
• 22:40
  So both sexes have the, like blue-footed boobies, both sexes show off their blue feet and they choose each other.
• 22:48
  Or another favorite example of mine is greater flamingos.
• 22:53
  where I think, I don't know if both sexes do this, but the females definitely attract males based on how pink they are, how red they are.
• 23:02
  And they even apply rouge to themselves from a special green gland.
• 23:08
  I find that so cool.
• 23:09
  That's really cool.
• 23:10
  I didn't know that.
• 23:11
  Makeup.
• 23:11
  Yeah.
• 23:12
  That is an example of a fairly honest signal, I think, where if the bird is very pink or reddish,
• 23:19
  It's probably an honest indicator of how healthy it is.
• 23:24
  The blue color of a blue-footed boobie's feet is really important.
• 23:27
  And it's a combination of structural color, which is the blue, and then carotenoids, which are yellow.
• 23:33
  And so aquamarine colored feet indicate high quality because they're getting all these carotenoids from their diet.
• 23:38
  And if you take a male blue-footed boobie and you prevent him from accessing food for a while and then put him back with his mate, his foot color changes enough that her next egg is smaller.
• 23:50
  Like she reduces investment really in real time by evaluating the color of her mate's feet and being like, oh, I'm not going to invest as much.
• 24:00
  And if you do the opposite, like if you serve the female or restrict access to food for a little while, her foot color changes enough that he will display to her less.
• 24:10
  So it is really this reciprocal and dynamic signaling with these blue feet.
• 24:15
  And with blue-footed boobies, it's even cooler.
• 24:17
  I don't know if you've, have you seen them in the wild?
• 24:19
  Yes, yes.
• 24:19
  Yeah, so the females are bigger.
• 24:21
  It looks like their pupil's bigger from a distance.
• 24:24
  And you can tell their sex from a distance just by looking at like, oh, that one looks like it has a bigger pupil.
• 24:29
  But if you look at it up close, it doesn't have a bigger pupil.
• 24:31
  It has dark pigment in the iris around the pupil that makes the pupil look bigger.
• 24:37
  But it's not actually bigger.
• 24:39
  Which if you think about like the belladonna hypothesis, so this idea that dilated pupils indicate...
• 24:45
  sexual arousal.
• 24:47
  I feel like blue-footed boobies have other aspects of sexual selection.
• 24:51
  Isn't it cool?
• 24:52
  And there's like no way to test it.
• 24:53
  Like you couldn't put contacts in the eyes of these females.
• 24:56
  You're just making me wonder that.
• 24:59
  How could you figure it out?
• 25:00
  But it's fascinating.
• 25:01
  Manipulate.
• 25:02
  Wow.
• 25:03
  Yeah.
• 25:04
  And I mean, with blue-footed boobies, it's already like, they have the blue feet, the crazy dances.
• 25:08
  So why wouldn't they have other aspects of sexual selection that were kind of run away?
• 25:12
  But in this case, it would be a female signal that males were maybe cueing in on this perceived larger dilated pupil.
• 25:19
  But I don't know.
• 25:20
  Yeah.
• 25:21
  I've thought about ways we could test it.
• 25:22
  But everything I come up with
• 25:24
  I think these plunge diving birds.
• 25:28
  Yeah.
• 25:28
  That's true.
• 25:29
  The contact would fly right off.
• 25:30
  Yeah, exactly.
• 25:32
  Exactly.
• 25:32
  Yeah.
• 25:34
  But I love that as an idea of essentially how to deceive.
• 25:37
  Yeah.
• 25:39
  Potentially.
• 25:40
  Yeah, definitely.
• 25:41
  And it's interesting that like the belladonna hypothesis, I think, has mostly been studied in mammals.
• 25:48
  And then to think that it...
• 25:49
  But like if you've ever had a pet parrot, their pupils are just like dilating and contracting it.
• 25:56
  I don't know, as they interact with you and stuff.
• 25:58
  I've seen that.
• 25:59
  Yes, yes.
• 26:00
  Yeah.
• 26:01
  Wow.
• 26:02
  How do other parrots feel about that?
• 26:03
  I don't know.
• 26:04
  What's the...
• 26:06
  I know when my budgie was really excited about giving my earlobe some food because he was confused about who his mate was, his pupils would be going nuts.
