Tremaine: [00:00:00] I learned how to climb trees and ended up in the treetops, and I realized that it's such a different place than it looks like through binoculars, like staring, cranking your neck from the ground. I looked over at one point, and there was a howler monkey right nearby me, and it was just like, wow, this is where they actually live. But what a spectacular experience. It's just a really different world up there in the canopy. And, when we think about diversity up in the canopy, we really don't know what all is out there, what all we need to be helping to conserve.

Alexander: High above the forest floor, beyond what most eyes ever see, exists a parallel world where monkeys leap, sloths crawl, and porcupines wander highways of branches and vines woven through the trees. While we walk the forest floor, an entire ecosystem lives in the treetops.

In this episode of Wildlife Café, we're going to take a bit of a climb into that world. Wildlife Café is a series from World Wildlife Fund where we explore stories that bring us closer to wildlife and with people who are passionate about exploring and protecting our biodiverse world.

Tremaine Gregory has [00:01:00] spent many years researching tree dwelling species. She was one of the first researchers to use camera traps high in the canopy to study life in the treetop. And she works on ways to connect tree habitats over infrastructure like roads, to reduce habitat fragmentation for wildlife.

She shares her story with me in this episode and about what life looks like tens of feet off the ground and promising solutions to connect these habitats for tree dwelling species in the face of habitat loss.

Please be sure to like and subscribe to catch more episodes like this one and stick around for our conversation.

Alexander: Hey Tremie, how are you?

Tremaine: Hi Alexander. Great to see you.

Alexander: It's so exciting to have you on Wildlife Café. Welcome.

Tremaine: Thank you very much. It's an honor to be here.

Alexander: I am very excited to be talking with you and to hear so many of your colorful stories from your adventures and research on wildlife in the forest. You're an avid climber and have spent a lot of time up in the trees. Your whole perspective at that level can totally shift, I imagine, quite literally, but also [00:02:00] figuratively, and I would guess profoundly at a larger scale, when you see firsthand different worlds coexisting with each other, and ones sometimes that are invisible to us. So what does some of that rich life look like up in the treetops?

Tremaine: I studied primates for many years as a graduate student from the ground, and it wasn't until about, 8 or 10 years into my primate research that I learned how to climb trees and ended up in the treetops and I realized that it's such a different place than it looks like through binoculars, like staring, cranking your neck from the ground. It's actually a lot more pleasant, I can say. And, even though you're hanging on a very small rope. And I remember when I first was learning, I went to a training course in Panama. I looked over at one point and there was a howler monkey right nearby me, and it was just like, wow, this is where they actually live.

And also it was really interesting to think about the, what a risky place they live in. They, they can't just step anywhere. They put their foot down, and, if it's not on a [00:03:00] branch, it could be a fall. It was just super, super cool to get up there and see what life is like, and the diversity of life in the canopy is not even that well known. A lot of people call it another frontier.

Alexander: Well, and I think as children, some of our first core memories interacting with nature are climbing trees. So what first got you interested in taking you from such childhood experiences to go even further as an adult saying, I want to go way up into some of the tallest trees and better understand what's happening in the canopy?

How did you get pulled into that work? Did you always love climbing trees or was this just a natural segue for you?

Tremaine: Well, that's a funny question because I was not one of those kids who was like climbing every tree I could find. I have two kids now, and they're a little bit like that. I was like kind of a cautious kid, and I think I didn't necessarily think I'd end up in the treetops. I'm a fairly adventurous person. But, when I first started working on this kind of research, I was working with a mentor who said, okay, [00:04:00] so we want to monitor places where animals cross over treetops over linear infrastructure in the tropical forest. So we think what would be best is to collar those animals, like with radio collars.

And that means you need to dart them and they fall down to the ground. And it's pretty risky for the animals and it's difficult work to do. So we were thinking about other methods and we thought maybe we should use camera traps up in the canopy. At the time I was working on a project in Peru, as a Smithsonian postdoc. I went to this training course in Panama with my Peruvian colleague, we learned how to climb up into the canopy. Like I said, something I hadn't necessarily considered before, but what a spectacular experience.

