Scientists tried to study sloths... it didn't go well

Well, with sloths nobody really knew anything about them for a very, very long time, which surprised me because I thought, well, you've got this animal that just sits around in trees all day. How hard can this be? He got one. He's caught it. There we go. All across Costa Rica, scientists and conservationists are working tirelessly to understand and protect some of the world's most peculiar creatures, two-toed and three-toed sloths. There is so much work to be done because sloth research is in its infancy. The science world is just scratching the surface when it comes to understanding their anatomy, behavior, and perplexing survival strategies. As Dr. Becky Cliff has realized throughout her career, and as I too would come to realize, sloth research and conservation is not easy. And on top of this, for a long time sloths were woefully misunderstood. Those days sloths were still considered almost like vermin. When an animal lives, you know, 40 feet in the air or 60 feet in the air, and you don't see it moving, you don't see it doing anything, it's kind of stupid. The kids would throw rocks at them. People thought they were dirty, dangerous, because they'd see these long claws, so... Fortunately, public perception of sloths has improved drastically in the last few decades. However, the science is still lagging behind. The majority of science on sloth biology has happened in the last 10 years, and there's still so much we don't know. But luckily for scientists, the Sloth Sanctuary of Costa Rica has opened its doors for scientists to come and collaborate, carrying out important experiments with some of the resident sloths. Dr. Mike Butcher is a professor of zoology and biomechanics and investigates the structure and function of the muscular and skeletal systems of many animals. He specifically wants to know how animals are specialized for movement in the treetops. And sloths are the perfect subject. He wants to understand which muscles get activated as a sloth walks upside down along a branch. Inverted locomotion like this is unique and little understood. The goal here is to better understand how evolutionary specialization of mammals, not just sloths in particular, but how mammals adapted inverted suspensory locomotion. And at the sloth sanctuary, his research to investigate this was about to commence. The first step in a study like this is to implant very tiny electrodes in the sloth's muscles to see which muscles get activated as the sloth moves. So we chose eight muscles of the forelimb for which we wanted to implant what we call fine wire electrodes. So what we do is we sedate the animal with a very mild sedative. Once the animals go down, we start palpating for each individual muscles that we want to target. Using a very fine needle, they then insert the electrode into the muscle of the sloth. The electrode itself is a very fine wire, smaller in diameter than a hair. Once implanted, the electrodes wirelessly transmit EMG signals to what is called a bio-radio. Colorful dots are also fixed to the sloth's joints, so that during this experiment his movement will be captured with cameras in 3D space, sort of like a motion capture suit. Then it's time for the sloth to wake up. And then about 10 minutes or so after the animal metabolizes that reversal agent they start coming back to consciousness. They'll notably start gripping whatever they can find. So we usually have a finger or two in their foreclaws so they can flex against us and we use that as our test of how much consciousness they've regained. And now the experiment can begin. Outside, there's a beam which is equipped with a force sensor that will transmit data to a computer. It will measure the force of each stride, while the electrodes record data about which muscles are being activated. For this to work, They need the sloth to walk in a straight line across the beam. But getting the sloth to cooperate is easier said than done. There you go. Let's get him going. Here we go. Foot on. No. He's like, nah, I'm done. OK, that's too much. OK, it's got you. Oh, it's going to be right high. Yeah, right high. Let him go. It's good exercise for AJ. And one more. Perfect, okay. Stephanie, are you good in this? Oh yeah. Are you seeing this amazing performance? Fantastic. As the trial continues, Jojo the sloth does get them the data that they need and then he decides he is over it. Once he shows any signs of frustration, the experiment is brought to a close and Jojo is thanked for his contribution. Other experiments that day used a similar setup but without the electrodes, focusing only on the force plate on the beam. This setup proved to be even more tricky, with the sloth doing literally the exact opposite of what the researchers wanted at every turn. They wanted the sloth to walk forward, he walked backwards. They placed him backwards trying to use reverse psychology, and he still walked backwards. They wanted him to walk on their beam with the force plate, he wanted to reach for the gazebo beam. They put up a cardboard box to block him from reaching the gazebo beam, he pulled the cardboard box down. They lowered the beam so he could less easily reach the gazebo beam, and he still wanted to grab the gazebo beam. Ultimately, the researchers decided this setup wasn't going to work after all. Such is life working with any animal, and particularly sloths. With captive sloths, their cooperation is hard to come by. With wild sloths, research is even harder. They've got 64 million years of evolution behind them, making them really difficult to see. They're literally masters of secrecy. It's impossible to do observational research on an animal that's so well camouflaged. For this reason, Becky and her team at the Sloth Conservation Foundation use radio collars on wild sloths. The idea is to be able to find and monitor wild sloths with more consistency. So the radio collars that we use on sloths are called VHF radio collars and they give out a radio signal and we have a giant antenna that looks like a sort of UFO finding device and we wander around the jungle receiving that signal. It's like a big game of hide-and-seek. She's in that tree. You follow the signal and it draws you closer and closer and closer. And when you get within a certain distance, you just have to look for the sloth with your eyes and the binoculars. Then go behind it to the branch in the sunlight. I think she's on that side. I'm wondering if I'm getting a bounce. Yeah, it's definitely challenging. definitely challenging. You can go out and spend hours searching for that signal and it can point to a tree so you know the sloth is in that tree but you cannot see it for hours and hours and you just end up staring up at the canopy thinking is it a bird's nest? Is it the sloth? You don't know until the sloth moves and it's not like