Tooth and Claw: Harpy Eagles

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1:08Adam Hart:You're listening to Discovery from the BBC World Service. I'm Adam Hart and this is Tooth and Claw, the series where I explore our complex and challenging relationships with Earth's greatest predators through the people who have spent their lives studying, protecting and at times narrowly escaping them.

1:30Adam Hart:Today's predator is named after a mythical beast. A crown of feathers atop its head, this regal-looking raptor dominates the canopy of the rainforest across much of South and Central America. With huge talons and strong legs, it's widely considered to be the most powerful bird of prey. Yes, we're talking about the harpy eagle. And joining us to discuss this apex predator are Dr. Elina Aguia-Silva, a biologist and associate research scientist at the National Institute for Amazonian Research in Manaus, Brazil, and a member of Project Harpiegel, and Dr. Eduardo Alvarez, who founded a non-profit organisation called EarthMatters.org to concentrate on the study and conservation of harpiegles and to preserve their rainforest habitat.

2:12Adam Hart:Now, harpiegles are a very rare sighting, even in the areas where they're found in South and Central America, so I expect the vast majority of our audience will not have seen one. Eduardo, what do they actually look like? The striking thing about Harp Eagles is they're very large, unusually large when you see one. And especially when you look at the legs, if you're able to see the claws on the legs, they look huge. It's black on the back and white on the front with a black band across the chest. And the really striking thing on a Harp Eagle head would be a couple of feathers that stick up over the head.

2:51when he's interested in something or keenly trying to keep any potential aggressor away, these feathers come up and they almost look like two horns. Other than that, there is a group of feathers around the head and the neck that make it look like a diurnal owl.

3:13Adam Hart:Do they also use the feathers around their face and necks to help them catch sound waves like owls do? Yes, they have the ruff of feathers all around their neck and they can turn their head all the way around almost. And I think they use that to catch the sounds like an owl would do to be able to locate their prey. But it's a very imposing creature, wingspan up to two meters, seven feet, and the largest claws on any bird or prey. Yes, I've had the great pleasure of seeing one in captivity actually in Panama in a captive breeding center. And it was quite an incredible sight. The talons stick three or four of my fingers put together quite easily.

3:54I've talked to hunters that had shot an eagle. And one of the reasons why they would shoot a harpy eagle is they might bump into one on a trail and the eagle is sitting on a fallen log with prey on its talons. and it would see this person coming towards them and these feathers would pop up and they would look at you and it's the people think they're looking at the devil or they're looking at a witch with these horns and they just blow it away. And it's a misfortune that they're confusing the eagle with an evil creature.

4:33Adam Hart:And Elena, we have a nice idea now of what this very imposing bird looks like, but where would you actually find one? The Harpy Eagle is found in the tropical lowland rainforests from Central and South America, and ranging from southern Mexico, historically, through much of the Amazon basin, including caltron search Brazil, where I'm from, Venezuela, Peru, Colombia, Ecuador, and Guyana, down to northeast Argentina, and in Panama and Central America. The geographic distribution includes the Amazon, the Atlantic Forest and the Forests of Central America. So these birds are birds of forest habitats.

5:18Adam Hart:Why is that? Harpy eagles are true forest specialists, where they use their powerful wings and incredible agility to hunt among the branches. The rainforests provide them with shelter, prey and nesting sites, all crucial for their survival. Then, harpy eagles typically select the tallest trees, known as emergent trees, to build the large nests, which are positioned on average at a height of 45 metres, very high. The nests are large structure, on average 2 metres in diameter. A large eagle needs a large nest. Now, Eduardo, let's talk about the harpy eagle's name. Where does that come from? The harpy is a mythological, I guess, hybrid creature in the Greek mythology, which is half woman and half bird.

6:17Very frightful flying creatures that had hook, beaks and claws and would snatch people away. So the name harpy means a snatcher.

6:27Adam Hart:That's obviously a European mythology. Is there a folklore and mythology about these birds where they're actually found? Absolutely. The harpy is well known to the indigenous people. It's revered by most of those groups in their cultures in the Americas in general. It's considered to be a sacred spirit animal. It's highly respected by the natives. You can find it in their art. You can find it in their carvings. They actually, if you look on the molas, which are made by the Kuna people in Panama, a quite famous tapestry. There are all kinds of eagles in there. And for example, the Waurani tribe in the Amazon of Ecuador, they consider themselves descendants of the harpy.

