Haasts Eagle

Scientific name: Harpagornis moorei Scientific classification:

Phylum: Chordata Class: Aves Order: Falconiformes Family: Accipitridae

When did it become extinct? Haast's eagle is thought to have become extinct around 500 years ago, although it has been said that the species managed to survive into very recent times.

Where did it live? The eagle was found only in New Zealand.

Before the arrival of humans, birds ruled New Zealand. In the absence of mammalian predators, many of the feathered denizens of these islands gave up flying, and some of them evolved into giants such as the moa (see the entry earlier in this chapter). These islands were a treasure trove of animal prey for the animals that could reach them, and sometime between 700,000 and 1.8 million years ago, some small raptors, very similar to the extant little

Haast Eagle
Haast's Eagle—Haast's eagle was an enormous bird that was a specialist predator of New Zealand's extinct moa. (Renata Cunha)

eagle (Aquila morphnoides), were perhaps caught in a storm and blown off course, eventually finding themselves in the strange land of New Zealand, where their bird relatives quite literally ran the roost. This land was full of opportunity. Many of the native New Zealand birds were flightless herbivores and omnivores. There was a vacancy in New Zealand for an aerial predator that could tackle the numerous ground-dwelling birds, and the little lost eagle evolved rapidly to fill this niche. For much of the time, evolution moves at quite a slow pace, but if there's a space in an ecosystem, a species can evolve very rapidly to fill it. This is what happened with the ancestors of Haast's eagle, as a small bird of prey evolved into the largest eagle that has ever lived and the only eagle that has been the top predator in its ecosystem.

As with other top predators, Haast's eagle was probably never very common, and because of this, the remains of this fearsome predator are scarce. Three complete skeletons are known (the latest of which was discovered in 1990) as well as numerous fragmentary remains. The bones show just how big this eagle was. It has been estimated that a fully grown female weighed 10 to 15 kg and was 1.1 m tall, with a wingspan of around 2.6 m. This is approaching the limit of how heavy a bird dependent on flapping flight and maneuverability can be. For comparison, the heaviest living eagle, the harpy eagle (Harpia harpyja), weighs around 8 kg. The skull of Haast's eagle was around 15 cm long, but the bill was not as bulky as those of large, living eagles. Its claws are thought to have been tremendously powerful, and they were tipped with enormous, 7-cm-long talons.

For its size, Haast's eagle actually had short wings, a characteristic it shared with the harpy eagle. Many eagle species have long, broad wings, allowing them to soar effortlessly at high altitude for long periods of time, but in those species that have evolved in forest habitats, long wings would be a disadvantage. In these situations, stubbier wings are a much better bet, and because of this, it is thought that Haast's eagle was an animal of forests and bush.

With its great size, terrible talons, and maneuverability, Haast's eagle must have been a formidable predator, but what did it eat? At least a dozen moa skeletons have been found that bare gouges and scars in the bones of their pelvis. Until the arrival of humans, Haast's eagle was the top predator in New Zealand, and it is highly likely that the marks on these moa bones were caused during a predatory attack by Haast's eagle. From a perch in a tall tree, Haast's eagle surveyed its territory for moa and other large, ground-dwelling birds, and on sighting some suitable quarry, it launched an assault. Swooping toward the prey at a speed of between 80 and 100 km per hour, it swung its terrible talons forward in preparation for the contact. The eagle's powerful legs absorbed the force of the impact, but the prey was probably knocked clean off its feet. If the initial strike was not enough to kill the prey, the puncturing force of eight huge talons caused massive internal bleeding, and before long, the victim succumbed to blood loss and shock. With its prey dead, the eagle used its talons and beak to tear the skin of the hapless victim before digging into its flesh.

The large living eagles most often take prey that is considerably smaller than themselves so they can carry it away to a safe perch out of the way of scavengers. There were no scavengers in New Zealand large enough to challenge a Haast's eagle for its kill, and therefore it could tackle large prey and eat them where they died. At a kill, the only animals a Haast's eagle feared were others of its kind.

As formidable a predator as it was, the Haast's eagle was no match for humans, who first reached New Zealand around a.d. 1300. It is now a largely accepted theory that humans, through hunting and habitat destruction, brought about the extinction of the moa and many other unique New Zealand birds. Humans undoubtedly saw and knew this raptor, and whether they persecuted it or revered it is a bone of contention. In some cultures around the world, top predators are persecuted by humans, while in others, these animals are revered. Perhaps the Maori hunted Haast's eagle, not only because it competed with them for their food, but also as an act of reverence. In many aboriginal cultures, the body parts of powerful predators are collected and worn in the belief that the strengths of the animal will be transferred to the wearer. Hunting and dwindling prey probably killed off the Haast's eagle before the last moa disappeared.

♦ For a long time, it was assumed that Haast's eagle evolved from the wedge-tailed eagle that is found throughout Australasia. Recently, scientists managed to extract some DNA from Haast's eagle bones, and this was compared to the DNA of living eagles. This showed that the closest relative of Haast's eagle is the little eagle. Constructing a family tree from ancient DNA should always be done with caution as thousands of years lying in the ground can severely damage DNA, and old samples can be contaminated with DNA from sources too numerous to list.

♦ A famous New Zealand explorer, Charles Douglas, a man who was not prone to exaggeration and flights of fancy, claimed in his journal that he had an encounter with two giant birds of prey in the Landsborough River Valley of South Island sometime in the 1870s. If this is true, is it possible that Haast's eagle somehow clung to existence in a remote part of New Zealand until very recent times? Unfortunately, we'll never know the truth as Douglas killed and ate both of these mysterious birds.

♦ The bones of another giant raptor have also been found in New Zealand, and these are now thought to have once belonged to a massive type of harrier. Harriers are lightly built birds of prey weighing in at around 700 g. The New Zealand giant harrier (Circus eylesi) was more like 3 kg.

Further Reading: "Ancient DNA Tells Story of Giant Eagle Evolution." PLoS Biology 3 (2005): e20; Bunce, M., M. Szulkin, H.R.L. Lerner, I. Barnes, B. Shapiro, A. Cooper, and R. N. Holdaway. "Ancient DNA Provides New Insights into the Evolutionary History of New Zealand's Extinct Giant Eagle." PLoS Biology 3 (2005): e9; Brathwaite, D. H. "Notes on the Weight, Flying Ability, Habitat, and Prey of Haast's Eagle (Harpagornis moorei)'.' Notornis 39 (1992): 239-47.

Was this article helpful?

+2 0

Responses

  • essi
    How long is a haasts eagle?
    8 years ago
  • David Sankt
    Which eagle takes the most formidable prey,which eagle takes the most formidable prey?
    8 years ago
  • berto dellucci
    When was the first fossil of a haast eagle found?
    8 years ago
  • Boris
    What the conclusion too haast eagles?
    9 months ago
  • coby
    Did humans hunt haast eagles?
    6 months ago

Post a comment