[00:00:00] Speaker A: What animal sleeps up to 20 hours a day, moves at a glacial pace and only comes down from the forest canopy once a week to do their business?
I'm talking about slaws, some of the most peculiar, most loved and fascinating mammals on the planet.
Welcome back to Rewildology the Nature, a podcast that explores the human side of conservation, travel and rewilding the planet. I am your host, Brooke Mitchell, conservation biologist and adventure traveler.
International Sloth Day is this Saturday, October 21, and the show is celebrating with our first minisode to get us slocicated slothucated. Slocicated, whatever version of that fun word you want to use. Today we'll hear from Sam Troll, co founder and executive director of the Sloth Institute, and DRN. Smith DVM, wildlife veterinarian and the world's leading pygmy sloth researcher. We explore the natural history of the sloth, the differences between two fingered and three fingered sloths, and the closest relatives in the evolutionary tree. We dispel myths about why sloths move so slowly and why they come to the forest floor to defecate instead of staying in the canopy where they live. We also take a deep dive into the lives of the pygmy sloth, how it evolved, its top threats, and what we need to do today to conserve it. So pour yourself a warm cup of coffee or tea, or if it's after 05:00 p.m., maybe a glass of wine, settle into your most comfiest of positions and get ready for a leisurely view into the wonderful world of the sloth.
Our first Slothy teacher is Sam Trawl of the Sloth Institute based in Costa Rica. Sam and her team rescue, rehabilitate and release sloths back into the wild. Scientifically research sloths, educate the public about sloths and are working to conserve and protect the group of animals for the future. And also, too, before we dive too much deeper, I just want to take a moment to chat about slaws themselves, since, again, people probably don't know much about the natural history and what these creatures actually are right now. They're just really hip and they're cute and their faces are plastered on a whole bunch of different paraphernalia of things.
[00:02:47] Speaker B: Like my background.
[00:02:48] Speaker A: Yeah, come on. That is the cutest background.
[00:02:51] Speaker B: That's my picture, so I'm allowed to put it there.
[00:02:53] Speaker A: I just like one. Just so cute.
[00:02:56] Speaker B: So cute. Super cute. So cute.
[00:02:59] Speaker A: But if you could just take a second, just explain a little bit more about slaws and even just whatever facts you want to list off, but just educate us about these amazing creatures.
[00:03:11] Speaker B: Yeah, I think one of the first things to point out is that the two different kinds of sloths are not closely related. So the two fingered sloth and the three fingered sloths. And I say two fingered and three fingered versus two toed. And three toed because it's much more accurate.
The difference in the number of digits is on their fingers, not on their toes. And they also unlike a dog, for example, that has four legs. Sloths don't have four legs. They have two legs and they have two arms. And they use them that way, similar to a primate. They don't eat with their feet, they eat with I mean, some primates do actually eat with their feet. But in general, just like us, we use our hands and our feet differently. So sloths are the same in that way. So just to start with two fingered and three fingered. And I feel like it's much more respectable to call them that way because when you call them a two toed or three toed, it's like ignoring the fact that they use their hands in a similar way that we do. Kind of just like lumping them in with less evolved animals.
But anyways, yeah, so two fingered and three different kind. There's six species total that is currently recognized by science in the world. And they're only found in Central and South America in the wild. And in Costa Rica, there's two different species. So there's the Coleppus Hoffmani, which is the two fingered species in Costa Rica, and Bradypos Varieguettis, which is the three fingered species in Costa Rica. And the two different kinds have been evolving separately, they think, for probably about 40 million years.
And so what that means is the similarities that we see are not based on a common ancestor. They're based on convergent evolution, which actually makes cloths the most extreme example of convergent evolution in mammals. Which is pretty cool. Whoa. That is cool.
It's super cool. And so they do have a lot of similarities, but they do also have a ton of differences. And actually, this is my favorite fact about sloths, but the number of cervical vertebrae that they have is different. So, as you may know, all mammals have seven cervical vertebrae except for manatees and sloths. And manatees have six, but they always have six. And with sloth, with two fingered sloths, they can have between five and seven.
