S4EB - Bat Communication with Gloriana Chaverri

Claudia talks to conservationist and ecologist Gloriana Chaverri about the numerous and diverse ways in which bats communicate. This bonus episode deviates from the usual focus on concepts to a more sustained focus on this large order of animals 

Date Recorded: 29 March 2022

Gloriana Chaverri is an Associate Professor at the Golfito campus of the University of Costa Rica. She is also a Research Associate at the Smithsonian Tropical Research Institute. Her research with bats first focused on the topic of mating systems and social organization, and her past and current projects have a broad focus on the ecology, behavior and conservation of bats. However, Gloriana’s main interests is currently on bat vocal communication, a topic that she has been developing since 2009. Connect with Gloriana on Twitter (@morceglo) and learn more about her work on her website (www.batcr.com). 

Claudia (Towne) Hirtenfelder is the founder and host of The Animal Turn. She is a PhD Candidate in Geography and Planning at Queen’s University and is currently undertaking her own research project looking at the geographical and historical relationships between animals (specifically cows) and cities. She was recently awarded the AASA Award for Popular Communication for her work on the podcast. Contact Claudia via email (info@theanimalturnpodcast.com) or follow her on Twitter (@ClaudiaFTowne).

Featured: 

Social communication in bats by Gloriana Chaverri, Leonardo Ancillotto, and Danilo Russo; Social calls used by a leaf-roosting bat to signal location by Gloriana Chaverri, Erin H. Gillam and Maarten J. Vonhof; A short history of nearly everything by Bill Bryson; bat sound recordings made by Richard Ranft from the

A.P.P.L.E
Animals in Politics, Law, and Ethics researches how we live in interspecies societies and polities.

Sonic Arts of Place Laboratory (SAPLab)
The SAP Lab provides workspace and equipment for students engaged in sound related activities.

Sonic Arts Studio
The Queen’s Sonic Arts Studio (formerly Electroacoustic Music Studio) was founded in 1970.

iROAR Network
iROAR brings together podcasts that aim is to make the world a better place for animals.

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Transcript

SPEAKER_00: 0:00

This is another iRaw podcast.

SPEAKER_02: 0:04

So there's also a possibility, a possi a big possibility that a collocation may be also used not only for auto communication but for social communication.

SPEAKER_01: 0:23

Welcome back to the Animal Turn, everyone. This is season four where we're focused in on animals and sound. And you will be forgiven for being a little bit confused because, as you know, normally episode 10 of every season is focused on a grad review. But instead of having a grad review, this episode is looking at back communication. So I ended up in probably what's a really nice and delightful predicament in that I had sent out an invite to one guest, and while waiting, I'd waited for a bit of time and thought that they weren't available. And then I sent out an invite to another guest, and then both guests kind of said yes to me at uh within two days of one another. So instead of turning away someone who had put aside time to talk about animals, I thought, well, why not give you a bonus episode? In the last episode, we spoke about dolphins and we, you know, we touched a little bit on echolocation and we thought about how differently they experience the world. And I think you get a taste of that here in this episode. So instead of focusing on a concept, which is normally what we do in every episode, in this episode I'm really just focusing in on bat communication. And myself and Gloriana speak throughout the whole episode just talking about bats. And you can hear that I know nothing about bats, and I'm trying desperately to understand the ways in which they're categorized and the numerous ways in which they experience the world. And I hope that you find it as illuminating as well. So let me tell you a little bit about Gloriana. Gloriana Shaveri is an associate professor at the Golfito campus of the University of Costa Rica. She's also a research associate at the Smithsonian Tropical Research Institute, and her research focuses in on bats. It was first focused on the topic of mating systems and social organization, and both her past and current projects kind of have a broad focus and interest in ecology, behavior, and the conservation of bats. However, her main research interest currently is on bat vocal communication, a topic that she's been developing since 2009, and which we spend a great deal talking about in this episode. We don't only speak about the ways in which bats experience the world through sound, but the numerous ways in which bats communicate. And it's just a really delightful conversation where I learn a great deal, and Gloriana is just so generous in giving. So I hope you enjoy listening. Hi Gloriana, welcome to the Animal Tone Podcast.

SPEAKER_02: 2:42

Hi Claudia. Very nice to be here. Thank you for the invitation.

SPEAKER_01: 2:46

So today we're going to do something slightly different to what the normal episodes are. So normally in an episode I center a conversation on a specific concept. But today, because the whole season has been looking at sound, uh I thought it would be really cool to actually center on a specific animal. Now there have been some animals that have come up in previous episodes, of course. In the previous episode, I spoke to Denise Hertzing and we spoke about dolphins for a long time. I've spoken to some folks about chickens and some of the sounds they make, and we've we've definitely spoken about a variety of different animals. But I thought it would be really cool to just maybe speak to you about bats and bat communication today because I don't know. I honestly I started reading a little bit about bats and I realized just how little I knew, so I thought it would just be fun to talk to you. So thank you so much for joining me today. Before we get into the conversation about bats, though, I'd like to learn a little bit more about you. So could you maybe tell us who you are, what kind and what kind of work you do?

