IRA FLATOW: This is “Science Friday”. I’m Ira Flatow. I can’t believe I’m asking this. I’m asking you to consider the city pigeon. Yes, it’s the bird that roams the streets of urban areas like stray dog or cat.

It eats garbage. It poops in our window sills and nests in our eaves. And you may have a certain derogatory nickname for pigeons and I bet I know what that is. But before you write these birds off her good, producer Christie Taylor is here with a plea, to just spend some time watching them. Hey there, Christie.

CHRISTIE TAYLOR: Hello, Ira.

IRA FLATOW: Now, I know you’re a member of our small but mighty, sci-fi pigeon fandom.

CHRISTIE TAYLOR: Yep, that’s right.

IRA FLATOW: Convince me why are we watching pigeons?

CHRISTIE TAYLOR: First of all, it is a long story and second of all, there is quite a bit of poop involved. I hope you’re still with me.

IRA FLATOW: Poop and pigeons. Oh, why am I so surprised? You’re going to need a little bit more arm twisting on this one.

CHRISTIE TAYLOR: OK. Well, hear me out. Pigeons have actually a millennia old relationship with us. They’re not just wandering around our streets, but we domesticated them, much like dogs and cats. And we enjoyed them both as a food item and a fertilizer for thousands of years. That’s where the poop comes in.

IRA FLATOW: I see. They poop so we can eat.

CHRISTIE TAYLOR: As a result, we now have feral pigeons, the escaped offspring of our tame livestock, in every major city in the world. Rosemary Mosco is a science cartoonist and author and her latest book is A Pocket Guide to Pigeon Watching. It’s all about hour long, long history with these birds and what you can observe about them when you see them out and about, like how to find baby pigeons.

And the first thing we talked about was the big W, why pigeons deserve more love than they get.

ROSEMARY MOSCO: Personally, I got excited about pigeons really, really early on because I was a bird watcher and I lived in a bunch of major cities. So when you’re a bird watcher and you’re living in an urban environment, you notice the pigeons. So I always thought they were kind of cool.

But then I started to delve into their history and I realized how incredibly misunderstood they are and how unfairly we’ve been treating them. And that just blew my mind. And I felt like I really needed to tell everyone that hidden history.

CHRISTIE TAYLOR: So you’re talking about pigeons in our streets, they’re descendants of domesticated pigeons. You really want us to think of them like stray cats or dogs, right?

ROSEMARY MOSCO: Yeah, exactly. There are so many similarities. With pigeons, there are thousands and thousands of years of domesticated history, just like when we domesticated the dog or the cat thousands and thousands of years ago, for various purposes. But yeah, we don’t know exactly when it happened, and it probably happened in lots of different places and lots of different times, which is also how it happened with dogs and with cats.

With pigeons, many people have completely forgotten that they were once our precious domestic friends. And I think that’s really wild.

CHRISTIE TAYLOR: You keep mentioning dogs and cats. We know that those animals have helped us drive away vermin, protect our settlements, even help us hunt our own food over time. And there’s also companionship, of course. What did we get out of keeping pigeons?

ROSEMARY MOSCO: Right. When you look at a pigeon, you don’t think, oh gosh, look at that. I can ride on that. Or I could protect my crops or something. But they are so, so, so incredibly useful. So I like to think of them as the Swiss army knife of birds. They were probably initially domesticated for their meat. People all over the world still eat pigeons and North Americans ate them up until pretty recently.

But there are so many other uses. Their poop is a really important fertilizer. They carry messages on their legs long, long, long distances. You can raise them, and you can even breed them in all sorts of cool shapes and colors and patterns, again, a lot like dogs.

CHRISTY TAYLOR: I want to talk about pigeon poop because that was one of the things that started out maybe as a side benefit of keeping pigeons but turned into a whole other reason to keep them. Is not true?

ROSEMARY MOSCO: Yeah, that’s absolutely true. Pigeon poop was really like brown gold. So pigeon poop is a really, really potent fertilizer. And it’s excellent, especially, if you’re living in an area with desert soils that maybe need a little bit more of a nutrient influx. It’s great stuff.