With three fingered sloths, they can have between eight and ten. What that means, that three fingers, floss have more bones in their neck than a giraffe, which I just think is crazy cool. So is that how they can do.
[00:05:54] Speaker A: That whole turn around with their neck?
[00:05:56] Speaker B: Yeah, exactly.
And one of the things I always like to tell people when I start explaining all the weird things that there are about sloths is that for the most part, most of the unique morphological characteristics that they have and the unique behaviors that they have. Most of those things can be explained by either their need to conserve energy or their need to be invisible in the forest, because that's how they survive. They survive by not wasting energy and they survive by not getting eaten by predators because, unfortunately, they don't have a lot of ways to protect themselves from predators except for going unnoticed. So they need to basically be invisible. So by being slow they're not only slowly conserving energy but they're also silent. And we definitely see this in the thousands and thousands of hours that we've been observing sloths in the forest. When they're moving you barely hear them so you need to have a visual and you need to keep that visual or you're going to lose your visual because they're so silent. And so with the cervical vertebrae question with the three fingers loss it really helps them to turn and look and maybe check out some noise behind them to see if it's a noise they should be worried about without moving their whole body. And by not moving their whole body what do they do? They conserve energy and they bring less attention to themselves because they're moving a much smaller piece. So for the most part most of the things that's weird about them can be explained with those two things in mind which I think is pretty cool. They are also excellent swimmers. Both kinds of sloths are excellent swimmers. There's a really ugly rumor going around that two fingered sloths can't swim and it's not true and I don't know where it started but it's not true. Both two fingered and three finger sloths are excellent swimmers and again that makes a lot of sense because all the places where sloths live there are bodies of water.
In Manuel Antonio for example there's the ocean and there have been sloths found like floating on driftwood in the ocean. So being able to swim of course helps keep them alive. Out there though I don't think they're any match for really aggressive waves. But still being able to float and being able to swim is really important. And then of course rivers know sloths are found all through the Amazon of course. So in places like Mean the rivers just flood really easily with heavy rains. So being able to swim is essential for not drowning in a place where there's a lot of water that you could fall into. But also if you think about it rivers are like the roads of the natural roads of the forest. It's what separates different parts of the forest from another. And so by being able to swim, they're able to get from one side of the forest to the other to get to whatever things that they need and also to get there with using less energy, because they use a lot less energy swimming than crawling on the ground.
So the fact that they're good swimmers I think is pretty cool. What other facts do I love about sloths?
[00:09:03] Speaker A: Why do they come to the ground.
[00:09:04] Speaker C: And when do they do that?
[00:09:06] Speaker B: Oh man that is literally every ecologist favorite question and I mean it's totally cool that you asked it but I have to say it's like oh my god the people obsessed about something else please. Because people are so obsessed with why they come to the ground and honestly, I think the reason why people are so obsessed with why sloths come to the ground is because they erroneously assume it's more dangerous on the ground for a sloth than it is in the tree. But that's never been proven. It's just this assumption that people keep in the narrative to making the question of why would they come on the ground. But honestly, I think they come to the ground because it is safer to come down to the ground than it is to stay up in the trees to go to the bathroom. So the main reason why they come down to the ground is to go to the bathroom. And sloths, as you've probably heard, can hold their urine and feces for about a week. They don't have to hold it for that long. They don't usually hold it that long in captivity if they're well hydrated and eating enough food. But in the wild, they can hold it that long. And so by the time it's been a week and you haven't gone to the bathroom, as you can imagine, they've stored up quite a lot of material and they can actually lose up to 30% of their body weight every time they go to the bathroom.
[00:10:23] Speaker A: Wow.
[00:10:24] Speaker B: Which is super cool. I totally wish I could do that. That's a download. Exactly. Right before this zoom, I would just been like, well, I just need to go to the bathroom.
Look so much better for yeah, fit into that party dress. But sadly, even though I work with sloth, I have not been able to adapt that superpower.
