“HARPY EAGLES MAINLY HUNT BY MAKING SHORT FLIGHTS FROM ONE TREE TO ANOTHER.”
Seeing a harpy eagle nest is a Holy Grail for birdwatchers. Jonathan Elphick strikes gold in Panama, a hotspot for the world’s most powerful raptor.
Carlos turns and grins. “I think we’re finally going to see the adult eagle this morning,” he says. “Are you excited?” As our fourwheel-drive bumps down a rainforest track towards the Pan-American Highway, there is a resounding chorus of “You bet!” The day before we had made the long journey to a recently discovered harpy eagle nest. Though we were thrilled by the single huge fluffy white chick as it peeked over the edge of its eyrie, it was disappointing not to spot a mighty adult as well.
Since the chick is already about six weeks old, its parents will now be bringing back food – mostly monkeys and sloths – rather infrequently. There is still a good chance of a sighting, however. Any encounter with a harpy eagle – a species that regularly features near the top of ‘birds-to-see-before-you-die’ lists – is a red-letter day. We’re keen to try our luck again.
Harpy eagles breed only once every two or three years, one of the longest reproductive periods of any raptor. While pairs may nest again in the same tree, there is no guarantee: they might move elsewhere for subsequent nesting attempts. So whenever an easily observable active nest is found, word spreads like wildfire among rangers and guides and then further afield, and lodges start filling up with eager birders from all over the world.
Celebrated as Panama’s national bird, the harpy eagle occurs in greater numbers here than anywhere else in Central America. Measured by confirmed active nests, the country’s harpy population is third-largest in the species’ entire range, from southern Mexico south to north-east Argentina. Only Venezuela and Brazil have more harpies. But Panama hosts the highest density, with 800 or more breeding pairs by some estimates. Most are in the Darién, the easternmost province.
The harpy eagle is classified by the IUCN as Near Threatened, though this label is somewhat misleading because in many regions it is rare and declining. The Global Raptor Information Network prefers to class the species as Critically Endangered in Mexico and Central America, and as Vulnerable in South America. Deforestation is an important factor, but the main threat is persecution. Eagles are killed for trophies, because they are wrongly seen as a threat to chickens, pigs and other livestock, and by some native Americans for their magnificent crest and wing feathers, used to make arrowheads and head-dresses.
Why Panama has a relatively healthy population of harpies is unclear, but it may be due to abundance of prey. In South America there are more raptor species and mammalian predators – including humans – competing for food. Also, the Emberá and Wounaan tribes native to the Darién tend to practise low-level subsistence hunting (which does not include the taking of sloths) and small-scale shifting cultivation, neither of which appears to pose any threats to the eagles.
On the second day of our quest, I join guide Carlos Bethancourt and wildlife photographer David Tipling for a bleary-eyed pre-dawn breakfast. Our base is the newly opened Canopy Camp, some 50km from the great expanse of remote rainforest covering much of the Darién, where our target nest lies.
We drive along an increasingly potholed road for an hour, before reaching the small town of Yaviza. At this point the Pan-American Highway, which connects Alaska and the southern tip of South America, peters out for a substantial distance. Here we enter the famous Darién Gap – a near-pristine world of rainforest and swamp extending for 160km, well into northern Colombia.
It is still dark as the Panamanian border police check us out. Then we board a dugout canoe with an outboard motor and begin speeding along the Chucunaque River. As dawn breaks, and mantled howler monkeys proclaim their presence from the treetops with amazingly loud roars, we at last arrive at the settler village of El Real. We climb into a pick-up truck for the short drive to the headquarters of Darién National Park, where we are joined by two park rangers. Finally, hearts in mouths, we walk a trail through the rainforest to the harpy eyrie.
A DREAM COME TRUE
Gazing up at the nest far above, we do not have long to wait. A grey-plumaged adult suddenly appears, every bit as spectacular as I had hoped. It lands near the nest, its enormous rounded wings spread wide. A lifetime dream for many birders has, for our small party, come true.
Though not quite the largest bird of prey – that title belongs to the condors – the harpy eagle is arguably the most powerful. It measures around 0.9–1m from meat-cleaver beak to tail. The wings, which span up to
THE HARPY EAGLE IS A SPECIES THAT FEATURES NEAR THE TOP OF ‘BIRDS-TOSEE-BEFORE-YOU-DIE’ LISTS.
2m, are relatively short for the eagle’s size, but combine with a long tail to give this mighty bird – like a giant sparrowhawk – great manoeuvrability in flight. The tail acts like a rudder as it steers through the dense forest. As with sparrowhawks, females are considerably larger than their mates – at a maximum of 9kg, they weigh up to twice as much.