Like I said, it's just a really different world up there in the canopy. And, by doing that, we could then place camera traps up in the treetops where they really hadn't been placed before. Researchers have used camera traps for decades on the ground, [00:05:00] but putting them up in the canopy allowed us to do the same type of monitoring and not have to collar the animals, but to monitor specific locations where we wanted to see if they were crossing. And it turned out to be really effective even though some of the terrestrial camera trappers I met told me, you can't put camera traps up in the canopy. And by then I'd actually already done it. So I said, oh, it's already been successful. And they workedreally the same way, but we were a hundred feet up in the trees.

It was cool to see that it was successful. We had to adapt the mount that the camera's on a little bit. My dad and I worked together to adapt the mount. So we made that mount and then we began to do the monitoring after that.

When we think about diversity up in the canopy, what's been super cool with our research with camera trapping way up in the canopy is that we've detected species that had actually not been known to exist in different areas. I had an experience in Peru where. I had a lot of camera trap photos of a very [00:06:00] small porcupine, and we in fact found that it was not an undescribed species like that was a possibility, but it was actually a species that was 900 kilometers from the area that it had been described in previously. So it was known in northern Peru, but not in Madre de Dios in Southern and Cusco and Southern Peru. So it's a, it was a hairy little dwarf porcupine, extremely cute, tiny little porcupine. And I worked with a team of Indigenous, people in the forest and they also were surprised to see it. I think it's an animal that lives so high in the canopy, that it's not really seen on the ground. That was a super cool finding and really tells you what camera traps can do, what monitoring in new areas can do, and the fact that we really don't know what all is out there, what all we need to be helping to conserve.

Alexander: This is so cool. These are incredible feats of engineering. I wanted to ask, how high off the ground do you get when you're doing this? But you had [00:07:00] mentioned a hundred feet, how high can you get and how long do you have to stay then in the trees?

Tremaine: You can really get extremely high. People climb, uh, you know, redwoods in California. The limiting factor is the slingshot that needs to get you up there. So we use a slingshot that's about six or seven feet tall and then slingshot way, way up into the canopy to get the line over a branch. You first, you shoot like a string that you put over the branch and then you, it's strong string.

So then once you get it on the right branch, you pull up a climbing rope using that same string. So that was actually also another really fun part of the work, in Peru, is working with different team members and a lot of times unexpected people would be really good at using that slingshot, but sometimes it can take many hours to get your rope on the right branch. And then even once you get up there, you might determine that the camera needs to go on a different branch. So you have another small line on your harness that you throw over a different branch and you move over [00:08:00] there and you can go up higher. But, yeah, definitely a hundred feet, sometimes a little bit more than that.

It's a little bit, a little bit scary, but, best not to think too much about how much is resting on that rope. And we do a lot of things to keep it safe. Testing, testing the line, taking good care of the equipment. It's pretty, pretty thrilling. And I was going to say, I didn't do a ton of tree climbing as a kid because I suppose I wasn't like the strongest kid for tree climbing, but tree climbing on a rope, once you have this skill, it's really not that difficult. It could look more difficult than it actually is. So you don't need to have all kinds of upper body strength. You use your legs and you really push on up there.

Alexander: I don't know. It still sounds pretty scary to me. I don't know if I would want to try that, although I probably want you with me for a first go at it.

Tremaine: I dunno!

Alexander: It's so incredible. This work is amazing. There's so much that goes into just journeying into this other world and you were talking a bit about some of the work that you were [00:09:00] pioneering and working on with others on camera traps and monitoring of wildlife up there. But you also have done a lot of work on canopy bridges as a way of connecting a lot of these habitats and these tree canopy habitats.

Could you talk a little bit more about what canopy bridges even are to begin with? Why are they needed and what impacts are happening in the forests to make them necessary?