• 26:14
  So there's got to be something there.
• 26:16
  You know, you could test that with parrots because I just saw a study with some example of parrots calling each other, making friends online.
• 26:27
  Yeah.
• 26:28
  Really?
• 26:28
  And having favorites to talk to on FaceTime or on video chat.
• 26:33
  Really?
• 26:34
  Because they would get lonely as single parrots at home with their human family.
• 26:40
  And, you know, they'd like to hang out with other parrots.
• 26:43
  So they would have their favorites about who to call.
• 26:46
  That's...
• 26:47
  Which is so predictably parrotsy.
• 26:49
  Yeah, that's so weird.
• 26:50
  You might understand this.
• 26:52
  But you could then, I suppose, digitally manipulate...
• 26:58
  the pupil size or the the speed with which the fellow parrot was expanding and contracting its pupils yeah
• 27:09
  And figure out what their pupils are saying to each other.
• 27:12
  Yeah, yeah.
• 27:12
  Huh.
• 27:13
  That would be so cool.
• 27:13
  That would be really cool.
• 27:15
  Man, there's all these interesting...
• 27:16
  I think the elaborate piece of all these bird displays really fascinates us just because it's so visually obvious, right?
• 27:22
  Humans are so visual.
• 27:23
  But I wanted to talk about this little brown bird that doesn't have an elaborate courtship display and briefly came up in episode one when we were talking with Carrie, so the dunnock.
• 27:33
  Yeah.
• 27:36
  from a mating systems perspective, can do everything at once.
• 27:40
  And so could you tell us a little bit more, dive more into this, Danik?
• 27:43
  Because I know you really like them as well.
• 27:46
  I do.
• 27:46
  I don't know how you know I like them.
• 27:48
  Is it because I keep writing about them?
• 27:49
  I think it's probably because you keep writing about them.
• 27:52
  I tried to do my PhD with Nick Davis, who is the person we can credit for essentially...
• 28:00
  all these revolutionary ideas about mating systems.
• 28:04
  And I thought I would go back to his very seminal paper because the title says it all, Cooperation and Conflict Among Danucks.
• 28:15
  Mm-hmm.
• 28:16
  I should read this because it's just so funny.
• 28:18
  He quotes this at the beginning of his paper.
• 28:21
  Unobtrusive, quiet and retiring without being shy, humble and homely in its deportment and habits.
• 28:29
  Sober and unpretending in its dress while still neat and graceful.
• 28:33
  The Danuk exhibits a pattern which many of a higher grade might imitate.
• 28:38
  with advantage to themselves and benefit to others through an improved example.
• 28:43
  Okay, so Nick is quoting here, right?
• 28:45
  And then he says in the next paragraph, it is perhaps unfortunate that the Reverend F.O.
• 28:51
  Morris urged his parishioners to emulate the life of the dunnock or hedge sparrow, because the most striking feature of this small passerine bird is its extraordinary sexual behavior and an extremely variable mating system.
• 29:07
  Yeah.
• 29:08
  I love that.
• 29:08
  I mean, I think that says it all.
• 29:10
  It's like so good.
• 29:11
  So then the rest of the time, Nick is basically there trying to figure out why this mating system is so variable.
• 29:20
  And it all comes down to conflict between the sexes, sexual conflict.
• 29:24
  The idea that both males and females want to get as many chicks into the next generation as possible.
• 29:31
  And if you're a female...
• 29:33
  that's happening partly because you have a larger territory with better food, if you're a strong female.
• 29:40
  Also, if you can get more parental care, more males to help you.
• 29:46
  And so if a female has a territory that is pretty large, then it's impossible for a single male to defend that territory.
• 29:57
  And that's when you tend to get polyandry, when you have one female and you've got two males or more.
• 30:04
  but usually two males trying to duke it out to see who's going to be the senior male and father more of her offspring.
• 30:13
  And there's tons of competition between those two males for access to the female, as well as, you know, they will try to titrate how much they care for the chicks based on who got to mate more with her.
• 30:26
  That's crazy.
• 30:27
  And there's typically an alpha and a beta male.
• 30:29
  And the polygynandry often happened when
• 30:32
  it was impossible for the males and the females to exclusively defend their territories.
• 30:37
  So then you'd end up with a shared mating system of everyone, two males and two females sharing things.
