E25: Okay, but… boobies!

Scott Taylor: Okay, let's get the obvious out of the way. Yes, this episode is called Okay, but... Boobies, and I'm going to say boobies about 30 more times in the next half hour. No, we're not going to make it weird. Boobies are a real group of birds with a real Spanish derived name. And once you know what they actually are, the joke kind of stops being a joke. The booby most people picture is the blue footed booby. You probably haven't seen one in person, but you have absolutely seen one. Bright, almost cartoon blue feet, a goofy high stepping mating dance that has been clipped and reposted into oblivion. A face like it just walked into a room and forgot why. It's the kind of bird that gets stuck in your head as a personality first and as a species second. Which is, I think, why most people picture exactly one booby and stop there. There are more though. The red footed, the brown, the masked, the Nazca, and the Peruvian Abbott's booby. If you're feeling generous about whether it counts, which depends on which taxonomist you ask on which day. And they're close cousins, the northern gannet, the Cape gannet and the Australasian gannet, which are the same body plane and a colder coat. So why booby? The name comes from the Spanish bobo, meaning fool, silly or clown. And to be fair, the nickname kind of earns itself. But only on land. On a rocky island surrounded by guano and ticks. A booby is awkward. They waddle. They show off their feet to each other with their body language of someone trying to win an argument at a bar. Spanish sailors saw that and decided, fool. Done. Got it. But fool is the worst possible word for what a booby actually is. Get one in the air or in the water and the whole story changes. Boobies are streamlined, missile shaped plunge divers. They climb, fold their wings and drop. They hit the water at speeds that should rearrange anyone's anatomy. And then they swim with their wings after fish that are also moving. They eat anchovies, sardines, squid, and in one group, a fish that has decided the only way to survive is to leap out of the ocean and glide. Boobies have figured out how to deal with that too. The whole family has built a life around being the apex predator of a column of water that was completely unfair to begin with. Not Foolish, specialized to the point of art. I have a personal stake in this one. Boobies were one of the first wild birds I ever did real field work on on several guano islands off the central and northern coasts of Peru. With the guests you're about to meet. Dr. Carlos Zavalaga, marine biologist and director of the Marine Ecosystem Research Unit and Peruvian Seabird Group at Universidad Scientifica del Sur in Lima, has spent more than 30 years studying seabirds of the Humboldt Current. And he is one of the people who taught me how to study them, too. After the break, Carlos walks us through what makes the booby family the way it is and the part of their biology you really only appreciate when you watch them hunt. We get into how multiple booby species live in the same ocean without eating each other out of house and home. And we talk about what's happening to these birds right now off the coast of Peru, where the pressures stacking up on them are getting more frequent, harder to recover from, and harder to ignore. Stay tuned. Well, welcome back, everyone. I'm really excited to have Carlos with me today to talk all about boobies. And it's good to see you again, Carlos.

Carlos Zavalaga: Thank you, Scott.

Scott Taylor: Yeah, we've spent some time together in the field. Actually, some of my first field experiences were with you in Peru, so I'm excited to revisit some of that today. This group of birds, boobies, are a group of birds most people have heard of, usually because they think maybe blue feet or a funny name. And I'm wondering if you could tell us a little bit more about this really cool family of birds.

Carlos Zavalaga: Okay, so these birds are seabirds, of course. They are completely marine birds, unlike any other seabirds that can also feed on fresh water, like some species of pelicans, for example, or cormorants. But the boobies are occupying most of the planet except Antarctica. They are excellent planche divers. So they get some altitude before falling freely in the water and attaining depths of, I don't know, 2, 4, 5, 6 meters and capturing the pre underwater,.

Scott Taylor: Of course, that's, I mean, it's pretty amazing. They have specialized nostrils too, right?

Carlos Zavalaga: Yes. Actually, if you check the conical, you know, shape of the bill and you don't see the typical, you know, holes, nostrils, other birds have in their bills. They are hidden, pointing a little bit like den warts, but it's just, it's a very thin layer at both sides of the Coleman of the upper bill.