SPEAKER_02: 3:46

The work that I focus in has always been on bad social behavior, um, how individuals locate each other, why they stay together, and for example, how big the groups are, how stable uh they are as well, if individuals are staying all the time together or they're splitting up day after day. And so the the topic of uh social behavior in general is what I was always interested in. But now lately, of course, I've been focusing quite strongly on the topic of communication uh as it is related to you know to this topic of social behavior as well in bats. Um, and so my my latest and the work that I do the most is uh focused on yeah, how bats in particular use vocal communication for these social tasks. And yeah, I'm I'm uh Costa Rican. I was born in San Jose, uh the capital, um, and I came to live in a small town called Colfito, which is in the southwestern part of the country. Uh, and it has some of the best areas for for studying animals, very you know, some huge protected areas, very pristine, and so the work here is just idyllic, I think.

SPEAKER_01: 5:15

Amazing. Uh it sounds, I mean, for the type of work you're doing, it sounds like you're in exactly the right the right place to be uh asking the questions you are. Uh, I love that you were foregrounding social communication. So, you know, when I when I spoke to Denise Hertzing, we spoke a lot about I think about the natural sciences and kind of how observation works. Was your journey to understanding bats one through kind of ethology and ecology, or did you start in the social sciences and thinking about uh you know bat communication?

SPEAKER_02: 5:48

Um, I think I mostly started with a stronger ecology background, I think. So, for example, I was always interested in you know how the environment affects bats and uh more like the typical questions that many of us ask at the beginning has uh a strong ecological and conservation focus, like which type of habitats are harboring the the best quality of or you know the best bad communities, and from there, you know, how those those differences in those communities or habitats may be affecting you know social behavior in in particular. That's more or less the transition I made. So from being interested in something that's a bit more general, ecology and conservation, then some of the questions pertaining to more you know social behavior or animal behavior in general, uh started pouring out after I learned a bit more about the ecology and conservation of bats. So it was more, yeah, I think it's it was a transition from mainly ecology towards animal behavior, which is something also that I I always wanted to do of since the beginning.

SPEAKER_01: 7:05

Fascinating. So you were asking uh ecological questions and then in kind of asking ecological questions, did bats then emerge as a you know a really important species or or group to understand? Or did you kind of start with a really keen interest in bats but asking ecological questions about bats?

SPEAKER_02: 7:25

I started mostly with an interest in bats.

SPEAKER_01: 7:28

Uh-huh.

SPEAKER_02: 7:29

Although before I started working with bats, I was interested in mammals and social behavior in general. But then when I started learning about bats, uh, then I had so many basic questions about uh this large group of mammals that I needed to go to the more basic questions in order to understand some of the others that I was most interested in, like communication and social behavior. But yeah, my my interest is basically started with bats and then then I moved on to some of the topics that I I found most fascinating.

SPEAKER_01: 8:06

And what what sparked this initial interest in in bats? Uh what was it about bats that just made you think, wow, I I really need to understand and learn more about these mammals in particular?

SPEAKER_02: 8:16

Well, I think uh a topic that would come up very often, and this is something that happened to me at the beginning, and that's why I fell in love with bats, is that there's so little known about them. There's such they're a huge group of mammals, uh very diverse in many, many senses. Um, but then there's so little known about them, and uh a lot of people don't like them. So, in a way, it was like this huge group of mammals, very interesting, and a lot of people don't like them. And so it was it was very fascinating to me. Why why people don't like them, how to understand them better and make people fall in love, as many of us do. That was, I think, a big, big way to uh to start my work with bats.

SPEAKER_01: 9:05

I'm happy you said that because obviously, in doing a season on animals and sound, you start to think about the variety of ways that animals experience sound. And you know, dolphins and bats are kind of I think characterized, they often come forward when thinking about sound because they have this kind of unique relationship with sound because of echolocation. But when I came across your paper uh and I started reading, I was just I was something like I was blown away, really, because one, I had no idea that bat the bat group was so huge. Really, like I thought bats were just kind of out there, these small little, and then you start to unpack the variety of ways in which bats communicate. And I think we we tend to foreground echolocation as being like, oh, how do bats communicate? They communicate with echolocation. And we've got this really simple story about bats. Uh, and I think that's why I really wanted to talk to you today is to just pry apart some of the complexity of how uh what we know about bats, but also what you think this could tell us about how bats experience the world. Um, so maybe we could start with talking about the size of this this group. When you say it's a big group, what are you what are you actually meaning? What does that mean?

SPEAKER_02: 10:20

Well, um for all of you know this the mammalian group, uh, which is of course to us an extremely important group of organisms in this planet, um the most diverse uh order of mammals are rodents. So we have rodents, there's thousands of pieces of species, and the second one, which is still also highly diverse, is the order of bats, uh which is called Chiroptera. And so it's we're talking about uh, let's say around 1,400, 1,500 species. There's a lot of new species that are being still discovered uh on a yearly basis, basically. So this is a large group, and you know, it's the only group of mammals that can fly, and so that that increases the complexity and the and how interesting this this group of mammals is.