7:17It's a very sacred symbol of power and protection. And actually, the Waurani has been featured in some encyclopedias and different publications because they captured juvenile harpy eagles, and they keep them in their small village as a sentinel bird that warns them of intruders that might come and attack their village. So they take care of them, and I think they eventually release them back into the rainforest. Another experience that we had was in Venezuela, in the Cauda River, there was a group of local people, local Indians working at a tourist facility in an island in the river. And a harpy showed up and he actually was attacking the pet macaws that they had in the island.

8:11And one of the managers for the island hit the eagle with a pole and broke its wing. And as soon as that happened, all of the indigenous people that were there, they were or Makiritare Indians, I believe. They all started crying and screaming, and they got on their canoes and left because they believed if that harpy died, one of them was also going to die. And they wouldn't come back until these people somehow disposed of the eagle. And we found out about it, and we made a trip over there and rescued the eagle. So most of these people are very concerned about keeping the eagles in the rainforest and not hurting them.

8:56Adam Hart:So we've started to get a sense of what harpy eagles look like, where they're found and some of the folklore behind them, but this is tooth and claw, so we need to find out what they actually eat. And Elena, your master's degree was looking into what harpies eat in nature. So what do they prey on? Harpy eagles are top predators and mainly hunting animals that live in the trees, especially sloths, monkeys and porcupines. The diet often includes species such as holly mochins, capuchins, monkeys and both, two toads and three toadslots, depending on what is available in their territory. Harpy eagles also occasionally prey on birds and reptiles, for example, macaws and iguanas.

9:43So far, over 600 species of animals have been identified in the Harpy Eagle's diet across its range, mostly of them mammals, with a lower proportion of birds and reptiles. And this variety in the diet shows how important Harpy Eagle are in helping to keep tropical forest ecosystem health and balance. However, in some tretenant regions of the Amazon, with deforestation is intensively acting in the harpy eagle habitats, there have been reports of the harpy eagle preying on domestic animals such as young goats, lambs, chickens and domestic kittens. But the main prey, even in its deforest regions, are the wild animals, sloths, monkeys, or other arboreal animals.

10:40Adam Hart:So harpy eagles mainly prefer to feast on arboreal mammals, those that live in trees, but deforestation has led them into occasionally eating some ground-dwelling domestic animals. Eduardo, what have your observations been? Elena said that they actually would take baby goats. When you open a rainforest and you bring new animals in there, there is a shift on prey base. And we have seen eagles on the border forest nesting meters from the place where they open up the rainforest. And they do a total shift from monkeys and sluts to almost 100 % armadillos. because there is an explosion of armadillo population in these open areas where they have a lot of food available on the soil.

11:29So the harpies like something easy, like an armadillo, walking around half blind, and they can just come and get it really easily.

11:38Adam Hart:And Elena, am I right in thinking that harpy eagles have shorter wings than other eagles? Does this help them to navigate through the dense rainforest? Their wings are short and broad, which might seem unusual for such a large bird. But it's exactly what they need to move through dense branches and leaves high up in the forest. And this wing shape allows them to flap and navigate in tight spaces, helping them carry heavy prey like monkeys and slugs. A different design for agility and manoeuvrability. This adaptation allows them to launch silent, powerful ambush in the forest. And Elena, are harpy eagles a credible threat to humans?

12:22Not at all. Some individuals are curious and confident, others are more discreet, but not aggressive toward humans unless provoked or defending an ex or an offspring. In fact, the humans are the real threat to them, through deforestation, hunting and disturbance. Here in Brazil, we have been studying these species for 20, 80 years, and none of our team members have ever been attacked by a Harpy Eagle. September's always busy. Whole Foods Market can help. Their September Stock Up event makes it easy to load your pantry and freezer with flavorful, nourishing food. Even better, there are hundreds of sales.

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13:54Adam Hart:You're listening to Discovery from the BBC World Service. I'm Adam Hart and this is Tooth & Claw. We're talking about the apex predator of the rainforest canopy, the harpy eagle. And joining us are Harpy Eagle experts, Dr. Elena Aguia-Silva and Dr. Eduardo Alvarez. So far, we've learned a lot about the Harpy Eagle itself, but I'm keen to find out a bit more about you both and your work. Elena, you monitor Harpy Eagle nests. How many chicks are there usually in the nest and how long do they stay there? Harpy Eagle typically rises only one chick every two to three years, a very low reproductive rate.