But yeah, so it's a lot of fluid and material that comes out every time they go to the bathroom. So if you can imagine, doing that up from the treetops would be extremely loud even if they were doing it, every day is so loud. For example, every time I hear a trooper howler, monkeys above, they love to go to the bathroom in unison for some reason. But you know exactly where that monkey is in the forest. Even me with my limited human hearing, knows exactly where that monkey is just by listening to them urinate and defecate from the treetops. So I know an ocelot or a bird of prey is going to know exactly the location of that sound if they go from the treetops. However, by coming down from the top of the tree to the ground, you don't hear anything like it's super silent. And they go peacefully and quietly, very slowly down the tree, do their business, and then come back up. So the only negative to coming down to the ground is that it does use some more energy because obviously coming down the tree rather than staying up at the tree is going to use more energy. But if you're going to use more energy for something, there's no better reason than to not get eaten because, well, right, that's the end. Don't need to conserve any more energy because I don't need it anymore.
So I think that that's why they come down to the ground to go to the bathroom. There have been other theories but there was one that was actually described by some really good scientists but not necessarily sloth experts that said that the reason why they came down to the ground was because of mutualism between sloth, sloth moths and the algae in their hair. Because sloth moths do lay their eggs in the feces of the sloths. And I don't know if you're familiar with sloth moss, but it's the species of sloth, I mean the species of moth that lives only in sloth hair. And it is pretty cool. Sometimes it looks really annoying for the sloths because they'll be all on their face and they can have like hundreds on them at a time. They usually have less. I mean it really varies. Sometimes they have none but they can have a ton of sloth moths on them at once and they're only found on sloths. So this theory was that the reason why they come down to the ground is so that sloth moths can lay their egg in their poop. And the reason why the sloth moths are important to the sloth is because when they die or when they get certain things in their hair or poop like poop in their hair, it helps the algae to grow in their hair. And then the reason why the algae is important to sloth, they hypothesize is that the sloths were eating the algae off of their hair and using it for nutrients. And so that secret solved. Like that's why they come down to the ground to poop. The problem with that is literally in what, like 7000 hours we've been watching sloths, like literally observing them scientifically. Never once have we ever seen them lick their hair the way a cat does. They don't do that at all, not once. They might eat algae, like they eat random things off of tree bark and different plants and of course the algae is going to be in the environment around them. I mean, where do we think it comes from? So they might be eating that algae but they're not eating it off themselves. So that kind of negates, that theory of why they come down to the ground. And it's also possible they come down to the ground for multiple reasons. Like why does it even have to be one thing? Right? Personally I think the most important thing is they don't want to die but there could be multiple reasons why.
Yeah, that makes total sense and hopefully.
[00:14:12] Speaker A: That answers everybody's question for that exact reason. So I was like, I have to ask it, I have to ask it.
[00:14:17] Speaker B: But yeah, no, totally.
[00:14:19] Speaker A: That's a great response, great answer. And then from an evolutionary history standpoint, what is their closest relatives? Where are they placed in the tree of life? This very special, unique creature.
[00:14:35] Speaker B: So they're in a suborder of mammals called xenarthrins. And the other xenarthrins that exist are ant eaters and armadillos. And so those are technically their closest living relatives. Both I have to say there's something special about xenarthrins in general because anteaters and armadillos are both really fun species to rehabilitate. Like, they're characters, total doofuses. Total doofuses, like, total idiots. I adore them, they're so funny.
And sloths have similar characteristics to that. So I guess being a doofus is a part of being as an Arthur and I don't know, but they're amazing.
