Harpagornis moorei

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Kingdom Animalia (animals)

Giant Haast's eagle attacking New Zealand moa. Created by John Megahan. Copyright PLoS Biology. This image has been released under the Creative Commons Attribution ShareAlike 2.5 Licence.

Phylum Chordata (chordates)
Class Aves (birds)
Order Falconiformes (diurnal birds of prey)
Family Accipitridae (eagles, hawks, and kites)
Genus Harpagornis
Species Harpagornis moorei
Authority Haast, 1872
 
English Name Haast's Eagle, New Zealand (Giant) Eagle
Dutch Name Haasts Arend, Reuzenarend
French Name Aigle géant
German Name Haastadler, Riesenadler
Maori Name Te Hokioi, Te Pouakai
 
Comments Dr. Julius von Haast described two species of eagle, one on the basis of small bones which are now believed to represent the male. Harpagornis assimilis Haast, 1874, is a synonym of Harpagornis moorei Haast, 1872. Given its similarity to the smaller Hieraaetus species, Michael Bunce et al. (2005) recommend reclassifying the New Zealand giant as Hieraaetus moorei (Haast, 1872).

The Maori seemed to have called the bird Te Pouakai or Te Hokioi. Murdoch Riley in his forthcoming book on Maori bird lore says that most authorities favour Te Hokioi. Other authorities say that the bird was a very large hawk that lived on the tops of mountains, another that it stayed always in the sky and was a descendant of the star Rehua. It was regarded as the ancestor of ceremonial kites, which generally took the form of birds. Elsdon Best records that it was a legendary bird, reputed to carry off and devour men, women and children. The birds were also depicted in rock drawings.

 
Characteristics Haast’s eagle was the largest eagle ever to have lived and is the only eagle in the world ever to have been top predator of its ecosystem. Haast’s eagle was a large eagle with a low, narrow skull and an elongated beak. The males were smaller than the females. It had relatively short wings for its size: these were designed for flapping flight not for soaring. Its wing structure also helped it to catch and subdue prey as large as, or larger than, the eagle itself, and was better suited for fast, manoeuvrable flight in dense forest. Because of its large size, Haast’s eagle was approaching the upper limit of size for flapping flight – if it got any bigger it would have had to rely on gliding. Its leg bones were better suited for perching or for gripping prey than for walking about on the ground. The structure of the foot and length of the talons meant that Haast’s eagle could apply much greater force with its feet than other birds of prey. The talons could stab several centimetres into flesh, and often punctured bones as well. Weight: approximately 10-13kg; Wingspan: up to 2.6m for a large female. According to a Maori myth the Haast's Eagle made the following cry: "Hokioi-hokioi".
 
Lifestyle The Haast’s eagle is unusual, because of the sheer size of many of its prey. Most eagles kill animals that are less than their own body weight. This is because they have to be able to fly while carrying their kill. As there were no terrestrial predators bigger than a tuatara (a reptile about 500g-1kg in weight) in New Zealand, the Haast’s eagle only had to defend its meal from other eagles, and thus didn’t have to carry it to a safe place to eat it. The eagle attacked a variety of flightless birds found in New Zealand including the now extinct moas. It would launch itself from a high perch onto its prey and strike at the moa’s side. Its large talons grasped the hindquarters of the moa, and killed it by inflicting deep crushing wounds that caused massive internal bleeding. The moa perished from shock or blood loss. Over a dozen fossil moa have been found with gashes and punctures from eagle claws on their pelvis. Fossil moa bones show us how the eagle used its beak after it had caught its prey: it used the elongated beak to open up the carcass and reach inside to grab mouthfuls of organs such as the kidneys.
 
Range & Habitat Fossils have been found all across South Island, New Zealand. Fossil evidence shows that the areas where the Haast’s eagle lived were covered in forest and shrub lands, as well as in the grasslands on river floodplains.  

Research by Dr. Richard Holdaway on the skeletal remains of the birds suggests that the New Zealand eagle was a forest eagle that could not soar but probably hunted like other forest eagles by perching high on a branch until a suitable prey came within range and then diving on it at speeds of up to 80 kilometres an hour. The impact, which could knock even the largest Moa off its feet, was cushioned by powerful legs. The brutal talons were then used to crush and pierce the neck and skull of the immobilised prey. The eagle and its mate could remain near the kill for several days. Like all eagles the Haast also ate carrion and preyed on trapped animals when these were available.