14:30The chick remained in the nest for around five to six months before it started flying. Even after fledging, the young eagle continued to really its parents for food and learning to hunt for up to 18 to 25 months. It's an incredible long and slow process.

14:52Adam Hart:And how do you access the nest? How do you study them? Do you have to climb up 45 metres into the canopy to get to them? Yes, and it's one of the most accelerating and humbling experiences in field biology. We use ropes and climbing harnesses, similar to ones used in rock climbing, to safely ascend up to 45 meters. It takes training, caution and teamwork. But the reward isn't forgettable. Standing beside the nest of the largest eagle in the Americas, knowing that the data you're collecting may help ensure its survival in the wild. It's amazing. Do you remember when you saw your first harpy eagle in the wild and how it made you feel?

15:36Whoa! I'll never forget that day. The first harpy eagle I ever saw was in the Amazon rainforest back in 2005. It was a juvenile, nearly a year old, pershid rye in its nesting tree calmly watching us from above. That was my first time at a Harpy Eagle Waging site, and I was there with my supervisor, Dr. Tania Senayoti, to monitor the nest as part of my Master's degree research. We were collecting prairie men from the forest floor below the nest and took a few photographs. The bird's sheer size and powerful presence were unforgettable.

16:22Adam Hart:So that was the first time, but can you remember the closest you've ever been to an adult harpy eagle? Fortunately, and to the envy of many, I've had the privilege of being close to many harpy eagles, adults, juveniles and athletes. Along these years, I'm studying these species at different moments. But one of the times was in 2022, when I had to hold the harpy eagle in my arms. Literally, I gave the eagle a hug. My heart was beating faster than usual. It was a powerful moment. I feel the force of this species, very, very powerful. And when handling a happy eagle to collect data structures, body mass, wingspan, a blood sample for health and genetic studies, we always work as a team of at least four people.

17:18One to hold the wings, one for the talons, another for the head, and a fourth to take the measurements. That day, for the first time, I was the one responsible for securing the eagle in my arms. And it was absolutely powerful.

17:33Adam Hart:and eduardo your journey with harp eagles started back in venezuela what first drew you to them i was doing wildlife inventories for a hydroelectric dam in the carony river in southern venezuela some local people told me about these very large eagles when i look in the literature and then the you know the venezuelan bird guide it was a very small entry hardly anything was known. It was basically a cryptic species only known in encyclopedias. This was in the early 80s. As I started doing surveys and questioning local people, I realized that they encountered these birds fairly often in their lifetime, and quite a few of them had shot harpy eagles.

18:24So I got concerned that such a large animal and so rare to found was quite often shot by local people. And then in one of my field trips, I found a nest and the nest was empty, but the eagle showed up and perched on the tree and spent the night there. I watched it until it got dark and in the morning I saw it again and then it flew away and it seemed to like be looking after its nest even though it was not the active part of the breeding cycle. I was captivated by it's uh you know it's a majestic bird like all the eagles and it didn't seem to have a care in the world about any other potential enemies it was just quietly taking in her local kingdom I guess and I was quite taken by it.

19:18Then later on, when I was in the camp near the dam, somebody called me and said, look, I shot this large bird. I want to show it to you. And they came to me and there was a juvenile harpy eagle, full size, that they had shot. It was still alive, but it died. And I was really impressed by the fact that they shot this bird just a few kilometers away from the dam construction site, where we had weekly dynamite explosions, all kinds of building equipment and everything making noise. And I realized there were still harpies in a nearby forest. So I became really interested in these birds and started collecting all the information I could.

20:05And eventually, by the end of the 80s, I decided I was going to dedicate the rest of my professional life to study these birds. So I quit my job and came to the University of Florida to attempt a PhD, a doctorate degree on harpy eagles, which was crazy given the fact that there was not even one nest reported for the country. But I figure, as opposed to like the typical approach of biologists that they go and they spend a year looking I spend my first few field trips talking to local people and finding the local knowledge and I was very successful finding nests in the logging concessions.

20:53Adam Hart:So you've made this decision to quit your job and dedicate yourself to the study of harp eagles can you tell us a bit about your work actually out there in the field? Eventually when we found our first active nest and we saw how the juvenile have stayed in the nest for such a long time, a whole year after they start flying. I became interested, like, I have to trap these animals. So I basically invented a noose trap that we could raise up with a rope up into the nest tree and get the bird to come in there to feed on a piece of meat and pull the noose on its leg and bring it down. And, you know, we got it to where in about 20 minutes, we could process all the measurements, get all the information, put a band on the leg, and put a transmitter on the back of the eagle.