I love them both. So, yeah, they're their closest relatives. And actually, the classification used to be called Edentata, which means having no teeth, because anteaters have no teeth at all. And then sloths have interesting dentition. That's another thing that's interesting about them. So they have no incisors at all, like no teeth up here, and only molars and premolars. And so three fingered sloths only have little tiny nubby molars and premolars that continuously grow so that they can chew the leaves and all the tough things that they chew on a regular basis to feed themselves. And then two finger sloths have the molars and premolars, and then they have these pseudocanines, which are really big, like typical canine looking canines, but they're not technically canines because they're positioned a little bit further back, so they're technically premolars. They call them pseudo canines, but they are a big, sharp teeth. And a lot of people ask, well, if they're vegetarians, why do they need big, sharp teeth? But biting into mangoes and different hard seeds, you do need some decent teeth to get into really hard flesh. And they will eat, especially the two fingereds do eat a bit of fruit in the wild, but also as peaceful as I say sloths are. And as much as they do generally mind their own business in the wild, which is one of my favorite things about them, they don't shy down from a fight with another sloth if they need to. And two fingered sloths especially can be quite aggressive with one another, with one another, especially if they're, like, defending territory or if it's two males defending, wanting to go out on a date with a young lady sloth. So they will use those teeth to bite each other. And they have extremely strong jaws, all that chewing. Yeah, they can chew through rock. And we've actually had a volunteer who was trying to help rescue a sloth off a wire and she got bit and it broke her finger.
[00:17:11] Speaker C: Whoa.
[00:17:11] Speaker B: She had to have surgery. Yeah. Sloth bites are no joke. Sloths are no joke. I mean, like I said, they can break bone, legit can break bone, but also, they don't have the cleanest mouths ever.
They have a nice healthy community of bacteria in their mouth throughout their intestinal system to break down all the cellulose and the things that they eat. So it's natural and it's good for them but it's not so good for when you get bit. So you have to be super careful for it not to get infected. And I have colleagues that she got bit in her arm and had to have parts of it surgically removed because the infection got so bad. So it's good not to touch sloths not only just for the sloth but also for yourself to make sure not to get bit.
[00:18:02] Speaker A: Our second slothy teacher is DRN. Smith DVM. DRN is a wildlife veterinarian who also wanted to contribute to conservation and she fell in love with her country's endemic species, the pygmy sloth. For over the past ten years she has been studying the species alongside local indigenous communities that live with the animals.
[00:18:24] Speaker B: Oh, I can't wait to really start.
[00:18:26] Speaker A: Diving into these sloths.
Okay, I think maybe a logical place to start would be people probably don't even know there is such a thing as a pygmy sloth. So maybe let's start there.
Where is this pygmy sloth and is it different than its, I guess, quote unquote, bigger counterparts? What makes this species special? And then I really want to get deep into your project itself.
[00:18:56] Speaker C: Yes, well, yeah. In Panama we have three species of sloths. The Bradipus barrieratus with the three toad sloth is plenty distributed in all Panama. And the colepus of Mani, the two toed slots plenty distributed in all the mainland or in Panama. But we have the unique species, an endemic one. The pygmy sloth was the only one in critical endanger who lives in a small island called Escudo de Verawas island who is located in the Caribbean side of Panama. Why is so important? Because it's the only one species okay, this is difficult to pronounce. For me it was dwarf.
[00:19:46] Speaker B: Dwarfism?
[00:19:47] Speaker C: Yes.
[00:19:49] Speaker B: That's not an easy word.
[00:19:52] Speaker C: Yeah, this is experiment something that we know as dwarfism phenomenon. That's why it's so different to the other species their size, the weight less than the species from the mainland and of course it's in critical endanger because live in a very small island. So any kind of disturbance in this island is going to affect directly. This species in general looks similar to the Bradipus barrier gat when was discovered as a new species in 2001 by Anderson and Hanley they made morphological measurements of the school of everything of the body and they compared to the different slots from the island in the archipelago of Boca del toro. That's why the slots who live in the oldest island from the archipelago in Boca del Toro is a dwarfism phenomenon, has that waterfism phenomenon. And this dwarfism phenomenon is when a species, a mammal, a big mammal lives in a specific area, probably don't give them too much resources. Eventually through the years it's going to be smaller or reduce their size while species or animals, smaller animals in that specific area that is small like an island has a lot of resources probably is going to be a little bit more bigger, a bit bigger than animals from the mainland. That's why in de vera we have the pygmy sloth who is dwarfing, but we have the human bird who is a guyan human bird in comparison to the male. So that's why the pygmy slow is so important because it's unique and of course it's part of an island who is too small. So that's why it's endangered species, critical endangered species.
