Harpy eagles are huge. Females are larger than males, which is a common pattern in birds and other egg-laying animals including reptiles, fish and insects. An average-sized female might weigh in at around 9kg (20lb), although a captive female named Jezebel was over 12kg (26lb). They can stand more than 1m (3ft 3in) tall and have a wingspan in excess of 2m (6ft 7in).
If, like me, you find it hard to picture a bird from a series of dimensions then let me tell you about the first—and indeed only—time I saw a living harpy eagle.
I was a Fellow for a few months at the Smithsonian Tropical Research Institute in Panama, based in the tropical forests around the Panama Canal. Keen to see a harpy eagle, the national bird of Panama, I went to an aviary where they were trying to breed the birds for a release programme. I can remember quite clearly seeing a large female eagle. I was struck by her huge legs and thick, long talons. I also recall the person I was with saying that it was “a scary, no-nonsense bird,” but sitting there on a perch barely moving and seemingly oblivious of the world around her she didn’t seem too threatening.
Then a toddler came around the corner, a lively child somewhere between two and three. The eagle visibly stiffened. Its entire demeanor changed in a heartbeat. It swiveled its head towards the child, leaned forward and, like a switch had been thrown, turned from almost asleep to hyperalert. I was with two other people and we all had the same goosebump feeling. The eagle had seen prey.
That harpy eagle may have perked up at the sight of a small child, but grown adults had no effect on it whatsoever. This is hardly surprising, because adults are well outside the realistic size range for prey of even the very largest eagle species.
There is only a handful of truly large eagles in the world: the harpy, the Philippines eagle, the African martial eagle, the African crowned eagle, Steller’s sea eagle and the white-tailed eagle. Each of these massive raptors is certainly impressive and it is clearly possible for a large eagle to swoop down and embed its massive talons in your skull. This would very probably be a fatal wound.
With its beak and talons an eagle could then eat portions of you while you were dead on the ground. From that point, it would be a trivial exercise for the eagle to take some morsels back to its chicks. In principle all this is possible, but there are just no credible reports of this happening to adults. Children are a different story.
Harpy eagles can pluck black howler monkeys directly from the tree canopy. Howlers are the largest monkeys in Latin America, with males reaching 60–65cm (2ft–2ft 2in) in length excluding a long tail and 12–14kg (26– 31lb) in weight. That is in the same ballpark as an 18-month-old or small two-year-old. A human toddler is certainly a possible prey item, but despite this there seems to be no credible report of a harpy eagle taking a child.
A factor in this might be the way harpy eagles hunt. A massive eagle adapted to dense tropical forest canopy hunting might find it difficult to take a child at ground level. On the other hand, eagles adapted for hunting ground-based prey in more open country, or in woodlands, might find a child easier to take. It is to these species we must look if we want to find out whether eagles predate children.
The crowned and martial eagles of Africa are good candidates. Both species are large, with the martial eagle being the larger. I’ve seen both species and, in the flesh, martial eagles are comfortably the more impressive of the two. Height- and weight-wise, though, neither African species is as large as the harpy eagle, although the martial eagle has a larger wingspan than its Latin American cousin.
Despite being smaller and less imposing than the martial eagle, it is the crowned eagle that is considered the more powerful in terms of the prey it is able to tackle. Crowned eagles have been known to hunt bushbuck (a small species of antelope) and in some parts of their range they frequently take large monkeys of a not dissimilar size to a toddler.
The big difference between these eagle species and the harpy eagle is that the African species tend to live in far less densely forested areas, and they will take prey at ground level far more often. Harpy eagles can and will take prey on the ground, but they tend not to. One study found that 79 per cent of all prey was sloths taken from trees, and tree-living monkeys make up most of the rest. The majority of harpy eagle prey thus weighs 2–3kg (4–7lb) and lives in the top branches of dense tropical forests. On the other hand, martial eagles and crowned eagles have diets that include ground-living mammals larger than a toddler including duikers (a 15kg/33lb antelope), Thomson’s gazelle and impala.
It is the more powerful crowned eagle, with its dietary penchant for primates, which seems the most likely species to target humans. There is some evidence to support the idea that this happens, albeit very rarely. The most definitive reported case is described in Peter Steyn’s Birds of Prey of Southern Africa: their identification and life histories.
For an eagle to attack a 20kg boy far from a nest strongly suggests predatory intent.