Scott Taylor: Yeah. For anyone who's like jumped into a pool as a kid or the ocean and then Got that nose full of water. Makes sense that boobies would have this adaptation to not have that happen every time they try to get food. So for the boobies specifically, the gannets are this amazing group of bird kind of in the high and low latitudes around Australia and South Africa and then up into the Atlantic Ocean. But for the boobies there's people consider between six and seven species of boobies and three of those, brown, red footed and masked are all around the planet. So they're what we call pan tropical, right?

Carlos Zavalaga: Yeah.

Scott Taylor: And then there's more in the eastern tropical Pacific. That's where you find Peruvian blue footed and Nazca. And given that they're all like living kind of in ocean environments, obviously ocean environments vary a little bit. Do they directly compete for food or are there ways they partition food resources where they have multiple species occurring?

Carlos Zavalaga: Well, some of them are what we biologists call allopatric. They are not mixed in space and time. One way to avoid competition is just by partitioning the space they use. For example, the Nazca boobies in the Galapagos are more traveling long distances, feeding on flying fish mainly. The red footed boobies are intermediate, they are between the pelagic and more incher and the blue footed boobies are more inch or feeder. So the competition is not so extreme. In Peru for example, we have two species of boobies, the Peruvian booby which is endemic of the Humboldt Current, which is, let's say cold water upwelling system. And in the north of Peru we have the blue footed booby. And there is an area where both blue footed and Peruvian boobies breed in the same place. And there, so there may be level of competition, but to avoid that, what is going on is that in this place there is a large population of blue footed boobies and a small population of Peruvian boobies. So Peruvian boobies are more prominent in the south. So in the north when they are competing with the blue footed boobies, they are in smaller numbers. So the competition would be lower if for example, there were more Peruvian boobies in this place. They both feed on anchovies and they feed almost the same way in the same areas. How do we know that? Because we place them in small devices and we know exactly where they're going. So they share the feeding area, but again they avoid competition by reducing one of them, at least reducing their numbers.

Scott Taylor: Right, yeah. Can you talk a little bit about how you figured that out? And I helped a little bit back when I was in Peru to get these GPS loggers on the boobies and also depth loggers on their legs. So can you talk to us a little bit about just what that field work is like and then what the data showed because you were tracking them both on Lobos de Tierra and Lobos da Fuero, which are these islands in northern Peru where I had the pleasure of living for a few weeks with you back in. What is it? It was like almost 20 years ago.

Carlos Zavalaga: 20 Years ago.

Scott Taylor: Crazy. Yeah. Tell us a little bit about tracking them and getting that depth information to really understand like this whether there is or isn't competition between blue footed and Peruvian boobies.

Carlos Zavalaga: Sure. There was like the beginning of my studies with boobies. So my first contact with boobies, I was studying other seabirds before that date or that year. But the movies were like, you know, part of the landscape for me. It's like I was just, you know, working with cormorants and the movies were on the back of the background, you know, in the landscape. So which is watching them just from distance, you know. But in Lobos, one day I was working for an institution here in Peru and my work was to count sea lions on Lobos de Tierra island in northern Peru. So I landed on the island for first time and my first impression was just watching the blue footed movies because they were all over the place who were not scared of humans so you could walk beside them without any problems. And I said, someday I will come back. And it was true. So I met a person in Mexico who was building this small GPS to be used in zippers mainly, and from Italy. His name is Giacomo, who was with us in the. In the. And it was an anecdote, you know, because I was a PhD student in the US and I, you know, was in this meeting and so I met Giacomo and I said, oh, Giacomo, how are you? I said, oh, yeah, I study blue. Well, I would like to study blue footed movies, but I don't have money. And I. And he said, no worries, give me a date and a place to land on Lima and I will go with you. And that was it. So he brought the GPS and he brought everything. He taught me how to use them. For first time, first question we had was, okay, the blue footed boobies are found usually in tropical waters. Right. So in Panama, southern Mexico, et cetera. And what they are doing here in Peru, of course, they are in Lobos de Tierra island, which is in northern Peru, but still under the influence of the Humboldt current.

Scott Taylor: Yeah, the water is still very cold there, right?

Carlos Zavalaga: Yeah, still within the Humboldt Current realm. And my first question was, are they going offshore to tropical waters, you know, outside the Humboldt Current waters. They are feeding on tropical fish species, not anchovies. And this was the first question we had and that was a magnificent opportunity. Opportunity for testing this because the blue footed boobies were actually breeding in a system. So let's do it. And we did it. And we find out that the blue footed boobies were feeding inside the Humboldt Current and feeding on anchovies. So that was very new for us. Very new.