[00:22:15] Speaker A: So then what is the biggest issues that they're currently facing or the biggest threats?
[00:22:23] Speaker C: Well, this is very interesting because in the beginning of my project, when I was there and I was talking with the indigenous community, because when I started, I start to walk with them, to be with there, to live. With the indigenous community, just to know more about what they know about the Pygmy slot, what they know about the island. And how can I give them more knowledge about how the species living there and how to protect them in the future.
And in that period of time, like seven years ago, one of the big traits was the number of people there using a lot of people there using their trees, the mangroves, because they're using the mangrove for cooking. Some. Other important trees because they're using to build houses in the island and a lot of fishermen and divers living in the island during the season just to use their resources from the island but at the same time using the forest. That probably is of course important from the pygmy slot.
But now one of the threats that probably not going to change too much from that time is the increase of tourism in the island. Now everything changed. Now there are more people with tourists using the island as a beautiful place to stay there, and the pygmy slot is one of the attractions. So that is something sensitive because it's an important species and we have to increase our information about their treats. I mean, if they are healthy, we are doing genetic studies too, and this kind of perturbance or disturbance from the people, more anthropogenic activities on the island is going to put this small animal intrigue.
And that is the problem that we are facing now with the pygmy slot. Obviously, it's one of the most flat species and it's charismatic species, but at the same time is attractive for our track, called the legal traffic of a species. So this is another threat that the business law is.
[00:25:10] Speaker A: So I want to make sure I completely understand the new threats that are coming in. So are these people from mainland Panama coming and taking them out of the wild and putting them in the illegal market? Or are they just setting up tourist selfie stations? Or is it a blend? Or is it the indigenous community seeing a way to make more money through tourism?
Is it a blend of all of this. What have you seen on the ground here?
[00:25:41] Speaker C: Yes, well, recently we know that everything is blended. Now there are tourists that go there and they want to take a picture with the pygmy slot. They want to hold the pygmy slot and take picture. And we know that because indigenous communities, they are small from different areas and everybody knows themselves. And when I go there, they say, oh, I brought some tourists and they wanted to be close to the pygmy slot. And sometimes there are not people from the area. I mean, they are from the mainland, not exactly from the coast near Scudo, not from those communities, because in 2013, something not good happening on Escudo. They were taking or ten pygmy slots for somebody who wants to have it in a private collection in United States. In 2013, that happened and everything changed since then. The indigenous people get mad with everybody because I lost one year of research, because they closed the island for everybody, because they started to don't trust in anybody since then. And the attention from the pygmy slot increased because now they know that this small species, this animal, that they probably, they don't care that is there because they are doing something.
They are diving for lobsters, they are fishing, they are not exactly seeing the pygmy slot as a resources. It's just like the slot there. And now they know that people around the world want the pygmy slot. So they were more aware about what are you doing here? And that was probably one of the questions that sometimes they ask me when I was there in the beginning, what are you doing here? Why you want to protect this species?
And of course, on the other hand, we have that kind of people with irresponsible operators that go to Scudo and they just want to be there to take selfies, not exactly to hold the animal, but at the end, what they receive from Escudo, nothing. Escudo is more than just a beautiful island. Escudo has a lot of story to tell with the people who visit them. It's a legacy from the indigenous community people. It's so important for them.