• 30:46
  Obviously, the males are not passive in all this too.
• 30:49
  So their preference would be to have a female exclusively mating with them.
• 30:54
  Yeah.
• 30:56
  And they do a lot of things to try to make sure that's the case.
• 31:01
  If they can't do it by guarding the territory, then they do it by guarding the female as much as they can.
• 31:07
  And by doing this amazing cloacal pecking.
• 31:11
  Oh, yeah.
• 31:11
  I've seen videos of that.
• 31:12
  Which I got to see in my garden in Cambridge.
• 31:16
  You know, I had a pair of dunnocks in my garden in Cambridge and I was like, oh, I really hope I get to see this.
• 31:23
  Weird behavior.
• 31:25
  So with most birds, especially if they're birds like dunnocks, they just touch cloacas.
• 31:33
  In fact, I think sometimes it's called a cloacal kiss.
• 31:35
  It's very brief and that's it.
• 31:37
  The sperm is transferred and things move on.
• 31:42
  Um, but yeah, Nick has this really fun anecdote of seeing a female Danik doing her little wing, um, display, wing flapping thing and the male coming up.
• 31:56
  And instead of just mating with her, he pecks very vigorously at her cloaca for a long time, a few minutes, which seems like a long time if you're watching a bird.
• 32:07
  I mean, a few minutes keeps going.
• 32:09
  It's like longer than the cloacal kiss has.
• 32:12
  Right, way longer.
• 32:13
  And she eventually extrudes a little glistening packet.
• 32:19
  Oh, interesting.
• 32:20
  It's sperm from whoever mated with her before that.
• 32:25
  And especially in those systems, in those situations where there's two males with one or more females in the same general area, in the same territory, they're
• 32:38
  It's really worth making sure that your rival's sperm is not in there before you mate with a female.
• 32:47
  And you got to see this in your garden in Cambridge.
• 32:50
  I kept looking for it.
• 32:51
  So that was very exciting.
• 32:53
  We're so biologists.
• 32:55
  We're just curious about the curious things.
• 32:57
  I would have wanted to see that too.
• 32:58
  So I'm glad you got to see it.
• 33:01
  We've reached the part of the show we call That's BS or That's Bird Stuff, where we give our guests an opportunity to debunk a myth that ruffles their feathers.
• 33:07
  So Wenfei, what do you want to call BS on?
• 33:10
  Specifically related to the title of the book, Bird Love.
• 33:13
  I had a...
• 33:15
  review, I think, at some point, complaining that there was nothing about love in the book.
• 33:21
  And that made me think, oh, you must be consuming some really wonderfully sanitized hallmark version of human existence to be...
• 33:35
  Nature is very amoral, is the take home.
• 33:38
  So any kind of relationship that looks cooperative, there's always the other side of it with conflict and cooperation.
• 33:47
  We pledge allegiance to each other and we will be faithful and love each other forevermore.
• 33:52
  It's complete bunk.
• 33:55
  Awesome.
• 33:56
  Well, thanks so much for joining us on the podcast today.
• 33:58
  I really appreciate it.
• 33:59
  This is such a fascinating topic and yeah, it's always really fun to talk about.
• 34:03
  So thanks for taking the time.
• 34:05
  Thank you.
• 34:09
  Birds are dinosaurs, and around here we like our snacks, so we end each episode with a dinosaur nugget.
• 34:14
  Today's nugget is birds didn't invent the open relationship.
• 34:17
  They never needed the rules in the first place.
• 34:19
  We're the ones who built a whole vocabulary just to describe what they've been doing all along without a second thought.
• 34:25
  Bird relationships are so much more interesting and complicated than the majority of us ever imagined.
• 34:29
  We created OK, but birds, because birds are cool.
• 34:33
  Case in point.
• 34:34
  Okay.
• 34:34
  That's a wrap on this week's episode.
• 34:36
  Okay, but did birds originate the open relationship?
• 34:39
  If you liked this episode, share it with a friend.
• 34:41
  Whether they own binoculars and are bird obsessed or may just be bird curious, help us get the word out.
• 34:45
  We'll catch you next time.
• 34:47
  Bye.
• 34:52
  Okay, but birds is hosted by Scott Taylor with production and creative by Zach Carl.