Scott Taylor: Yeah. And so that was before I went. So was Giacomo was with us when I went out. I remember he bought that trumpet in Lima to learn how to play the trumpet out on the island. What a nice guy. But can you talk to everyone about how you figure out what they're eating? Because I was, I helped with this a bit when I was out there too, but it's kind of gross.

Carlos Zavalaga: Yeah.

Scott Taylor: Okay.

Carlos Zavalaga: Okay, that's interesting. Usually when you grab a booby to, you know, attach a GPS logger, for example, you need to grab it. So you use a long pole. Sometimes you can just do it with your hands. Of course you need to use a glove because the bill of any booby organette is very dangerous. They have serrated and they are very sharp. It's very dangerous. Okay. So you need to use gloves, of course. Nazca boobies in the Galapagos, I grab them from the bill, just extend my hand and grab them from the bill without any problems. And if they are returning from a foraging trip, they immediately regurgitate. So you don't need to do anything, it's just the act of grabbing them. Yeah, you know, makes that they can. They regurgitate all the food. So you have all the anchovies, all the fish they feed on during that time, that trip. So we were collecting those and then putting in bags and then because we needed to, you know, grab 10, 12, 15 boobies in a row. So we return it to our station with 15 bags of food, 15 bags.

Scott Taylor: Of booby vomit that you then had to sort through.

Carlos Zavalaga: You know what, they were fresh.

Scott Taylor: Yeah, it's not that gross. I mean, it's not the.

Carlos Zavalaga: Not so smelly, you know.

Scott Taylor: Yeah, I mean it's still oily fish, even though it's fresh. Oily fish. But I'm pretty sure some of the clothes I wore when I was out there had fish stains like for the rest of time until I got rid of it.

Carlos Zavalaga: I can imagine, you know, you coming from genetic lab, you know, very. Everything you know is very Pristine and clean, you know, and coming for first time to a guano island when is everything is the opposite. You know, traveling in fishermen boats, they are not clean at all. You know, working with the boobies and the wano and the ticks and then the vomits. It was very traumatic for you, for sure.

Scott Taylor: It was definitely what I describe now as type two fun. Yeah, I was definitely stressed out a lot of the time. I think it was my first trip outside of, like, North America proper. And then I'm on these guano islands covered in ticks. I remember when we got to Lobos de Tierra, I guess, because we'd been in the boat for 14 or 15 hours at that point, and it was morning. We did the sampling and I went to lay down and I was in that little hut, and I remember feeling like I was being watched and looking over on the pillow and there were like five giant adult ticks just slowly walking towards my head. And I was like, nope, absolutely not. I'm not going to nap.

Carlos Zavalaga: Yeah. Oh, man. Okay.

Scott Taylor: Even just using a rope ladder to get onto some of those islands was, like, the first time I'd ever used a rope ladder. It's hard to paint a picture for people listening, but for some of these islands, like, you have to go up to a dock that was originally built for, like, the guano ships that would collect bags of guano. And like, the rope ladder, I feel in my head it was 35ft, but maybe it wasn't that long, but it was a long rope ladder. Until I get onto that out of a boat that's moving in, you know, the surf, and then climbing up a rope ladder, which, if you're listening, you don't use, like a normal ladder. You have to climb up with the ladder, like, between you. It's hard to describe. But anyways, lots of firsts for me on that trip. Definitely.

Carlos Zavalaga: Yeah. Sorry, Scott.

Scott Taylor: No, don't apologize. I had a great time. I mean, it was definitely character building. And I think fondly about the guard on Lobos de Fuera who would give us mangoes. That was pretty clutch for my mental health.

Carlos Zavalaga: Fresh fish as well.

Scott Taylor: Yeah. I mean, the ceviche was amazing.

Carlos Zavalaga: Yeah. I don't remember until today having so high infestation of ticks. There were millions of them and they were crawling over your body. So we needed to take the blood sample with all the ticks on us, you know, and then we finished. All of us ran to the dock and jumped off the water.

