Chameleon Eagle
How do you study a bird that nobody can find? In September of 1992, this was the question that faced Lily-Arison Rene de Roland, a graduate student from the north of Madagascar. Lily-Arison (he goes by Lily) had attended university hoping to become a pharmacologist but a few months earlier the university’s pharmacology professor—and Lily’s one hope of advancing into a professional career in the field—had rejected his PhD application. Despite Lily’s strong grades, the professor wanted a student who spoke English and Lily, fluent in both French and Malagasy, did not qualify. Rather than leave academia, however, Lily had decided to apply for a different PhD, one he saw being advertised by the Peregrine Fund, a US-based conservation organization that works on endangered birds of prey. Lily had no experience with wildlife or birds of prey, but the project seemed intriguing and the Peregrine Fund promised full financial support and had no English language requirement. His application was accepted, and that September Lily began research with the Peregrine Fund. On paper, the project was straightforward. The Peregrine Fund wanted Lily to find and study Eutriorchis astur, the Madagascar Serpent Eagle.
First described in 1875, ten Madagascar Serpent eagles were collected by European ornithologists in the years between 1875 and 1930, and then the bird suddenly and inexplicably disappeared. By the time Olivier Langrand published his Guide to the Birds of Madagascar in 1990, no one had definitely seen a Madagascar Serpent Eagle in over sixty years. Had it gone extinct? It seemed unlikely. As Langrand put it: “hope of finding the Madagascar serpent-eagle is justified by the fact that the sites where it was captured in the past are still intact.” In other words, the forest was still there, so theoretically the eagle should be as well. It was just a matter of figuring out how to find it.
Large eagles do not have a tendency to go missing. Beetles, spiders, amphibians, even snakes and the occasional species of small bird can be unrecorded by scientists for years or even decades. But eagles are big, they are usually conspicuous, and they have a predisposition for attracting the attention of both international researchers and local people. In fact, the Madagascar Serpent Eagle’s situation was unique. In the early 1990s, this was the only eagle that no one seemed able to find. In essence, it was the rarest eagle in the world. So even if Lily’s project was straightforward, it was not going to be easy.
Usually when you go looking for a particular species of bird you rely on information about its habitat, behavior, and vocalizations to find it. These details can be so characteristic that they are often reflected in the names of the birds themselves: Bearded Reedlings inhabit reedbeds, Wood Warblers like woodlands, wagtails unceasingly dip their tails up and down, and Common Cuckoos loudly sing a two-noted approximation of “cuck-oo.” In tropical forests, vocalizations are the most significant of these details when it comes to finding a species. Almost all birds communicate by calls and songs and for species that inhabit the dense vegetation of the tropical rainforest these auditory signals are especially important. Learn the sounds that a bird makes, and you can tap its communication lines and find it.
When Lily set out to study the Madagascar Serpent Eagle, however, all of these details were missing. Aside from what appeared to be a general preference for rainforest, no one knew anything about the serpent eagle’s habitat, how it spent its time, or what it ate. Most importantly, no one knew what it sounded like. As a result, trying to find it was a bit like looking for the proverbial needle-in-a-haystack. Only in this case the needle is watching you and silently moves out of the way whenever you get close to it.
I’m reflecting on this challenge as I walk behind Moise, the Peregrine Fund’s lead field technician, through the forest near Bemanevika in northern Madagscar. Like many Malagasy, Moise has only a single name, and he has been working with Lily for nearly twenty years. Bemanevika is a newly designated protected area and in addition to Moise, I’m here with my friend Dale Wright, a South African ornithologist and conservationist, and an international team of field biologists with expertise on birds, spiders, moths, and reptiles and amphibians. Together we are planning to do one of the first biological inventories of some of the lesser-known biodiversity in Bemanevika and an adjacent protected area called Mahimborondro. But before we begin our survey work, we are all eager to see a serpent eagle. To be honest, that alone would have made the multi-day journey to Bemanevika more than worth it for most of us. Lily himself is also with us, but this morning he is waiting back on the main trail. He has seen many Madagascar Serpent Eagles by this point and doesn't feel the need to scramble through the forest with us today.
The morning is cool and overcast, and mist sits heavily amongst the trees giving an eerie feel to the landscape. Every few minutes, Moise stops and unfolds a metal radio antenna. He lifts a receiver up to his ear and it pings softly as he holds out the antenna, pausing it at compass points to listen. It all sounds the same to me, but Moise has done this before. This way, he gestures, and we quickly follow down yet another side trail winding deeper into the forest.
Finding a serpent eagle today should be easy. We are following a young bird that was fitted with a radio-transmitter a few months earlier so that the Peregrine Fund researchers can learn about its movements and behavior. Every time the eagle moves, we roughly know where it is and how far away. But even with the game rigged in our favor, this feels like a challenge. Wet leaves slap against my face, vines armored with spines wrap around my ankles and a seemingly endless stream of land leeches march up my pant legs. Every few minutes, Moise pauses, unfolds the transmitter, and adjusts our direction. At one point the pinging of the transmitter seems to be directly above us. We squint into the misty canopy, quietly stepping from one side to another hoping to get a better angle. And then the pinging moves, and we’re doubling back the way we came. It has been nearly an hour, and I’ve seen nothing.
Lily began looking for the Madagascar Serpent Eagle on the Masoala peninsula, home to one of Madagascar’s largest remaining tracts of lowland rainforest. To find an eagle that no one could see, Lily decided to rely on using mist-nets. Usually between six and twelve meters long, these are long nets constructed with nearly see-through thread. They are designed to catch birds without injuring them and are one of the primarily tools of ornithological field researchers around the world. I have worked frequently with mist-nets in myself, and while it is always rewarding to be able to have a bird in the hand, I find them exhausting.