Tremaine: Yeah, so canopy bridges are, it's a really simple concept actually, and if you walk down the street, this afternoon you'll probably see canopy bridges along the way, and they're really just crossings over what we call linear infrastructure or can be even be gaps in the forest. Species that live in the canopy, especially in the Amazon, so in the neotropics, are very much adapted to life in the treetops because there's been continuous canopy cover in the Amazon for, you know, millenia. So, um, their, their adaptations are for that lifestyle and not for coming down to the ground.

So when [00:10:00] you, when there's a gap in the forest or in, in whatever kind of habitat we're talking about, um, arboreal species have trouble getting from one side to the other. Some arboreal species. So canopy bridge, bridges that gap, by creating a crossing that's at the level of the canopy. So the work that I was doing in Peru, when I was at the Smithsonian involved, actually working with a company that cleared in the Amazon, they cleared a clearing for a pipeline and we worked with them before that clearing was made to identify locations where we thought the canopy would continue to connect in spite of that clearing. And then we labeled those trees and we worked with the people that were clearing with bulldozers and all kind of kinds of equipment to take good care of those tree trunks, so that the connectivity would be maintained when the clearing was finally complete. So sometimes you can see that, like I said, in your community, [00:11:00] if you see that branches have grown over the top of a road and you can see squirrels crossing on them.

But so when we did this, we wanted to see whether animals would like those branches for crossing. And after the pipeline right of way was cleared, we climbed up and put camera traps there to verify whether animals were using them. So those bridges, those canopy bridges were made out of branches. They're just, we, what we call natural canopy bridges. Again, it seems like a super easy solution, but in a lot of places there's a drive to cut that connectivity so that branches don't fall on cars and things like that. But when trees are well cared for, that's not really a danger. So that's what a natural canopy bridge looks like. And our research is showing that seems to be what animals prefer.

But there're also artificial canopy bridge solutions that involve replacing that natural connectivity with things like ropes and cables. So I've also contributed to [00:12:00] research, looking at what designs animals prefer of those artificial canopy bridges. Right now I'm collaborating with a researcher named Fernanda Abra, she's a postdoc at the Smithsonian, and she's testing different designs again in the Amazon to see what animals prefer. And what we're finding is that, if we can combine stability using materials that are very strong like steel cable, but with a little bit more of a natural feel, we braid rope on the outside of it. Then animals can have something that's nice to hold onto. But, it's also very strong because again, just like you don't want branches breaking down into the road, you don't want artificial canopy bridge breaking down in the road.

That, actually in that study in Brazil, they're only something like nine or so species that are using the artificial bridges. So those are the species that are a little bit more brave, they're a little bit more adaptable. You have species with very large brains like capuchin monkeys that will experiment with new stuff, or tamarins, [00:13:00] golden-handed tamarins that really like, um, or they're very driven to cross the road.

They actually have been found crossing on the ground and experienced mortality when crossing on the ground from being hit by vehicles. But now they're beginning to use those crossing structures. They have been shown in some places to reduce mortality on the road because animals no longer are driven to cross on the ground. Instead they, they cross in the canopy.

Alexander: So these are proving to be really successful for most or a lot of mobile canopy dwelling species. Do you see different animal personalities start to come out with how they engage with these artificial bridges?

Tremaine: Yeah, I mean there's a lot of variability and that's why, that's what drove us to say maybe we need to start experimenting because when you look at the anatomy of an arboreal animal and you look at the way they grasp branches, they actually grasp them this way rather than this way. When we climb a ladder, we want to use it this way, but arboreal species grasp this [00:14:00] way. And so we thought maybe we should experiment by giving them just a really nice single line to use, like I said, with the cable in the middle and the braided rope on the outside and see if they'll use that. And in fact, they're showing in our experiment in Brazil, they're showing a preference for that single line. But then you also have species, like howler monkeys and spider monkeys that use their prehensile tail to travel in the canopy.