SPEAKER_01: 11:19

We're going back to I think primary school now and thinking, because it's it's crazy. Like, yes, I'm a PhD candidate, but it's I I tend to take a lot of these kind of categories for granted, right? We speak about species, we speak about orders. Um, and then I realize that the more I look at it, the more I'm like, what defines a species or what defines a mammal, the more I try to define it, the the the harder it almost somehow, for me at least it seems to be like what constitutes a species. So when you're speaking here about an order, if I understand correctly, and please help me here because I'm not an ecologist, you've got you've kind of got you've got the animals, right? You've got animalia, and then underneath animalia, you've got mammalia, which is the big group that we belong to, and then I think there are other groups like insects and fish, and um uh and then under that, under mammalia, we've got orders. So the orders are like the next big category. Uh, and now you're saying that rodents are the first, the biggest, and then you've got um bats, which what was the word you used? You used chlora chiroprachi. Chiroptera. That sounds like a it sounds like a dinosaur, chiroptera. Okay, and then in there you've got bats, and bats are really dynamic and diverse. And then something you you mentioned in the paper as well, which I didn't know, is just the size difference in these bats, right? So you've got ones that are about the size of what, a penny tiny, and then you've got, are they called flying foxes, the really large ones in is it Australia?

SPEAKER_02: 12:57

Yeah, there's in Australia, Africa, yep, the old world, all you know, paleotropics basically.

SPEAKER_01: 13:04

So could you maybe tell us a little bit more about some of these different kinds of um variances? So they've got difference in size, but maybe if you could highlight some of the other variances when we think about um bats, because we've kind of got a stereotypical idea of bats. So uh if if I could just give you an opportunity now to kind of maybe bring more color to what our imaginations are with regards to bats.

SPEAKER_02: 13:26

Definitely the the difference in size is something that's very interesting. The smallest is let's say two, three grams, it's something so, so small. It's called the bumblebee bat. Um, and then the biggest is I don't know, one kilogram, which is huge for a flying organism. Uh, and so the wingspan is enormous, and oh, it's it's so fascinating. And so this is only about size. Let's think about, for example, what they eat. Uh, so they can eat the majority of species uh are insect eaters. Um, this is such an important resource for the majority of species, especially those that live uh in areas, temperate regions where fruits are not that common, or flowers, for example. And so insects is the main diet for the majority of species. But then we have those that are eating fruits. So the the really big ones that we're talking about, uh the flying foxes, for example, they they also specialize in eating fruits. So they can carry these big mangoes or other fruits that they feed upon. Um many other species also have very interesting specializations, like very long snouts, extremely long uh tongues, so they can use to reach the the nectar from flowers, uh, you know, with various uh forms. Um we also have uh you know a very interesting group of which is very diverse, like it evolved in different groups of bats, uh, which is the ones that feed on fish. So we have the fish eating bats, they have you know fascinating specializations or adaptations to be able to fish or you know get the fish. So they they fly very close to the water, like they they're just barely on top of the water, and when they detect a movement with their collocation, uh so they they stick their feet inside the water and they have very long uh toes, and the nails are also very long, and they grab the the fish very efficiently. Wow. And so there's several species that that do this fish eating. Um there's also the ones that you know the carnivorous bats, um like they they hunt, you know, other other bats, uh birds, um, and including also one really fascinating species that has been studied for a long time, uh, is the frog-eating bat, uh Tracopsirrosus. And they they take advantage of the sounds that are emitted by the male frogs when they're you know uh searching for their mates or trying to attract their mates. And so they take advantage of those calls and they locate them and they they eat them. Um and then of course we have the the really famous or infamous, I don't know, the the vampire bats, uh, which is an extremely fascinating group uh of bats that feed exclusively on the blood of birds mostly, but also one species also feeds on the blood of mammals. Um, so this is also an extremely interesting specialization, which just shows some of the diversity of you know that that has can be found in bats.

SPEAKER_01: 17:05

That's incredible.

SPEAKER_02: 17:06

Like, okay, so we have the differences in sizes, differences in diet, but we also have differences in in shapes and forms in the face or the rostrum structures that allow them to innovate more efficiently, or these weird shapes that we really don't don't understand well uh what they can be used for. Um and the the diversity of colors, there's some that are orange, uh some are completely black, and we have the white ones. Oh no, it's this I could talk for hours and hours about the diversity of this is only the things that you that you can see and uh very easy, but then you know the diversity in communication, in social behavior, ah, you know, it's enormous.

SPEAKER_01: 17:59

I can hear your passion. It's just it's just coming through. And and I mean, just in off the top of your head, you've rattled off more about bats than I than I ever knew. Uh in terms of geography, so there's uh in my rudimentary understanding, I'm assuming that these differences emerge from different environments, right? Because they've been in relationship with different environments and different species. So, like you spoke about the frog there using sound to um, I mean, the the bat using the frog sound as an effective way to both hunt but also to interact with the world. So I'm guessing here, based on just the diversity of bats that you're speaking of, we also find bats in numerous places.

SPEAKER_02: 18:39

Bats are the mammals that have the widest distribution in the world. So, for example, in many islands, there are no native mammals except for bats. Yeah, definitely their distribution is it's worldwide, it's the most widely distributed group of mammals.

SPEAKER_01: 18:58

So I suppose it makes sense.

unknown: 19:03

Exactly.

SPEAKER_01: 19:04

Yeah, yeah, yeah.

SPEAKER_02: 19:04

Exactly.