They call dego. They don't call escudo. Dego is the name of the other indigenous. According to their stories, the Dego indigenous fight with the Nove indigenous and then the novice win that fight. And finally the Dego became roped in. Escudo became part of the resources from Escudo. And I remember in the beginning of my research when I was there and I spent the night with people around and I was stories of Espudo, some of them, they were scared to be to the forest, to go to the forest. They just go to the beach and they have their small houses there, temporary houses, and they never go to the forest because they don't feel that it's important. Sometimes if they have to log in, they do, or they did in that moment. But they don't feel that they have to go inside the forest because some of them, the oldest one or the elder people were scared. But the young people, they don't care, they don't believe in those stories because part of the culture is the indigenous. Sometimes they are losing their stories, the stories telling from the eldest one is now losing from the youngest one and now they don't understand what is. So it's difficult for them to connect why the island is so important and why they don't go never visit the forest inside the forest of the island. Because for them, now it's so easy to go there and probably they want to explore another opportunities of incomes and that's why we always persistence to do education in the communities because people change, people need to work, need to maintain their families in some way and Escudo probably is the only resourcer. So we really believe, and I believe that the only way that Scudo is going to be there forever, or at least all the resources there are going to be enjoyable for more than we want. Or for more time.
Is just do a sustainable tourism leadering by the people from the communities and it's a good way for them to see the school as okay. I can receive a resources from this island and I protected the island too.
If they start, and this is something that I always wanted to let them know. If you destroy the mangrove area, which is a really small part of the island, or you destroy some trees that probably are important from the pygmy slope, but you don't know because we are in that process to understand that at the end what you're going to show to the tourists?
[00:31:43] Speaker A: Nothing.
[00:31:45] Speaker C: They're not going to see the mislaw, they're not going to see anything. Just what even the marine resources from the island is still unknown.
[00:31:55] Speaker B: How is it?
[00:31:57] Speaker C: There are a lot of study that we have to do there and it's not an easy place to work because it's remote and you need a lot of work with the community and being persistent.
[00:32:13] Speaker A: Okay, so we have all of this information and you're actually there, you're invested in the community, they've welcomed you. Now what are you actually studying? What is your research, what kind of questions are you looking to answer? And maybe if you wouldn't mind sharing, what have you discovered yourself in your work so far?
[00:32:32] Speaker C: Yeah, well, in the beginning, we were with the simple thing, how many picnic slots are in the island? And this is a question that probably the people still ask me, and I say, okay, we are in the process to analyze all the data, because in the beginning, we were changing a lot of the methodology with my advisor, because it's not easy. We were concentrate to the mangrove area so we have permanent transect there and we walk to the transit. Every year, twice. So we have that number of individuals that we probably know how many are in that part and if something happened or any variation, put everybody in alert that something has happened. But still we have to analyze all the data collected since 2014, so it's a lot of work. And also we include the behavior of the pygmy slots. So we put some GPS color to ten adults, females and males, and actually all the pygmy. Slots colored, we put November name. So the people my team, according to the personality of the slot, we just give some specific names. And it was good because when we have to return, because they stay with the color for a year. So the time that we were there just to see that everything was okay, they come with me and they start to call them with the name. So they remember the name that they given to the picnic law. So it was funny and it was perfect.
So it was a part of the project to know the home range of the species on the island. And also we are in that process and probably with the preliminary results. It's not done different from the bradypus barrier in mainland. So it's interesting everything all the founds all the things that we are discovered through these years and also we include the genetic analysis just because we need to know the variability of the species in this small island that also is important. And we collaborate with botanics collaborate with us to identify plants that are using to the picnic slope as a refugee and as a diet. As part of their diet or as part of refugee. I think that is the name.
It's everything. And all this information is going to be really important for the conservation plan. From the species and from the management plan. From the island. Because now we know that the mangrove is not the only diet from the picnic law the leave from the mangrove trees. We know that there are more trees, important trees in the forest that are important. From the Pygmy slot and some of them are just connectors to go to other part of the island. So every year we know that there is a lot of information that we need to study with the Pimme slot. A lot of things is going to happen in the future with this thesis.
[00:36:14] Speaker A: If 30 minutes of sloth fun was not enough for you, please go back into the archives and check out the full interviews with both Sam and DRM. Episodes 46 and episode 74. Thank you for joining me on this wild adventure today. I hope you've been inspired by the incredible stories, insights and knowledge shared in this episode. To learn more about what you heard, be sure to check out the show
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