Scott Taylor: Yeah.

Carlos Zavalaga: With all our clothes on.

Scott Taylor: Yeah.

Carlos Zavalaga: I mean, we didn't care. How high was the dock to the water? We didn't care. So we just jumped.

Scott Taylor: No. Yeah, that was probably the highest I've ever jumped into water from. And also the water was very cold. For anyone who sing the Humboldt Current is cold water. It is very refreshing. Almost takes your breath away. But yeah, that's funny that that was like the tickiest it's ever been. I thought that was just like, I mean, I guess lobo stuff wear Tahira weren't as ticky. But for folks listening, seabirds can get a lot of these ectoparasites, right. They're living in these really dense colonies which is a great place for things like ticks and other parasites to live. But yeah, I've never seen that many ticks in my life. And they're different than the ticks that people in North America might be familiar with where we have these hard bodied ticks that you can't really kill. These ticks are soft bodied or gassed ticks and you can squish them which is really satisfying. But when there's 10,000 of them on your arm, you can't squish all of them. Yeah.

Carlos Zavalaga: Particularly when you are focused on taking blood.

Scott Taylor: Yeah, yeah.

Carlos Zavalaga: You cannot move so you need to be very precise and you know all the, you know in your face or everything. So it's, it's. Well that's the way that was the way.

Scott Taylor: Yeah, that's the way we got through it. We found out some cool things about the fact that blue footed and Peruvian boobies hybridize and they have this really interesting population structure and all of that. And yeah, we're even, you know, revisiting all of this work with whole genomes now. And Danny Jackson is leading this cool new paper about booby phylogenomics. So I'm excited for that to come out soon. I think most people probably are more familiar with blue footed boobies because they have these bright blue feet and they do these funny displays. How does the, the appearance and the, the behavior of the Peruvian booby differ?

Carlos Zavalaga: Yeah, this is more like cartoon, you know.

Scott Taylor: That's awesome. I wish I had one of those.

Carlos Zavalaga: But it has the necessary feature to show you what makes the difference between Peruvian booby and blue footed booby. And one of them is the size. The blue footed boobies are slightly larger than Peruvian booby. In average a Peruvian booby can weigh I would say 1300 grams, 1.3 kilograms, whereas an average of the Peruvian booby is 1.6, 1.7. Maybe this is One of the differences, the other one is the sexual dimorphism. In boobies, females are larger than males. So this is something not very common in nature, particularly in birds where the males are usually larger than the females or they are similar. But in boobies the female are larger. Well, in the blue footed booby, the female is much larger than the male than in the Peruvian booby. What it means, it means that when you are in a blue footed colony, just by the size, you can recognize or discriminate between a female and a male. But when you are in a Peruvian booby colony, that's more difficult, it's much harder. Harder. And another characteristic is the color of the iris, the eye. See, it's red wine in the Peruvian booby. Red wine, yeah.

Scott Taylor: Carlos is holding up a little figurine of each of the booby species. If you're listening and not watching. And yeah, the color of Peruvian booby eyes is the color of red wine. A beautiful, really amazing color actually.

Carlos Zavalaga: It's well represented here.

Scott Taylor: It is, yeah.

Carlos Zavalaga: Yeah.

Scott Taylor: That's an awesome sculpture.

Carlos Zavalaga: Whereas the, the blue footed booby is yellow.

Scott Taylor: Yellow, yeah.

Carlos Zavalaga: That's quite different.

Scott Taylor: Yeah. And very satisfying that when they hybridize, the hybrids have orange eyes. The perfect combination.

Carlos Zavalaga: Yeah, it's amazing. Exactly. Yeah, that's amazing. And yeah. And when you are in a blue footed booby colony and also in the Peruvian booby colony, you will, you will hear in the colony the background noise, the boobies and you will hear grunts, but also whistles. So you will hear something like. But also you will hear. So this is because the females grants in both species.

Scott Taylor: Both species.

Carlos Zavalaga: Whereas the males whistle.

Scott Taylor: Yeah.

Carlos Zavalaga: So I think that's the main. There are other differences of course, but I think they are the main ones. Of course. The color of the feet, this is pretty obvious. Right? And movies of course is blue. But they have different tones of blue.