SPEAKER_01: 19:05

That's it. Wow, and I mean it's just it's it's fascinating because I think for for me at least, they've so often been invisible. I don't see bats, they're not really so. Yes, I grew up in South Africa and and I was exposed to a variety of different mammals. Uh, you know, and then coming to North America, where there's a very different kind of experience with with mammals, you know, like urban animals, like squirrels and stuff, I didn't see in Johannesburg. But um, but bats, I know that they're there, but I rarely ever see them. Maybe at dusk, in all of these places, I'll sometimes see what seems to be a movement in the sky, but they don't kind of demand attention in the way that other animals do that we live with. So is is that are all bats uh nocturnal? Is that is that why we don't really see or recognize them?

SPEAKER_02: 19:53

I well, it I think it's the majority of species are nocturnal. Uh there are some that are diurnal, but um definitely the the wide majority, for example, all the ones that we have in in America, uh the continent is they're they're all nocturnal. I've seen some species, definitely they're active during the day. The ones that I've been able to see, like in other parts of the world, but definitely the majority of nocturnal. So that really plays a big role in our understanding and appreciation of bats, I think. It's just uh the fact that they're so mysterious, according to a lot of people. We don't know what they're doing, um, and they only come out at at night, and they're also dull colored, and I don't know, it's just it casts like this mysterious aura around around bats that I think has created a more negative impression of them.

SPEAKER_01: 20:49

And and I think it's it's also there is this interesting relationship between visibility and animals that we take seriously. So uh when I spoke to Jonathan Bulcom about fish, for example, he said one of the reasons why he thinks fish are so um you know overused and why f the welfare of fish is not necessarily taken seriously is because they're in a different medium to us. We don't see them kind of in in the way, so they're not even of the same the same order as us. So kind of finding empathy for uh beings that are in a completely different world is really hard. And I think to some extent it's like that with bats, uh, but instead of the water being kind of the separation, it's it's it's our rhythms, it's our daylight versus nighttime. It's uh and I think that that's really interesting to think through that we we're living with animals that are all around us that we don't see, uh, but that's not a reason to vilify them.

SPEAKER_02: 21:43

That's true. Yeah, that's a good point. And yeah, the fact that we cannot see them or you know, we never interact with them also doesn't create this empathy that I think people have towards birds or other mammals, I don't know, squirrels or monkeys that you can see during the day. So that's that's an excellent point, definitely.

SPEAKER_01: 22:04

So maybe we could switch now to talking a bit about the communication aspect, which is is your passion. So we've spoken a lot, I think, about the physiology and and stuff. But something that I've kind of in starting this podcast that I've been learning now increasingly is that animals communicate in such diverse ways, learning that whales have different dialects and uh and some whales don't necessarily understand what other whales are saying, or chickens have a variety of um words and ways of communicating with the world. And I had no idea. So could you tell us about how bats communicate and and maybe which bats you're focusing on here and some of the ways in which they communicate?

SPEAKER_02: 22:51

Um just to begin, I think it's really important that you know, for animals in general, but bats in particular, we have so little information about how they really communicate. So there's we're the information is growing and growing uh steadily throughout the years. So, but there's still so many things that we don't understand quite well about them. We know that uh olfaction smell is really important for bats, uh that they may may be using some odors to communicate certain aspects of their lives, uh, whether they're like in many other mammals, uh, whether they're they're in estrus. For example, if females are already available for copulating or they can they can start mating. Um they also have many different glands that uh they they emit these interesting odors. We also don't know a lot about them, but still there's there's a few groups that are working on this issue quite a lot. So I think that's that's also very interesting, and it's there's a lot of room for growth here. Another topic that I think is fascinating, and no one has really done much about it, is like visual communication. Are bats really using some of their markings or postures or something to communicate with other individuals? Even though they're nocturnal, they're you know sometimes when they're at their roost, they're resting during the day, um, they're still visible to each other. So we we still don't know if they may be able to communicate visually, for example. And definitely one of the main forms in which uh, or at least that we have been studying is vocal communication. So we know that you know, bats, uh, you know, a lot of the species are nocturnal, so visual communication is very complicated and they'll also move in very wide areas. So, of course, olfaction and smells might not be really useful in you know when they use they're using such large areas. So acoustic communication definitely is the way that we think may be most important for bats for communication. So you're right in saying that the the majority of people has focused on what's called this auto-communication, which is echolocation. So they're producing sounds uh with the aim of those sounds returning some information uh you know about their environment, the availability of resources. Uh, so it is uh an important way in which they auto-communicate. Um but and there's also some some evidence that other individuals may be using these uh echolocation sounds to gather information about the the individual that that's emitting the echolocation. So there's also a possibility, a possible big possibility that echolocation may be also used not only for auto communication but for social communication. Uh so for example, they may distinguish between males and females or individuals that are familiar or non-familiar, and even there they they may be also you know perceiving the the using the information that's emitting through echolocation to, for example, understand if there's a huge availability of resources in an area because they can hear all the other baths that are echolocating and they're uh giving out this information that there's, for example, food that's available in a specific area. And so I think in general, echolocation is has a lot of potential for social communication, but then of course, there are so many uh calls, specific calls that are used for for social communication specifically, uh, and this is the area that I've been focusing mostly on. Like with many other species of birds and mammals, we know that bats emit many different calls in different contexts. And and we know that for some species there may also be dialects. Um, so you know, one population may differ in the way they emit a specific call from another population far away. But there's still so much to learn. For the majority of species, we have no idea which calls they're producing. Um, the the context in which they're producing them is so difficult to understand because we need to see which individual is producing the call, what they're doing at that specific moment, and when that individual produces a call, what reaction do the other individuals have? We really don't know that well. Uh again, this is a topic that's developing quite a lot.