According to the author, a seven-year-old boy was attacked and “savagely clawed’”on the head, arms and chest by an immature crowned eagle, and was only saved by the quick actions of a woman brandishing a hoe. The eagle did not survive, but the boy, Damas Kambole, was successfully treated at a nearby mission hospital.
The incident occurred far from any known nest and the bird was immature, which are important facts for interpreting what occurred. Eagles, like many birds, can be highly defensive of their nests, especially if chicks are present, but for an eagle to attack a 20kg (44lb) boy far from a nest strongly suggests predatory intent. There is other evidence of crowned eagles taking children.
Raptor conservationist Simon Thomsett describes a “macabre anecdote” while “investigating an alleged kill of a human infant (four-year-old girl).” He was “brought to the tree where her severed limb was found. The circumstances led to no doubt that the accusation [that the child was taken by an eagle] was true, for no leopard could have climbed that tree.” A portion of a child’s skull has also been found in the nest of a pair of crowned eagles, although in that case scavenging could not be ruled out.
The larger but less powerful martial eagle has also proved capable of attacking and killing human children. In 2019 in the district of Gaashaamo in the Somali region of Ethiopia, a child was killed by a martial eagle that also wounded at least two more children. The eagle was subsequently killed, with some reports suggesting it was shot, but others reporting that a teenager killed it with a cane after the eagle had attacked him.
Whether these attacks were defensive or predatory in intent is impossible to determine, but they nonetheless clearly demonstrate two facts: eagles can and sometimes do attack people, and they can kill us.
There is some tantalizing evidence that eagle predation may have been a more important factor in our evolutionary past, when our ancestors were smaller. Also, as we’ll see shortly, some extinct species of eagles were considerably larger than modern-day species.
The Taung Child is a fossilized skull of an Australopithecus africanus, a species of hominin that lived in South Africa between 2 and 3.7 million years ago. The Taung Child, was found in 1924 by quarrymen working in a limestone quarry near the small town of Taung in North West province, South Africa. The town’s name means “place of the lion,” the Tswana word for lion being tau, but it is a different predator that has become inextricably linked with the Taung Child.
The history of the Taung Child fossil is a fascinating story in itself, with the Piltdown Man hoax casting a shadow over initial claims that the skull represented a human ancestor. Eventually, over the course of several decades, the skull was accepted as being that of Australopithecus africanus and is now considered one of the most important hominin fossils. Indeed, the Taung Child is still intensely studied close to a century after its discovery. One such study, published in 2006, concentrated on the possible cause of death. This is where an eagle enters the story.
Lee Berger is an American-born paleoanthropologist in South Africa, as well-known for his discoveries as for his high public profile. He is perhaps best known for leading the expedition that found another hominin, Homo naledi, in the Rising Star Cave system in South Africa, a discovery that was published in 2015.
Before that discovery, he become well known for advancing the Taung bird-of-prey hypothesis. In 2006, he published a short paper that compared the skull damage of monkeys that had been killed by crowned eagles with some distinctive damage discernible in the Taung Child’s skull.
Berger found that, “Re-examination of the Taung juvenile hominin specimen … reveals previously undescribed damage to the orbital floors [the base of the eye socket] that is nearly identical to that seen in the crania [skulls] of monkeys preyed upon by crowned hawk eagles [an alternative common name for the crowned eagle].”
Other non-hominin bones found with the Taung Child lend weight to the idea. The assemblage of bones is typical of the accumulation of prey species’ remains associated with birds of prey. Taken together, the evidence strongly points to the Taung Child having been taken by an eagle.
The Taung Child was small. Estimated at just over 1m (3ft 3in) tall and weighing around 10kg (22lb), they would have been the size of a small two-year-old modern human, or more realistically, perhaps a large 18-month-old toddler. Taller, but lighter, than a howler monkey from South America, and a little heavier than a typical vervet monkey from Africa, the Taung Child is certainly in the prey size spectrum of modern eagles, but arguably only just. Human size is of course only one side of the eagle-human equation. The other way to push humans into the prey spectrum of eagles is to make the birds larger.