21:40Well, the first two eagles that I banded and tagged in Venezuela were both shot within a year of then dispersing from the nest. And that was like proof right there that there is a huge problem with eagles being shot. So then we decided we need to do more. We need to find more mess. We need to get the local people to protect them. We need to ban every eagle we can find so we can figure out where do they go when they disperse and are they successful eventually. And we're getting there. We have 35 years of information now. We've been able to find over 100 nests.

22:28Adam Hart:It's obviously pretty remote out there in the rainforest and difficult to find and track these animals. What kind of technology can you use? After I found the first couple of nests, I became aware because a local friend told me that he bought this gadget, I guess, very expensive$3 ,000 GPS. It was the first civilian-approved GPS from the United States. a Magellan Nav 1000. It's a museum piece now. And he says, would you mind figuring out the manual and how to use it? And then you train me. So I took this thing on the road and I immediately realized this is going to be the key to my work because I am going to geo-reference and map everywhere I go, every nest I find, every sighting of eagles.

23:19And we've been doing that for 35 years. and one of the key things for me was like how are these eagles feeding in the forest how do they space themselves out is it a regular distribution is the forest saturated with nests and to find the answer to that you have to have clear measurements between active nests and the first time i went to guiana with neil reddick i asked him to rent one of these units and we got the first measurement of distance between two active harpy nests. And, you know, it was within a few kilometers. So then I started measuring all the nests in Venezuela. I expanded my project to Panama, and I started also measuring distance between nests over there and mapping every trail and every axis to a nest.

24:12As you put this together, you develop a picture where you say, okay, I have a nest here, and there's one seven kilometers away over here, and I haven't found anything on this area. So then when you look in there, you can actually predict you're going to find a nest in there because they're regularly distributed. Interestingly enough, the distance in Venezuela and the Matacafore is about seven kilometers, and in Panama is half of that. And it makes you wonder what's the difference well it's the topography it's got mountains so every creek that comes down the mountain it's like a specific habitat at the bottom where you can have a nest and then the next creek is three miles away let's say and there's going to be another nest in there predictably also there might be a higher abundance of prey there's a lot of primates in that forest you see them everywhere so the eagle doesn't need to go that far to find its food so gps has been like a deal breaker for us and we've evolved from satellite transmitters that were not so reliable to transmitters we can put on the eagles now that have gps chips so you get real like very precise location within a few meters or where the eagle is moving so you were one of the early

25:36Adam Hart:pioneers of this technology. Yes, we were probably the pioneer for biological applications of GPS for studying animals and finding out where they move and what they do. Before that, GPS was for guiding missiles and for navigation. And Elena, it's widely known that deforestation is a huge threat to the species that live in rainforests, but how much impact is it having on harpy eagles and why is it so important that we protect these birds? As rainforests are destroyed for logging, farming and vast soil monocultures, these top predators lose its home. In some regions this species is already gone as in some countries of Central America with only one chick every two to three years and have dependence on large forest areas it cannot recover quickly from habitat loss.

26:32Every fallen tree perches these magnificent birds closer to extinction. Unfortunately, deforestation is devastating for harpy eagles. They need vast, continuous forests to hunt and raise their young. When forests are cleared, they lose prey, nests, and safety. Harpy eagles are an indicator of ecosystem health. Protected them means preserving biodiversity, climate, stability and the future of the rainforest itself. And they need our help for more than ever. In addition to support numerous traditional human communities that use the resources from the rainforests, these forests play a vital role in ecological process and in regulating the global climate, particularly through the water cycle.

27:28Despite the threatening scenario for Harpy Eagle, there is still hope. In remote corners of the Amazon and in fragments of the Atlantic Fork, this majestic bird continues to soar. Here in Brazil, conservacionistas, researchers and local communities are working together to protect nests, monitor individuals, rehabilitate rescued individuals and restore forest habitats. What means saving the harpy eagle means protecting an entire ecosystem and ensure this natural heritage endure for future generations.

28:11Adam Hart:You've been listening to Tooth and Claw with harpy eagle experts Dr. Elena Aguia-Silva and Dr. Eduardo Alvarez. I'm Adam Hart and the producer was Jonathan Blackwell. and you can listen to previous episodes by searching BBC Discovery Tooth & Claw.