SPEAKER_01: 28:02

And I guess what makes that quite hard, what makes that quite hard is one, you're dealing with because your your work is primarily, if I understand, um your work is primarily in the field. You you go and you watch uh bats, and I'm assuming doing that at nighttime is hard. Um but also bats tend to roost in fairly large populations. Um, so I think we've got a bit of a bias, maybe as researchers, when it comes to understanding animals, to choose to understand and mammals in particular. We we we we tend to think of herds as like single blocks, you know, like if you're looking at a herd of gazelle or wildebeest or something, I think we really struggle to view them as individuals, to say, oh, there's one, there is one buck amongst all of those buck who's experiencing the world in a particular way. Um, yet when we encounter maybe uh some mountain gorillas, they they're a population, but they're a much smaller population. And I think this speaks to some of the ways and challenges of how we know, right? Like it's easier to I think look at a group of individuals, uh gorillas, and and start to discern their relationships. But because it's so hard to understand how these big groups relate to one another, um we tend to just treat them as this single group that don't have any sort of individual significance. Um, are you finding that in in understanding this communication that you're starting to see some social dynamics like I don't know, friendship or uh preferences for who bats hang out with? Are you are you seeing those kinds of variances?

SPEAKER_02: 29:37

Yeah, definitely. And not only my studies, but there are several studies that have shown that like individuals are you know, they prefer to hang out with other, you know, or specific group members, for example. Um that's that's definitely the the case. And in although many species we we tend to think of them living in. These huge groups, uh, for example, the ones that are in caves, the interesting thing is that they still show preferences for uh roosting or being very close to specific individuals. So that's sort of like the first clue. But also often when they move from one roost to the other, they also prefer to move with other individuals. And this is in the case of species that are living in you know these large roosts or these sites that allow the aggregation of many different individuals. But in the case of the species that I work with, uh, the spices disc wing that, um, they live in very small groups. So there's like you know, an average of five individuals. So, and the interesting thing about these species is that they also, when they move, they move together. So they're like their friendship is really, really strong. And this is um, you know, one of those few species that have this really strong connection with their other group members, and this connection may last for several years.

SPEAKER_01: 31:14

So this is also something important to so it's like a pack, it's like how we would think of wolves as a as a pack that that have social reliance on one another. Do you find that in in looking at a smaller group like this, do you find that like different bats are helping other bats care for their young and help? Like, is there that kind of um because it is, I think it is, it does make it easier to kind of look at the smaller group and kind of understand that. So, what kind of social relationships have you started to identify from this close-knit relationship?

SPEAKER_02: 31:51

There is that definitely, you know, moms are taking care of their pups, um, and we're seeing it's still very preliminary because we haven't been able to track individuals for a very long time until now. But we are definitely seeing this. The strongest association typically is the mother with the pup. Um, and so even in some cases, when the group gets very large, uh it seems like the mom is uh is dispersing, it's going away from the group, separating from the group. Uh, and when she does that, she often takes her what we call the young of the year. So the individual that was born that year and it's already flying, it seems like the mother, because the mom needs to get away from that group, which is already very large, but she's doing it with it with her pup. So that's definitely uh a very important and very interesting phenomenon uh that we're we're trying to understand a bit better. But then in the the the whole interactions, for example, within the roost and when they're uh foraging, we still don't understand them that well, which which individuals are showing preference towards each other. And this is something that we're trying to address in a communication sense uh with the project that we have right now. And we're trying to see, for example, when individuals are engaging in this communication or this exchange of sounds, which is very important for the species that I study, um we're trying to see if individuals are responding uh preferentially to others that are highly genetically related to them, or if they prefer to answer to individuals that they know very well, that they're very familiar with. So we think there are there are preferences in these interactions between individuals, but at least for the species that I work with, we don't know that very well. Um, and in other species, this is something that's not highly studied.

SPEAKER_01: 34:00

How how do you how do you do this in the field? So you spoke about some of the challenges. Like what does a day for you look like actually in the field? How how does this all play out? How do you learn this stuff?

SPEAKER_02: 34:11

This is interesting because you also mentioned that you know working at night and all that, but we actually work during the day. So the all these these interactions, these vocal interactions that I've been telling you about also happen very often during the day. Um the species that I work with, they they use this uh very ephemeral resource. The the roots that they use is like when the leaves of plants such as heliconias, when they they start developing, they form this tube, and so the bats go into that tube and they they spend their day there. But they sometimes they get scared because there's an animal that hits the tube or the leaf opens up, and so they have to find uh a new place to roost very quickly. And so this is and this happens during the day, and if it happens during the day, they they're in a big hurry to find a new roost because they may be eaten by diurnal predators, and so and so they hurry a lot to find uh this new roost, and when they're doing that, they're communicating with each other and you know coordinating with each other so they can find the roost together. So for us, a normal day work day would look like we go out, uh we search for these tubular leaves that are developing, and if one of these tubes has a group of bats, then we'll you know capture them very carefully, uh, put them in a in a bag all together, the group together, and then we'll bring them to the lab or to our flight cage. Also, we have this portable flight cage, uh, and we break them there and we start doing whatever experiment we're we're trying out that day. So we work with the bats a little bit, we take very good care of them, we never let them fly for more than five minutes, we always feed them at the end of the experiments, and then when we're done uh for the day, we just go go out again to the field and put them back in the roost where we found them. So that's uh our typical day.