Scott Taylor: Yeah. Depending on their carotenoids. Right. So I guess the color of the eyes is related to carotenoid coloration, which we've talked about on a previous episode as well. Whereas the color of their feet is the same. This cool combination of carotenoids and structural blue.

Carlos Zavalaga: Right, yeah. And it's used as a measure of quality for sexual selection. In this species. The Peruvian boobies, they have a gray, gray feet. And in the hybrid you will find the gray feet, but there are dots of blue.

Scott Taylor: Little blue patches.

Carlos Zavalaga: Yeah, like the perfect hybrid, the blue footed and the Peruvian booby.

Scott Taylor: Yeah, it's exactly what you'd expect if you mix the two Together. And that red coloration of the Peruvian booby's eyes is probably also carotenoids, but ones that have been modified to be red instead of yellow, which is pretty impressive. Yeah, I love them. They're such awesome birds. What has been kind of surprising about them for you or what have you come to realize about like the difficulty of life for a seabird from studying boobies specifically, you know, when, when you.

Carlos Zavalaga: Study them deeply and you find out some special features of them that makes them so different. The blue footed boobies dive deeper than the Peruvian boobies, for example. This is one major difference. And when I studied the Nazca boobies in the Galapagos, I was trying to get records of deaths because I, I thought, okay, this is a bigger booby and they should dive deeper, you know, because if they use the momentum of the fall, the heavier you are, the deeper you will attain in the water of the culling water. So I was tagging Nazca boobies in the Galapagos Islands to find out how they dive. And when I recovered the loggers, I found out that something was wrong. And I thought that the loggers were not working because really, you know, I found for example, 5 dives or 6 dives of less than 1 meter in 13 hour trip while the blue footed boobies can make 50, 70, 100 dives in less than 2 hours or at the most 3 hours. And honestly I thought my loggers were not working at all. But then I found out for first time that one possibility was that they were catching the prey in the air. But by that time I didn't know that, so was not a very common finding. But then having all these pieces like, you know, very few dives, not so deep, very shallow dives and returning with flying fish in their stomachs. So make me think that that would be a possibility then, you know, with the use of, of small video cameras, I'm talking about 15 years later, 20 years later. Yeah, yeah. Was confirmed that in fact they feed on flying fish in the air. So that was the reason why I didn't get too many dives for this large booby, you know. Yeah, yeah. So this is some of the, you know, the differences I found and why I am still working with the movies. There is another reason too. The boobies in Peru played a so important historical role because the movie together.

Scott Taylor: With.

Carlos Zavalaga: One Eye Cormorant and the Peruvian Pelican are guano producers. For those who are not familiar of guano, guano is, you know, it's the dropping of seabirds and here in Peru they accumulate built up in large amounts. I'm talking about tens of thousands of tons accumulated on the surface of the island because we have large numbers of Peruvian boobies, one eyed cormorants and Peruvian pelicans. And the government harvest this guano every five, six years on different islands to be all as an organic fertilizer. And in Peru we have this tradition since the Inca times. So the Inca.

Scott Taylor: Yeah, it's incredible.

Carlos Zavalaga: Yeah. And the bubies and the cormorants were not painted, but they were represented in the walls of the temples of ancient civilizations here in Peru. So Peruvians are very, very familiar. And we are or the coastal population live in close association with the Peruvian boom since historical, ancient times. And this is why, from my point of view, it's so important to study them because they still play an important role in the ecosystem, provide services like guano, for example. But now or today they are suffering the consequences of different pressures like avian flu, recurrent and more frequent El Nino pollution, invasive species on the island, rats, cats, et cetera. So the populations are decreasing. So now I, I'm very interested to know how to solve all these problems.

Scott Taylor: Yeah, history is amazing. Like the history of the guano industry and how much money was made off of poop from birds. Like, for folks listening, it's hard to overstate the importance of the guano industry to Peru as a country historically, I mean, and contemporarily back before we had the ability to make ammonium, basically before the Haber Bosch process was discovered, natural bird guano in places like Peru and then just a few places in the United States was this really important source of nitrogen for both fertilizer and gunpowder production. And so the Humboldt current is this, we've alluded to it. It's for me, it's the most impressive marine ecosystem I've ever witnessed. It's like the richest, most full of life place, you know. Could you walk us through what happens when there's a really strong El Nino? So when you have warm water instead of cold water, what does that do to the birds? And you just alluded to the fact that these El Nino events are becoming more frequent and more intense. So what impact is that having on, on Peruvian boobies?