So I've collaborated with a researcher in Costa Rica who uses very ingenious designs and recycled materials like seat belts from cars to, to create canopy bridges that have two lines so that they can grasp on the bottom and grasp with their tail on the upper line. There's, been a major, problem for howler monkeys in Costa Rica and in other places where they travel on power lines and because they grasp with their tail, it creates a short circuit, and it can be like a major source of mortality for howler monkeys. And I've also collaborated with researchers in Peru [00:15:00] that are also affiliated with WWF-Peru, and they've found spider monkeys crossing canopy bridges for the first time. Again, showing that they need places to grasp with their tails. That's very, it's some really exciting findings that are coming out of these different experiments, that it's not a one size fits all kind of a scenario.

Alexander: On that learning point, I think when either you, yourself are up in the treetop, or through what you see through the camera traps, I think it's so important to have that kind of visibility too. 'Cause those eyes into that world and images, they make everything more real. And once you see something, you believe it so much more. You believe that there's a whole world up in the trees that we normally aren't a part of every day. Did you find that the more you learned and shared this work, that you found new connection with people into the wonder and importance of wildlife and the need to protect them?

Tremaine: Yeah, I felt the super privileged to have been involved in these projects, to have that start at the Smithsonian 15 or so years [00:16:00] ago to be engaged in a project that people can really relate to. I've, had the opportunity to talk to my kids' elementary school classes about it, but then also, I've presented on it at conferences and everyone can understand that an animal that moves in the treetop needs a place to continue to do that. And the camera trap images and the videos really bring that home. And they've been a, an amazing gateway to help people understand conservation problems, to understand how linear infrastructure impacts wildlife, and that we need solutions. And solutions don't need to be extremely complicated, and they don't need to be extremely expensive. It's really cool to think about how we can use these simple solutions to help wildlife.

I can think of one study in Argentina where it was a group of students, I think they were high school students who got together. They saw that the howler monkeys were having, experiencing mortality from a road. So they got together, designed a canopy bridge and installed it, [00:17:00] and monitored it. And they're now finding that arboreal animals are using it. So it can really be a very grassroots solution. At the same time, in places like Japan and the UK, there are canopy bridges, very sturdy, canopy bridges being designed for animals like dormice that are endangered, and they've experienced a lot of habitat fragmentation from linear infrastructure. So these are big substantial canopy bridges that, that are built over highways. So there's a lot happening in the canopy bridge world.

Alexander: I love that, and I think the more that I'm learning from you, the more that I'm really seeing yet again the importance of seeing through others' eyes, whether that's through the camera traps of how animals are living their lives up in the trees, or maybe it's bringing people into your work as a partner to learn about each other's work and feel like you're all part of the same project, to even what you're presented with when you climb a tree and you reach new heights, changing your perspective and vantage point is [00:18:00] so important. And I just want to ask you one final question, building on that theme. What made you want to shift your career from focusing on the treetops to a broader look at sustainable infrastructure?

Tremaine: Yeah. Well, it's been terrific coming to WWF because it's very much focused on changing policy and making sure that the needs of wildlife are incorporated to landscape level planning and to the design of infrastructure and the construction of infrastructure at all stages.

So in our work at WWF, we look not only at arboreal species, like I've described, but we also look at solutions for animals that live on the ground, terrestrial species. That means developing policy for wildlife underpasses and overpasses or developing policy that requires linear infrastructure to avoid really sensitive habitat areas. And I feel like it, it really makes a difference on a large scale. I love being [00:19:00] in the canopy and installing canopy bridges and I hope to continue to do that throughout my career, but it's also very exciting to feel like I've contributed to change in national and even international policy to do better for all sorts of animals across the spectrum, and with these better policies, be better for and safer for wildlife and safer for people. Because after all, we know that hitting wildlife on the road is dangerous for everyone involved.

Alexander: I could honestly listen to your stories for hours Tremie, you have had some pretty incredible experiences. I would love to find my way to the forest one day with you and get some climbing tips from you.

Thank you so much for joining Wildlife Café. It has been an absolute pleasure.

Tremaine: Thank you so much, Alexander. It's been wonderful to join you.