So for a long time people in the Middle East and in the Fertile Crescent were using pigeon poop to grow all kinds of beautiful fruits and vegetables. And then that usefulness of pigeon poop sort of exploded, not to use a pun, when people discovered that there’s this stuff in pigeon poop called saltpeter, that can be used as an ingredient in gunpowder. And so in England, especially in the 17th century, these gentlemen called salt Petermann were marching across the country at the behest of the king and knocking over dove coats and digging up all of the pigeon poop. And this was ruffling a lot of feathers.

CHRISTIE TAYLOR: You also write that pigeons can tell us part of the story about even European colonialism. Why is that?

ROSEMARY MOSCO: So back in the day in North America, there was a species called the passenger pigeon. And I’m sure many, many, many people have learned about the passenger pigeon and the tragedy of how this species was destroyed. For many, many generations, they were sustainably managed by Indigenous people who lived here and they were eaten. And so when colonists came over, they went hey these things look really delicious, and destroyed a lot of those passenger pigeons and they sadly, went extinct.

And the really wild thing is that those colonists considered pigeons to be so important, that they brought over their own city pigeons. So essentially, there was a replacement of this passenger pigeon. Nowadays, we’ve forgotten why we even brought over the pigeons because we’ve eaten factory farmed chicken for a while. So it’s this history of replacement and then forgetting that I think tells us a lot about colonialism.

CHRISTIE TAYLOR: I want to talk then about the city pigeons that we see today. They often have this one very standard look, blue with that black bar on the wing, beautiful iridescent neck. But there’s a lot of variety that we actually see if we really look closely at the pigeons in our cities. Different colors, different patterns. Where does all of that come from? Should we assume that they’re crossed with something like a fancy breed of some kind?

ROSEMARY MOSCO: Yeah, absolutely. This is one of the most remarkable things about pigeons. And I think it gives pigeon watching its real focal point, is that, again, much like with groups of feral dogs, you’ll see lots and lots of different shapes and sizes and colors in our city pigeons. And that’s purely because we took a whole bunch of breeds, some of them escaped, and they cross breed.

And so you’ll get all kinds of beautiful colors, from browns to whites, to different blues. And you’ll see these different colors sort of in different levels of intensity and in different patterns. And that’s totally because we took, say, some chihuahuas and some Great Danes and all these different purebreds, and they interbred on our streets.

And in fact, there’s something else going on, which is that at some point, again, kind of lost to the myths of time, folks crossbred this species in Africa, called the speckle pigeon, with our city pigeons. And so you’ll see a lot of city pigeons with these speckly wings, and that’s because of this hybridization that happened at some point, that people did, we don’t know why, and those genes are in there. So our history is written all over our city pigeons.

CHRISTIE TAYLOR: That’s amazing. The speckle ones are some of my favorite ones to see, actually.

ROSEMARY MOSCO: Yeah, they’re beautiful. But there really is just this incredible variety of all of these colors. And not all of these varieties did super well when they would escape into the city. So you won’t see some of those more fantastical varieties. But you will find, for example, city birds that have feathers on their legs. And that is one of those things that comes from those purebred birds. And probably gives them a bit of an extra toasty warmth in the winter.

CHRISTIE TAYLOR: Let’s talk about anatomy for a second. I couldn’t help but notice that one thing that they do very differently from mammals, is how they breathe. Pigeon lungs, as you write, don’t expand. How the heck does that work?

ROSEMARY MOSCO: So bird lungs are paired just like our lungs but they don’t open and close. There are these air sacs all around the lungs that channel the air through the lungs. And these air sacs stretch into the wings. They’re really, really amazing. There’s tons and tons and tons of them.

And so what this does is it makes birds really, really, really efficient at pulling oxygen out of the air and this helps fuel their flight. So I would say that their respiratory system is truly, truly incredible.

CHRISTIE TAYLOR: Perhaps on the too familiar side of things, though, they also make milk, which first of all, that’s weird. Second of all, maybe kind of gross. Third, I don’t see any little pigeon udders, as far as I can tell, so what’s going on with that?