Harpies hunt mainly by making short flights from one tree to another, pausing at each look-out to locate unwary sloths and monkeys, their chief prey. The dark interior of the forest renders hearing more important than vision. These eagles have a large circular facial disc like that of owls and harriers, which directs sound into the ears and enhances hearing in a similar way to cupping your ears with your hands.
Such hefty prey requires some heavy lifting. Harpies’ immensely thick legs and feet are powerful enough to rip sloths and monkeys from branches. The talons are the largest of any raptor, the sabre-like hind claw being up to 7cm long. A big female harpy can fly off clutching a male howler monkey or adult brown-throated sloth weighing almost as much as she does. Even so, many hunting attempts will end in failure.
Harpies also prey on other arboreal mammals, such as kinkajous, opossums and olingos, as well as iguanas and large birds such as macaws. Very occasionally they may take the odd ground-dwelling animal, such as a young peccary, armadillo or snake.
RICHNESS OF ANIMAL LIFE
Seeing this stunning predator may have been the high spot of my trip – literally, as the nest was over 30m above the forest floor – but there was so much else to marvel at. Panama is phenomenally rich in wildlife for a compact country slightly smaller than Scotland. It hosts 1,000 species of bird (about 100 more than have been recorded in the whole of Europe) and over 10,000 plant species, including some 1,200 orchids and 1,500 trees. New species are being discovered every year.
The harpy eagle seems an appropriate symbol of all this diversity – its domain, the rainforest canopy, is the richest part of the richest land habitat on Earth. Researchers estimate that 60–90 per cent of rainforest life is found mainly or exclusively in this sunlit layer, which typically soars 30–45m above ground level. In the Darién, the rainforest canopy is the home of the aforementioned monkeys, sloths and kinkajous, not to mention toucans, parrots, trogons, tanagers and a myriad other colourful birds, as well as many species of frog, lizard, bat and countless invertebrates, especially ants.
By contrast, shade cast by the dense umbrella of the canopy makes the forest interior a dark environment, with as little as five per cent of sunlight filtering down to the lower layers – the understorey and shrub layer. The forest floor receives even less light: typically just two per cent. This is why so little vegetation grows there. Shallow soils mean that trees are often toppled by storms. A big tree crashing down creates an open area that allows light to break in, bringing new opportunities for trees, shrubs and vines to create a jungle of vegetation in a short time.
One particular rainforest feature with which the harpy eagle is closely associated is the presence of extra-tall trees reaching 40–60m that tower above the canopy.
THE HARPY EAGLE SEEMS AN APPROPRIATE SYMBOL OF DIVERSITY. ITS DOMAIN IS THE RICHEST PART OF THE RICHEST LAND HABITAT ON EARTH.
Known as emergent trees, these form what is sometimes called the ‘overstorey’. A common example in the Darién is the cuipo, which has a massive pale grey trunk that bulges at the base.e. This is one of the trees most favoured by eagles for r their nest.
Pairs of harpy eagles mate fo or life and share the task of building the impressive stick structure, often wedged in a large fork, ad dding green leaves and seed pods to the shallow cu up. Although no courtship rituals are known , the male and female have been observed to c call softly to one another and rub their powerful l bills together while nest-building, presumabl ly helping to reinforce the pair bond.
Female harpies lay two eggs, butb are not known to rear more than n one chick, failing to incubate the second egg (should both eggs hatch, the younger chick wi ill likely fail to compete with its sibl ling). The incubation period is about eighte weeks. The youngster, which has white down,d generally fledges at between six and seven months of age, but even after that length of time e may still beg for food from its parents. It will beb protected by them for a further three or four months.m
The immature eagle goes throughh a sequence of plumages and will remain within 100m or so of the nest for at least 15 months – and in the same general area for up to 30 months. Observations of captive birds indicate that females may not breed until they are five years old, and males at some stage before they are nnine. Should an eagle evade disease and injury, and peersecution by humans, it stands a chance of surv viving 25 or even 35 years. Indigenous Emberá communities in the Darién are using their valuable knowledge of the forest to help locate harpy nests, giving a boost to lodges like the three in the Canopy ‘ffamily’, and to tourism in Panama in general. The T Emberá in turn make money from taking vi sitors in dugout canoes and selling handicrafts. By thhese means they can afford to reject any finan ncial incentives offered by loggers, and thus maint tain their respect for the forest and its wildlife. Wat tching the eagle nest with Carlos and David, I can’t he elp wondering what fate has in store for its spectacul ar young inhabitant. Species like harpy eagles, that repro oduce so slowly, can be extremely vulnerable to changes iin their environment. But I take heart from the fact that ecotourism e is giving the forest in this corner of Panama a much more secure future.