SPEAKER_01: 36:26

Do the bats find this stressful? Do you get um do you get the sense uh that they they find this whole experience quite stressful?

SPEAKER_02: 36:33

When they haven't done it, they they they seem more stressed. Like they vocalize very often and they seem just angry and distressed. Uh and so we take good care because they, of course, this process of being angry and vocalizing that that you know they they takes a lot of energy from them. So we that's why we need to feed them and provide water and everything, just to make sure that they're healthy when they're when we return them. But the ones that we have been I I'm pretty sure we have recaptured some individuals maybe hundreds of times. Um, and so they seem very calm, we bring them to the lab. They're just it seems like they're ready to do their their thing, and then at the end they're they're very anxious to get their their mealworms and their food at the end. And um no, they they do pretty well, and you know, we haven't had like deaths or anything uh that that's very often related to to stress. So I think they they cope well.

SPEAKER_01: 37:37

Why do you think I mean I guess we we could start any sort of research from saying that there's been something of an animal turn, I think, and an appreciation that animals do communicate and they do have culture and uh and and I think in general there's a shift towards starting there, appreciating that and saying that yes, let's start with that as an assumption. Um so why then if if if we're starting from that baseline, why then does it become important to still do these kinds of um studies with understanding back communication? Uh what's the I guess like what's what's the what's the end goal? What's the point? Why is this knowledge important? Uh is it just so that we know or is there more to it?

SPEAKER_02: 38:25

I think there's definitely more to it. I mean, not only are we doing a lot of these studies just for curiosity, right? Um I think this is just a scientific endeavor in general. But then also, uh for example, in many other species, many other organisms, we know that individuals need to communicate for uh for finding mates or for providing sustenance to their young, uh, which obviously are very important fitness-related um activities. Uh, and when they cannot communicate properly, then they may not be able to find mates, they may not be able to provide or find their pups, for example. And so understanding when they communicate, how they communicate, may allow us to also understand how we humans are affecting this process of communication. For example, you know, we know that we're producing a lot of sounds that are masking or even causing stress to animals. And so because we're doing this, they may they may need to change some of their the sounds that they're producing, or they may not be able to find each other. So I think it's important definitely for a lot of conservation-related issues that we need to understand, not only communication, but many other social behaviors as well.

SPEAKER_01: 39:55

I'm I'm happy you brought us back to sound there, because earlier on when you were speaking about echolocation, I think you're you're right. I think bats, unlike many of the other species I've spoken about in the season so far, most people say, oh, we don't really know how they experience the world in terms of sound. We've tended to privilege, I think, the visual or but with bats, we've privileged sound. And but still, I find echolocation and this idea that you're seeing the world through sound, um, remarkable. Like I just think it's absolutely because I I struggle to think about what that must be like. I I think that's my inclination, is um, I try to imagine what it would be like to see the world through sound, um, which is just a remarkable thing to think of. So, yeah, I don't know where I'm going with that. Um, but just in terms of thinking of sound, and you were speaking, so there's echolocation, which you've spoken about, and then there is these response, uh, these inquiry and response calls, which you said happen in the roost, and that you're figuring out what the social communication is. So, in general, we've tended to think of echolocation as a hunting device, but your work is starting to say, well, hang on, more social work might be going on there than just hunting. Um, I know you gave me an inquiry and response clip to play. Could I could you tell us what's going on here and then I can maybe play it for the listeners?

SPEAKER_02: 41:23

Sure. So for the the species that I that I have been working with, um, and this the this this queen bat, when they're in the process of trying to locate a new roost, um so they're flying more or less like a group, and one of the individuals finds uh a place to settle down, uh, a new roost. Um, and so when the individuals are flying, they're staying together, and we think that we're they're using this inquiry, inquiry calls very often just to know when each one of where each one of them are. Um and then one of them finds a roost, and if the one inside hears one of these inquiry calls, then it will start producing the response calls. So they they start vocalizing and vocalizing with these response calls, and then the rest of the groups, the group knows where to find uh that other individual that already found a new place to be, and so they enter the roost very quickly. So it's like in the I know there's that there's this game called Marco Polo, um, and it's this game where there's yeah people in the swimming pool and one of them closes the eyes and starts saying marco and the other responds polo. And so this is the way to find each other. That's more or less what the bats are doing.

SPEAKER_01: 42:48

And there's a different call happening when one of them has found an appropriate roost.

SPEAKER_02: 42:53

Yeah, when they find an appropriate roost, that's when they start producing the response calls. But they they only produce the response once they hear an inquiry call from the ones that are flying. So it's important this that they they never respond if they don't have the inquiry call from the ones that are flying around.

SPEAKER_01: 43:14

So so just so that I understand correctly, um you've got these leaves that are shaped like bulbs, and inside each of these leaves you have small groups of individuals. Uh, and now is it that there are in this specific area there are numerous or several sets of uh bats in different leaves, and one set of leaves gets disrupted by an animal, and those that small group disperses and they send out inquiries saying, Hey guys, we need a place to stay, we need a place to stay. And someone else in another leaf says, Come here, you can stay with us. Is that what's going on?