No account of eagles hunting humans would be complete without mention of the largest eagle known to have existed, the mighty Haast’s eagle. Estimated to have weighed 15–18kg (33–40lb)—comfortably 50 percent heavier than the harpy eagle, and perhaps as much as 100 percent heavier than a typical individual—Haast’s eagle was native to the South Island of New Zealand and went extinct around 1400. Its large size has been explained as an evolutionary adaption to hunting moa, the huge flightless birds that used to roam New Zealand, now also sadly extinct. Looking like an oversized emu, the largest species of moa were more than 3m (9ft 11in) tall and weighed in excess of 200kg (441lb).
To explain Haast’s eagle’s large size we need to explain the moa’s large size—and to do that requires a small detour into some evolutionary theory.
The huge size of New Zealand moas is attributed to an evolutionary process termed “island gigantism,” whereby small species that end up on islands tend to increase in body size. One reason for this evolutionary increase in size is that large mammalian predators are often absent from islands. It is much harder for a big predator to make it to an island.
Being small, and able to escape and hide, is a good adaptation to counter predators, but if predators are absent then prey is released from this constraint. Colonizing islands is not easy, so those that manage it may not have much competition from other species. This lack of competition and absence of predation can favor larger, slower-growing individuals, a pressure that over time can lead to exaggerated size and, in birds, a loss of flight.
The dodo, essentially a giant pigeon, is a good example, as are the elephant birds of Madagascar. Similar to the moas, elephant birds were generally more heavy set; the largest species, Vorombe titan, was slightly shorter than the largest moa but close to three times its weight. The evolutionary flipside to island gigantism is “island dwarfism.” In this case, evolutionary pressures push animals in the opposite direction and favor small size. One explanation is that if food resources are limited then conditions favor animals that mature earlier at a smaller size. Individuals that are smaller and breed sooner produce more offspring over time than larger, later-breeding individuals and so smaller forms come to dominate.
A detailed study of bones, especially the pelvis, suggest that the bird was more than capable of delivering a fatal blow when swooping on prey.
One well-known extinct example of island dwarfism is an elephant that lived on Malta and Sicily. This species stood less than 1m (3ft 3in) high, and weighed less than 300kg (661lb). It is thought that the skulls of these tiny elephants may have led to the legends of Cyclops in Greek and Roman mythology. Elephant skulls are distinct in having a large central nasal cavity accommodating the trunk, which appears as a big hole in the middle of the front of the skull and could be mistaken for a single large eye socket.
But back to pre-1400 New Zealand and Haast’s eagle. CAT scans of what remains we have of these birds were used to study their evolution and to infer features of their lifestyle and ecology. The only extant species of birds that are meaningful comparators to the Haast’s eagle are vultures and condors. Both of the largest species, the black vulture (around 14kg/31lb) and the Andean condor (around 15kg/33lb), are a little smaller than the largest estimates we have for Haast’s eagle, but they are in the right ballpark.
Both of these birds are predominately scavengers and, because its beak was similar to the beaks of vultures, it has been suggested that Haast’s eagle had a similar scavenging lifestyle. However, a detailed study of bones, especially the pelvis, suggest that the bird was more than capable of delivering a fatal blow when swooping on prey. The study provided what palaeontologist Trevor Worthy described in an interview on ABC News as, “convincing data [showing] beyond doubt that this bird was an active predator, no mere scavenger.”
We already know that extant eagles can potentially kill small humans and, having established the credibility of Haast’s eagle as a predator, the size of the bird clearly represented a threat to humans. The first Māori arrived in New Zealand South Island around 1300 and it is their hunting of moa that likely precipitated the relatively rapid extinction of Haast’s eagle.
However, between early colonization of potential prey and the eventual extinction of predator there was plenty of time for interactions, some of which may have made their way into mythology. Māori stories include the pouakai (or poukai), a massive bird that killed and ate people, the origin of which may have been Haast’s eagle.
As one of the authors of the bone study, Paul Scofield, puts it, “The science supports Māori mythology of the legendary pouakai or hokioi, a huge bird that could swoop down on people in the mountains and was capable of killing a small child.”
Scofield suggests that the eagle also seems likely to be Te Hokioi, a massive black-and-white aerial predator with a red crest and yellow-green wingtips described to Sir George Grey, an early governor of New Zealand and later its 11th premier.
A British soldier, explorer and writer, Grey was no ordinary colonial. He learnt the Māori language and was able to persuade Māori authorities to write down their legends and history. While no longer with us, Haast’s eagle at least lives on through the stories passed down.
From The Deadly Balance. Used with the permission of the publisher, Bloomsbury Sigma. Copyright © 2023 by Adam Hart.