ROSEMARY MOSCO: Yeah, one of my favorite things to do is to tell people that pigeons make milk and then sort of pause. And I know exactly what’s going on in their minds because they’re imagining where are the udders? Which is totally reasonable. They don’t have udders.

They do make milk. It has a lot of similarities to human milk but it’s produced in this area of the esophagus called the crop. So it’s sort of secreted into this area and puked into their baby’s mouths.

CHRISTIE TAYLOR: OK, OK.

ROSEMARY MOSCO: But it’s got proteins and fats and it’s stimulated by a hormone called prolactin. And it’s really essential for their baby’s development for the first few days. It is apparently chunkier than cow’s milk. And so I wouldn’t recommend getting yourself a cup of it. But also it would be really hard to milk a pigeon so you don’t need to worry about doing that.

CHRISTIE TAYLOR: Well, I stand by the gross assessment from earlier. OK.

ROSEMARY MOSCO: That’s fair.

CHRISTIE TAYLOR: Why don’t pigeons fly more? I feel like I’ve seen them walking up stairs, crossing the street in the crosswalk, people have observed them on the subway sometimes. What’s up with that?

ROSEMARY MOSCO: Pigeons really are walkers. They fly very, very, very well. They’ll fly to and from their nests or they’ll fly in response to a predator. But flying is pretty exhausting. I mean, why aren’t we all running around all the time at top speed?

CHRISTIE TAYLOR: Fair question.

ROSEMARY MOSCO: I mean, it’s an essential tool but pigeons really did evolve to be ground foragers, which I think is a lot of why people think they’re sort of gross, is that they’re just walking all around on the ground. And they are usually walking around on the ground looking for grain and that sort of thing. And they’ll even sometimes sleep on the ground.

And then when they nest, they’ll nest on flat surfaces. So they are not birds of the forest and you’ll never see a pigeon nesting in a tree, or very, very rarely.

CHRISTIE TAYLOR: Is there a behavior that you haven’t yet managed to see that you know about that you think is really cool?

ROSEMARY MOSCO: So you’ll often hear pigeons sort of clapping when they take off. And what they’re doing there is they’re flinging their wings overhead and kind of slapping the backs of their wings together, potentially to tell other pigeons, hey, there’s something scary here. But there’s another reason that they clap. The males do something called a post copulatory display, which is something that a lot of animals do and maybe even some humans, and we don’t really know why they do this.

The pigeons will mate and then the male pigeon will take off and he will fly back and forth and clap for himself, basically. So he’ll be flying along and do a series of like, wahoo, I’m so great, claps in the air.

CHRISTIE TAYLOR: If we can’t see the pigeons but we can hear them, is there anything that they do that’s beyond the usual, just cuckoo, I’m here.

ROSEMARY MOSCO: Yeah. Their vocal rule is surprisingly complicated. I mean, they don’t sing fancy, fancy songs but they make a lot of different sounds. So I mentioned the clapping. There’s also a wing whistle, where they’ll take off and they’ll make the sort of whistling sound that tells the other pigeons there’s something dangerous and we all need to take off now.

And then there are the cooings. So there’s one called the display coo and that’s the coo that you will hear when a male pigeon is kind of bobbing up and down and showing off to his pigeon wife. And the female pigeons will sometimes do it too. And that’s kind of the standard coo. So that’s really hard for me to do. It’s sort of like [BIRD SOUNDS]

CHRISTIE TAYLOR: Oh, wow. That was incredible. Thank you.

ROSEMARY MOSCO: Thank you so much. I don’t think I’m going to win any pigeon wives.

CHRISTIE TAYLOR: Who knows? Maybe she’ll come someday.

ROSEMARY MOSCO: Someday. Wistfully looking out at the window. But then they make another coo and this one is truly wild. So I first heard this when I was staying at a friend’s house in New York City. It’s called the advertising coo. And a male pigeon will make the sound when he has found a really cool spot for a nest. So that sounds like this. It sounds like [BIRD SOUNDS]

So it sounds like a guy going woo, basically. And that is their way to say, hey, check it out. I have a really cool nest spot. So you probably will hear that at some point. And it’s not a person. It is a pigeon.