SPEAKER_02: 43:53

More or less. So the interesting thing is that they basically never or very rarely will join another group. So each one of these small groups, they have more or less their territories. So they have an area that they normally use and where they can find these tubular leaves, right? And so if they get disturbed, the entire group will start flying more or less together, but one individual within that group will find a new place. I don't know, maybe there's some more exploratory, or it's just it just knows better what it's doing. And then boop, they will this individual will go very quickly in that in that leaf, and then the rest will follow once it starts producing the the response. Okay. So this is what's interesting, and it's it's it's one of the ideas we're developing.

SPEAKER_01: 44:50

So it's like going on a treasure hunt, and uh we're all looking for a treasure, and we're saying, Can you see it? No, can you see it? No, and then eventually someone sees it and they're like, I found it, and everyone hops in the same leaf. Okay, all right. Um, I'm gonna play play the calls now quickly. So this is the inquiry. So this is them this they've been disturbed, and this is them, you said, checking in with one another and saying, like, okay, so is that one bat releasing one call?

SPEAKER_02: 45:21

Exactly. And um, just to to clarify, so the what I did is because the calls are very high frequency, this is something that's very important to understand about vocal communication in bats. The majority of the calls that bats are emitting, whether they are echolocation for you know this auto communication or if it's social communication, in most cases the calls are not audible to us, they're ultrasound, very high frequencies. So, for this uh inquiry code that you played, what I did is I modified the recording. So I made it a little bit longer so you can hear it better in terms of time, but also I lowered the frequency so we can actually perceive the call because the normal frequency is not audible to all of all of us.

SPEAKER_01: 46:12

Wow. Uh I think that speaks a bit to what we were talking about earlier with regards to how difficult it is to access or think about bats because they're at nighttime and we can't we can't see them and we privilege sight. But even if we were listening, we wouldn't necessarily hear them. They're they're stealthy in a in a way that's really which is probably what makes them really effective um hunters and and and at navigating the world. Um, so you've brought you brought this down and you've elongated it so that, and I think that's just so fascinating. So you've taken an experience of another animal, which you know Nagel very famously said, you know, we will never know what it is like to be a bat. Um but here we're starting to see how technology is making some of those kinds of possibilities or ideas of thinking about what it must be like to be a bat. Because I hear the sound, it actually makes me think of a gibbon, interestingly. That kind of like it's um fascinating. Okay, I'll play I'll play the inquiry now and I'll play the response once more and then the response. So now they've found a leaf and they're going to settle again.

SPEAKER_02: 47:28

Yes, exactly. So now that after the response to like this really long, that's that's the very strong impulse to go into the into the leaf. So yeah, very effective.

SPEAKER_01: 47:43

Incredible, incredible. And you're saying that there might even be some dialects and different ways in which this inquiry response is happening, not only across species, but across different populations within species.

SPEAKER_02: 47:56

Um yes, although these calls that I I showed you, they're only emitted by these species. Uh, so far, this call and response system has only been found in this the species that I work with, uh, this this queen bat. In we know that in other species there may be uh calls that they're using to locate each other when they're uh searching or entering a roost site, but we really don't know that much, and at least this this, like I said, call and response system hasn't been found in any other species of bat. So, and there is some evidence that there for this particular system there may be dialects like populations far away, they're still using this inquiry response calls uh within these species, but their the calls differ quite a bit between regions, even for example, within Costa Rica. So there may be something interesting there in terms of dialects, but there's incredible. We still need to work a little bit more on that.

SPEAKER_01: 49:03

Yeah, language, culture. It's um it's fascinating. That thank you so much. I think I feel like we've just scratched the surface. I wanted to ask you so many more questions about like about I actually even wanted to ask you a bit about biosecurity and how we can better look after bats. So maybe you you can give us a hint at what we can do to be good neighbors to bats, uh, and then possibly tell us a bit more about what you're working on now. And um, oh no, if you have a quote, I almost forgot. Do you do you uh have a quote? I'm I'm gonna backtrack. I'm asking too many questions. The first question: if we want to be good bat neighbors, what could we do to be better bat neighbors?

SPEAKER_02: 49:49

There are different things that you can do. Definitely don't, for example, because of the majority of species are insect eaters. Uh, I think, for example, not using pesticides to control, I don't know, you know, simple pests, even in your back backyard or um, if you have a farm, try not to use pesticides as much as possible. And then, you know, what I tell people here in Costa Rica, because we also have a lot of uh pollinators and fruit eaters, that it's very possible that they they don't have enough resources because we have taken away the trees or other you know flowers that they may use. So if you can plant uh flowering or fruiting trees that bats like in the area where you live, then that that really makes a big difference. Um the other important thing is that you need to consider that one very, very critical resource for bats are their roosts, the place where they spend their day. So if you know of any bat roosts, um you know just try to take care of them, don't destroy them. That's very critical for their survival as well. And another simple thing which might also not only help bats but also a lot of other organisms, is to turn turn off the lights during the night. Um, I think it's just the the lights are not something normal in in animals' environments. So if you can try to turn off the light, I think that's also always wise uh advice.