you're in a really nice environment. These are dense tropical rainforests with honestly like mosquitoes going in your face, there's There's snakes, there's spiders and ants. Everything wants to hurt you. And you have to spend hours out there. But with some patience, eventually you just might find the sloth. He's doing a mango special where he is right here. He is right, right, right here. Now, is he low or is he high? He's higher up. Fuck you. Yeah, there he is. Found him. Well done, Amanda. No, I found him in that tree, though. So we need to take some data. Look at him. He looks so cute. Scrumptious. Once it's found, information about its location is recorded. Everything from what type of tree it's in, how high up it is, or how near the road it is are all valuable data points. But the radio callers can only help you find the sloth once you're already near it. They can't transmit any useful data themselves. The people on the ground must do that part themselves. And because sloths love to be basically invisible, this data acquisition can be nearly impossible. So we had to come up with a way of knowing what they were doing without just sitting and watching them. So the Sloth Backpack Project is what I developed for my PhD initially. Inside the backpack, there's little micro data loggers called daily diaries, and these are packed with sensors. They measure eight different things 32 times a second, and it's things like accelerometers, it's got a compass in there, a pressure sensor so we know how high in the tree the sloth is, a light sensor, a temperature sensor, all different things. Once you put that on the back of a sloth and you get all the data back, you know exactly what the sloth was doing and where it was doing it. So the first goal I had with the backpack project was really to understand what are sloths doing in the wild? What are they doing? When are they active? Where are they active? Where are they feeding? What types of trees do they like to use? We have now built up quite a good picture of that. And so now we've developed the project into something we're calling the Urban Sloth Project. So this is where we're putting these backpacks on sloths that are living in areas with different levels of human disturbance. So we've got super urban sloths that live in people's houses and restaurants. And then we've got sloths in primary rainforests that live in the perfect sloth habitat. So what we're able to do is compare how the behaviors of animals in different areas differ, and then create ways that allow the urban sloths to coexist alongside people more easily, more harmoniously, and hopefully help with our conservation strategies to protect them. And this science couldn't be more important because sloths are in trouble. Rescue centers here get about three sloths every single day, which is an astonishing number. And the reasons why are all because of humans, of course. So it's things like power line electrocutions. That's the leading cause of death for sloths in Costa Rica. We've got attacks by dogs as sloths are trying to move on the ground. There's road traffic collisions. But the Urban Sloth Project is making headway and addressing many of these issues. One important way to help sloths is to build sloth bridges, Ropes that connect parts of the canopy that have been disconnected, giving sloths a safe way to cross without using power lines or having to go to the ground. And building these bridges, as I learned, is an installation process easier said than done. First, the team uses a slingshot to try to get a guide rope in the desired branch of a tree. This takes careful aim. Sometimes they get it on the first try, other times not so much. Then, once one side of the rope is secure, the other end gets brought up into the tree manually. This requires some careful climbing. Once both ends are secure, the rope is pulled as tight as possible. These bridges will help sloths, but also other canopy creatures. The team will often install camera traps to see just who is crossing. The Sloth Conservation Foundation is also working to reverse habitat loss by planting tree species that are favored by wild sloths. These trees are often planted on private land, where trees were initially torn down for development, leaving unnecessary and unwanted open spaces. With the cooperation of landowners, hundreds of trees are planted each year, which will then grow to fill the dangerous gaps in the canopy. And when it comes to sloth conservation, the most important thing we can do as people is to respect the space of these animals. People wanting to have a photo with a sloth or wanting to touch one or have one as a pet. So I just saw last week online, all these pet sloths being listed for sale in Florida. And there's a huge demand for them. They're selling for about $8,000 per sloth right now. But just for people to know that this isn't good for the sloths, they hate it. They don't want to be in captivity. They don't want to be held. They don't want to be touched. wild animals and they should be in the wild. And yeah, if you are offered an experience where you get to touch one or hold one, just know that that's not in the sloth's best interests. And if you want to love them and respect them, do it from a safe distance. Before traveling to Costa Rica, I knew I loved sloths. For the same reason anyone does, because they're so endearing and cute. And now, while I still think they're endearing and cute, I also now understand how particular they are, how unusual they are, and how difficult and important their conservation is. Sloth conservation may not be everyone's dream job, but it is one that the sloths will desperately need for their ongoing survival. This is why meeting the people who actually do this job left such an impression on me. The scientists working on sloth conservation pour so much care and passion into a role that most people will never even think about. And seeing that up close was one of my favorite experiences in the entire history of this channel. I originally created this video alongside my Insane Biology of Sloths documentary as part of an idea I called Field Notes, a behind-the-scenes look at the scientists who work brings these stories to life. I've continued this series for years. Most of the videos are just recorded, unedited interviews, since I realized traveling to interview scientists in exotic locations is fun, but really expensive and time-consuming. So instead, I talk with them over the internet. Sitting down with these researchers is still my favorite part of the entire video making process. I use snippets of these interviews in the main videos, but the full conversations get into so much more depth. I see these interviews sort of like video podcasts. An hour or so of thoughtful conversations with the leading experts on various animals. 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