With a life span approaching 20 years, the eagles occupied, in pairs, territories up to several hundred square kilometres. They were found mainly in the drier eastern forest during the Holocene but were more widespread in the scattered forest and scrublands of the late Otiran Glaciations 20,000 - 14,000 years ago.
 
Food It preyed upon flightless birds, including various species of moa. Palaeontologists believe that its prey ranged in size from 1kg to over 200kg in weight - the latter being the giant moa (Dinornis giganteus). The most common prey was likely the flightless Finsch’s duck (Euryanas finschi), now extinct. As New Zealand lacked any terrestrial mammals, the Haast’s eagle was the top predator. When people arrived in New Zealand, the eagle may have mistaken them for moa and thus attacked and eaten them. For more information on how they attacked their prey, see Lifestyle (above).
 
Reproduction No fossils of eggs or chicks have been found. Images of Haast’s eagle are found in rock paintings drawn in the 13th and 14th century - not long after the Polynesians first discovered New Zealand.
 
History & Population DNA research showed that the Haast's eagle may have evolved from the little eagle Hieraaetus morphnoides (Gould, 1841) and the booted eagle Hieraaetus pennatus (Gmelin, 1788) as recently as 700,000 to 1.8 million years ago. Its increase in weight by 10 to 15 times in that period is the greatest and fastest evolutionary increase in weight of any known vertebrate. This was made possible by the presence of large prey and the absence of competition from other large predators. (Bunce et al., 2005)

The Haast’s eagle was found all over South Island during the Pleistocene, but was mostly restricted to the south and east of South Island after the end of the Ice Age. The arrival of people in New Zealand had unfortunate consequences for the eagle: by 1400 AD, most of the forest habitat it used had been cleared by fire, and most of the large flightless birds that it ate had been hunted to extinction. The Haast’s eagle was likely extinct by 1400 AD, although there are a few 19th century accounts of sightings of very large birds of prey in mountainous areas.

 
Extinction Causes The Haast eagle succumbed to the environmental damage resulting from Polynesian colonisation. It became extinct probably several hundred years ago, along with the Moa, its main food source. Trevor Worthy says that Maori did kill them as their bones have been found in middens and fashioned into tools.
 
Museum Specimens The first discovered bones of this species were found in 1871 during excavation of Moa bones at Glenmark swamp in Canterbury. They were described in 1872 by Dr Julius von Haast, first director of the Canterbury Museum, who named the bird after George Moore, owner of Glenmark Station on which so many sub fossil bird bones were found. Only three complete skeletons have been found: two found late last century are in the Otago Museum in New Zealand and the Natural History Museum in London: the third, found in a cave near Nelson in 1989, is held by the National Museum in Wellington.
 
Relatives Scientists studying the giant bird have always thought it was related to the Australian Wedge-tailed Eagle (Aquila audax). But DNA research by universities in New Zealand and at Oxford have put an end to that theory. The results found the Haast's Eagle was in fact related to the small eagle species in the genus Hieraaetus, namely the Little Eagle Hieraaetus morphnoides (Gould, 1841), and the Booted Eagle Hieraaetus pennatus (Gmelin, 1788). In fact, Harpagornis moorei is more closely related to the Little Eagle and Booted Eagle, than these are to other members of the genus Hieraaetus. Thus, Harpagornis moorei should probably be reclassified as Hieraaetus moorei (Haast, 1872), pending confirmation. (Bunce et al., 2005)
 
Links

BBC - Science & Nature - Wildfacts - Haast’s eagle, New Zealand Giant Eagle.

Harpogornis moorei.

Hokioi.

Haasts arend - Harpagornis moorei - De roofvogelsite van Robert Goedegebuur. (Dutch)

 
references Bunce et. al., 2005. Ancient DNA Tells Story of Giant Eagle Evolution. PLoS Biol 3(1): e20 <Full-text | Print PDF (3767K) | Screen PDF (1307K)>

Bunce M, Szulkin M, Lerner HRL, Barnes I, Shapiro B, et al. (2005) Ancient DNA Provides New Insights into the Evolutionary History of New Zealand's Extinct Giant Eagle. PLoS Biol 3(1): e9 <Full-text | Print PDF (3124K) | Screen PDF (178K)>

Last updated: 21st September 2005.

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