To be effective, mist-nets need to be opened at dawn, checked every half hour, and quickly closed if it looks like it might rain or as it starts to get dark. In the tropical forest, they constantly get snagged on twigs and vines. Moths, beetles, and leaves drop into them and become impossibly entangled, and you have to be always vigilant, checking to make sure that birds don't get stuck for too long, and hurrying to shut the nets if the weather turns, as it seems to almost always do in tropical forests. With a team of researchers working together, the most nets I have put up at once is thirty. We set and monitored them in the forest for three weeks. When we returned to the city at the conclusion of the fieldwork, I walked into my hotel room, sat down on the bed, and fell asleep fully-dressed, feet on the floor, muddy boots still on.
Lily and his team set up one hundred and fifty mist-nets on Masoala. In January 1994, nearly five hundred days after they started fieldwork, they had not seen or caught a single serpent eagle. But they were still there. Opening, checking, cleaning, closing, one hundred and fifty mist-nets.
At this point, I want to interject to say that if it had been my job to rediscover the Madagascar Serpent Eagle, I would have done it very differently. Even though forest eagles will chase prey down to the ground, they typically pass most of their time higher in the trees, and the odds of catching one in a mist-net are low. Instead, I imagine I would have hired a small field team and spent days quietly walking through the forest, moving between locations and trying to cover as much ground as possible in hopes of encountering an eagle face-to-face. Probably I would have combined this with interviewing local villagers, but the eagle’s apparent affiliation for the most remote forests and its superficial similarity to other Malagasy raptor species would have made this challenging. Mine would have been strategy designed to be as fast and, by hiring only a few people, as economical as possible.
Standing in the forest near Bemanevika, I cannot help but wonder if, consciously or not, my approach to finding a serpent eagle somehow reflects an underlying cultural framework of mine. Time and people are the most valuable of resources in my world and should always be maximized as much as possible. When planning this expedition, Dale and I had fretted over timelines. How many days would it take us to travel from Antsohihy to Bemanevika? What time would we arrive at different points along the way? When not worrying about travel times, we had turned ourselves in circles planning the porters we me might need for different stages of the journey and contemplating how many kilos we could personally carry to offset the costs of hiring.
Lily seemed much less concerned with these. Maybe the trip to Bemanevika would take one day, probably two, maybe three. Probably we would arrive before dark, but maybe after dark. When Dale and I had settled on hiring twelve porters to bring us in and out, Lily considered our budget and politely revised it. For a similar price, we could hire twenty-five porters and they could stay with us the entire time. In rural Madagascar both time and manpower are almost unfathomably inexpensive. In way that perhaps only a Malagasy researcher could plan, Lily’s strategy to find a serpent eagle took full advantage of these. It worked. On January 14, 1994—Lily remembers the exact date without hesitation—the first confirmed living Madagascar Serpent Eagle in over sixty years was lying in one of Lily’s mist-nets on the Masoala peninsula.
I am trying to imagine the feelings of overpowering relief and ecstatic joy that must have accompanied this moment of discovery. Maybe there was dancing, screams of joy. But Lily, true to his personality, is more understated. “Yes, I was very happy,” he says with a chuckle. In this case, one eagle was enough to begin to piece together the puzzle of how to find this bird. Lily and his team fitted the eagle with a radio transmitter, and just as we are doing today, started following it through the forest. A few days later they made the first recordings of its call, an odd croak that sounds so frog-like it was overlooked as amphibian by previous ornithologists. Within a year they had found the first nest of a Madagascar Serpent Eagle to be described by scientists.
As Lily and his team began following that first serpent eagle, the reasons that it had been so difficult to find became clear. First of all, it was shy. If it saw you before you saw it, as inevitably would happen, it would quickly and quietly slip away. Second, it only vocalized occasionally and, when it did, it sounded like a frog. Third, unlike most eagle species which often soar conspicuously over the forest, the serpent eagle almost never left the canopy, instead preferring to hunt quietly amongst the foliage or even drop down to walk on the forest floor. Along with these came a discovery that I find especially fun. The serpent eagle isn’t actually a serpent eagle at all. It almost never eats snakes. In fact, the majority of its diet is composed of chameleons.
Chameleon Eagle seems an appropriate name for a species so adept at making itself invisible. After an hour in the forest tracking the radio-tagged eagle, all I’ve seen is a couple of brief silhouettes and a shadow moving through the trees. And then suddenly, Moise points and urgently gestures us over. I peer through a window in the leaves and there it is, muted wood-brown colors, a hefty chameleon-killing bill and a gleaming golden eye staring back at us through the leaves.
Sometimes people ask me: how do you feel when you see a bird? What makes it exciting? Staring through the misty tree tops, my boots and pants soaked from the brush of wet leaves, leeches crawling up my legs, and looking at this nearly invisible eagle with its neatly fitted radio transmitter, I can’t help but feel that I’m admiring a masterpiece of human endeavor and effort.
Moise is watching us we breathlessly pull out cameras and binoculars and mutter excitedly to each other. When the eagle leans forward and silently drifts deeper into the forest, he gives us an expectant look. Satisfied? We nod happily, goofy grins of relief at our own excitement to see this near mythical creature, and he folds up the metal arms of the radio transmitter and leads us back towards the trail.