Carlos Zavalaga: I think the sea surface temperature increase is the most notorious. Why? Because the anchovy, which is the main, you know, or the keystone prey in the whole ecosystem, is they don't like warm water, they live in cold water and when El Nino arrives, they disperse to cold water or they are Going deeper in the water. So they are far away from their predators, including boobies, cormorants, penguins, whatever the consequence is. This is a severe drop of the population number. So very severe. Severe. So from millions to maybe hundred thousands. Okay.

Scott Taylor: Wow.

Carlos Zavalaga: And after El Nino, usually in the past, you have a period of time for the population to recover before the next El Nino arrives. In the last 20 years, for example, we have witnessed at least 12 El Nino between years. 12.

Scott Taylor: That's more than historical.

Carlos Zavalaga: Yeah, of course. And this year we have another one.

Scott Taylor: This year is going to be a big one, right? Yeah.

Carlos Zavalaga: And we had one big one two years ago, so. So the birds are trying, of course, of do their or follow their instincts. Right. They don't think that El Nino is coming. They just found the conditions breeding as crazy and trying to recover, you know, have this pattern and still have more anthropogenic pressure, like, for example, overfishing, avian influenza, pollution, et cetera, et cetera, et cetera. This, you know, pattern is still more sharp.

Scott Taylor: Yeah, that downward trend will continue. And we did talk about on a previous episode of the podcast Avian flu, which has hit Peruvian boobies pretty hard in Peru, along with other seabird species along the coast of Peru. They've experienced pretty strong declines because of avian flu. And then again, the anchovy fishery off the coast of Peru is incredibly important economically, and it's in direct competition with the birds for the food that they need for their chicks. So, yeah, there's a lot more anthropogenic stressors on that species now than there were historically. We've reached the part of the show that 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. So, Carlos, what do you want to.

Carlos Zavalaga: Call BS on Some people think that boobies are incubating their eggs with their bellies, but actually what they do is use their feet.

Scott Taylor: Really?

Carlos Zavalaga: Yeah. To heat their eggs during incubation. So if you have the chance to check a booby nest with eggs, and you will see that they are protected by the webs of the feet very carefully over the eggs to transfer the heat from the body to the eggs. This is why the feet of the webs and feet of the boobies are very, very full with arteries, and that's because they use them for heat transfer to the eggs.

Scott Taylor: That makes total sense. I hadn't thought about that. And I've even seen these birds in the wild, but a lot of birds develop what we call a brood patch where they lose their feathers and then they have gross looking really heavily. Yeah. Wrinkled skin that they put on their eggs to keep them warm. But if you're a seabird diving into cold water, that would be really bad to have a huge exposed part of your belly. So very cool that they use their their feet to incubate. That's awesome. I really appreciate you joining us today to talk about boobies, Carlos. I look back on our time in fondly and I tell those stories to a lot of folks. So it's fun to revisit them and also get to chat more about boobies and how cool they are. So thanks for joining us today on the podcast.

Carlos Zavalaga: Thank you. A pleasure to talk about boobies and be here to your audience too. Thank you.

Scott Taylor: Awesome. Birds are dinosaurs and around here we like our snacks. So we end each episode with a dinosaur nugget. Today's nugget is There are around 10 species of boobies and gannets, and at least one of them lives in nearly every ocean on earth except the waters around Antarctica. They get their name from the Spanish word for bobo because sailors saw them being clumsy on land and didn't bother to watch what they did in the water. The next time someone calls a booby a dummy, you can let them know they're insulting one of the most impressive hunters in the entire bird family tree. That's a wrap on this week's episode: Okay, but... boobies! What other okay, but birds questions do you have? Leave us a comment and let us know. And leave a rating or like, while you're down there, we'll catch you next time. Bye. Okay, But... Birds is hosted by Scott Taylor, with production and creative by Zach Karl.

This transcript was generated using AI-assisted transcription and may contain errors or omissions. Please refer to the audio or video episode for the most accurate representation.