SPEAKER_01: 51:26

I think those sound really practical and doable for um for many of us is plant some more flowers and and fruit if it's possible. I mean, I think berries are really easy to just put out on a windowsill and uh um, you know, not for us, but for others. Let's give back to bats a bit and switch off our lights a bit more. I think those are both doable. And as we've learned today, there are a variety of different bats. So maybe doing a spot of homework on who your local bats are uh guaranteed there are organizations because they we think of birds and bees as being these really big pollinators, but bats are also just I mean, we shouldn't only protect them because they pollinate, we should protect them because they're awesome and wonderful and they deserve to be in this world. Um, but they are also they are also doing really important things in the world, and if we can enable that, then we should. So thank you. Um okay, so quote time, quote time. Now, what's your quote on?

SPEAKER_02: 52:27

This is I one of the books that I really, really love is the a short history of nearly everything from from Bill uh Bryson. I love yes, and so he has lots of very interesting quotes. So he's quoting himself uh Martin Reese, which is a British astronomer. And I really like this because I think it shows a lot of the you know lack of information that we still have about a lot of topics and bats in particular. So he says our present satisfaction with our state of understanding may reflect the pity of the data rather than the excellence of the theory. So I think it just shows, yeah, we're we're happy with what we know, for example, in this case about bats, but it's just that there's so much more to learn that we really need to keep delving uh very deeply into all of these topics so we can be better at providing information that's going to be ever increasingly more useful for protecting bats and learning how to love this group of mammals much better.

SPEAKER_01: 53:39

So and I think that quote also so beautifully shows kind of the we often think of the natural sciences and the social sciences as being kind of separate from one another. Um, but I think that for me at least that quote shows how important it is that we have both of these happening at the same time, that we have social scientists and philosophers that are willing to ask these, what seem to many scientists to be esoteric questions about how do animals experience the world? What is the importance of this experience? Um, just because we don't experience sound in that way, does it make it less important or significant? We need those critical scholars and those philosophers to ask those questions and imagine those things. Um, while at the same time, we also need uh natural scientists who are going into the field and getting their boots dirty and spending time with the bats and and learning about them that way. Um and and we're not always, I think, symbiotic as physical scientists and social scientists. Sometimes we're at loggerheads with one another. And I and I think I don't know, it's it's there's beauty in realizing that we're both kind of working towards the same same goals of looking after these really beautiful species, and and I think that we both bring important stuff to the table uh in terms of that. So I really love that quote a lot. Okay, so uh we're we're nearing the end of the show now. If folks are interested in learning more about your work, uh and yeah, they just want to learn more about bats or more about your work, where could they learn and find out more?

SPEAKER_02: 55:12

Um I have a webpage that it's www.batscr, like batsincosta rica more or less, uh, dot com. And uh I also have a Twitter account, um Morseglo. Yeah, and I have a research gate page also if they're interested in looking at my publications up to date.

SPEAKER_01: 55:36

Wonderful. I'll make sure that all of that is in the show notes. Um thank you for the the work you're doing and in helping us learn more about this really large order.

SPEAKER_03: 55:48

Thank you, girls.

SPEAKER_01: 55:53

Hi everyone. So Hannah's not going to be joining us for an animal highlight today, and that's because this whole episode has, in effect, been an animal highlight. But Cheryl Tip, who you might remember was a guest earlier on in the season, had sent me two really cool recordings of bat and bat sounds. So I figured why not share them with you here. Uh if you don't recall, uh, Cheryl Tip is the British Library's curator of wildlife and environmental sounds. And she's been sending me a couple of really cool uh sound clips throughout the season that you've you've been hearing, and I think they've added a great deal to the show. Anyhow, the two recordings that you're going to be hearing today were both made by Richard Ranft, who was a zoologist by training and worked at the British Library Sound Archive for 25 years, and he curated over 150,000 recordings of animals. The first is the echolocation calls of a common pipstrel hunting over a lake in Kent, England. It was recorded in May 1988 at 50 kilohertz. Here it is. Common pipstrel. Isn't that just an incredible sound? There's something just really magical about just hearing the sound and thinking about that. And and for me, it's such a foreign sound and trying to locate and think about it. Really amazing. Um, the second sound or the second recording that you're going to hear is echolocations of a nocule bat feeding over grass fields, also in Kent, England. This one was done in June 1986 at twenty two kilohertz. All right, so that's it. I just wanted to share with you two really cool sound recordings. So in this episode, and with these sound recordings, you've kind of gotten a sense of the variety of sounds that uh bats make and how different echolocation can sound and how important it is that we record these, but also how awe-inspiring I think and incredible the sounds are just in and of themselves, to just hear them. I think it's really mind-boggling. Uh, I think these sounds are just incredible, and I've terribly enjoyed kind of finding them and learning a bit about animal sounds. But that's all I wanted to share with you for now. So uh thank you so much. As always, a huge thank you to Animals in Philosophy Politics, Law and Ethics Apple for sponsoring this podcast. And another thank you to the Sonic Arts Studio and SAP Lab, which is also known as the Sonic Arts of Place Laboratory, for sponsoring this season. Make sure you join us for the next episode, which will be the last of the season. Yay! And it's going to be a grad review where we're going to stitch together a whole bunch of the different tensions and opportunities that we've learned throughout this season. It's been a rather elongated season, it's been quite spread out. So I think the grad review will be a really neat and cool opportunity to bring all of these themes and threads together. So I hope you join us then.

SPEAKER_00: 1:00:32

With me, Claudia Hötenfelder.com. That's I R O A R P O D.com.