CHRISTIE TAYLOR: Is that check out this Zillow listing that I just found?

ROSEMARY MOSCO: Exactly. Like, oh, we may never actually rent this place or purchase this place. It’s $5 million. But look how good it is. We could raise so many pigeons here.

CHRISTIE TAYLOR: Just a quick reminder, I’m Christie Taylor and this is “Science Friday” from WNYC Studios. Talking to author and illustrator, Rosemary Moscow, about her new book urging you to go watch pigeons.

So as you mentioned at the start of this conversation, pigeons kind of get a bad rap and some of it has to be because they’re on the ground, eating our trash. But there’s also this fear that they’re making us sick. Is that legitimate in any way? Should we still maybe handle with care if we’re lucky enough to even touch a pigeon?

ROSEMARY MOSCO: One thing that I found really comforting about reading a whole lot of different studies about pigeons causing illness is that it’s really a relatively rare thing. Pigeons can carry some illnesses they could potentially pass to us. Definitely be very careful if you work with pigeons a lot or if you have any conditions that result in being immunocompromised. But pigeons in the park are really not going to cause you a lot of issues.

There’s a real misconception there and it was partly born in the 1960s when pigeons at that point had sort of fallen out of favor. They were sort of obsolete technology. We weren’t really eating them. We weren’t using their poop as fertilizer. We were sort of over them. They were kind of like fax machines are today.

And at the same time, there were all these feral birds everywhere, so people sort of thought, ew grow. These creatures are in our space. In the 1960s in New York City they were blamed for a meningitis outbreak. And it was this tragic thing. A couple of people passed away.

It was not because of the pigeons, but city officials said this kind of miasma of pigeon filth was spreading all throughout the Northeast and there was a lot of fear mongering. And that’s partly why we think pigeons are really gross. But they’re really not the major health risk that we all worry they are.

CHRISTIE TAYLOR: Do you have any last pro-pigeon propaganda to throw our way?

ROSEMARY MOSCO: Yeah. One thing that I love to stress is that pigeons used to be considered a luxury item, basically. So for hundreds and hundreds of years in places all over the world, they were considered something that only the rich had, kind of like a Ferrari of birds. And in some places they were used to reinforce class distinctions because only the rich were allowed to keep pigeons and the poor we’re not.

I’m not saying we need to go back to that kind of horrendous situation. But I think it’s really important for us to think about how we used to think of animals and how we think of animals now and how there’s always kind of changes throughout history. So pigeons are super cool and fun to watch and also, they can tell us a lot about ourselves. So I think their gifts just keep on giving, even if one of those gifts is crap.

CHRISTIE TAYLOR: Well, I’m going to leave it there. Thank you so much Rosemary.

ROSEMARY MOSCO: Thank you so much. This was really fun.

CHRISTIE TAYLOR: Rosemary Mosco, author of the new Pocket Guide to Pigeon Watching. And if you are as excited about pigeons as Rosemary and I and maybe you have a big brain full of pigeon facts, you can catch Rosemary at next week’s sci-fi virtual trivia night. The winner gets two free copies of her book, A Pocket Guide to Pigeon Watching. And even if you didn’t win, I can guarantee you’ll have fun with the nerd flock.

That’s Wednesday, January 26 at 8:30 PM Eastern. To learn more, visit our website sciencefriday.com/trivia.

IRA FLATOW: Huh. Sounds like I’m going to have to sneak into that, try my luck. I got to admit it, Christy, you really made a surprisingly good case for pigeons.

CHRISTIE TAYLOR: Thanks, Ira. You can’t see, but I am positively preening right now.

IRA FLATOW: You missed a spot. Christie Taylor, sci-fi producer and staunch member of team pigeon. Thank you for joining us.

CHRISTIE TAYLOR: You’re welcome.

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