Fast Facts Edit
- Type: Bird
- Diet: Carnivore
- Size: Males about 9-12 kg in weight, females about 10-15 kg in weight. Average wingspan of females about 2.6 meters wide, but some remains suggest a 3 meter wingspan is possible.
- Protection status: Extinct
- In the simplest terms, Harpagornis also known as the Haast's Eagle is in essence, a giant eagle, and one that focused upon hunting only the largest prey available to prehistoric New Zealand
- the large flightless moa birds. Isolated remains and estimates of them suggest that the largest Haast’s Eagles could attain a wingspan of up to three meters long, though a two and a half meter wingspan is more easily established from the majority of known remains. Even with the lower estimate however, Harpagornis still had a wingspan roughly equivalent to today’s largest eagles such as the Steller Sea Eagle (Haliaeetus pelagicus), Wedge-tailed Eagle (Aquila audax) and the Golden Eagle (Aquila chrysaetos). Where Harpagornis really wins in size though is by weight. Most modern eagles, including the females which are usually larger than the males, never exceed nine kilograms in weight when living in the wild (captive kept eagles are not included in case these are overfed). Estimates of male Haast's eagles however range from nine kilograms all the way up to twelve kilograms, while females could weigh as much as fourteen to even fifteen kilograms. This means that the Haast's eagle is probably one of if not the heaviest eagle that we know about to ever take to the air. Because of the extra weight, it is believed that a Harpagornis would launch itself into the air by jumping up from the ground while flapping.
Harpagornis was not a bird that was adapted for long range soaring over great open distances, the relative shortness of the wingspan is a clear indication that the Haast's Eagle was adapted for flight amongst trees and other locations where there was not much room to open up the wings. By proportion the tail has become enlarged to cover a larger surface area, something that would help to create lift in the absence of larger wings. A large tail would also allow for more stable and more manoeuvrable low speed flight, and would have enabled Harpagornis to have had an exceptional ability for tight turns while flying amongst trees. Harpagornis is also credited as having larger jaws than most modern eagles, as well as possessing several long talons on the feet. The talons of the Harpagornis are noted as being similar in form to those of the Harpy Eagle (Harpia harpyja). These talons were between forty-nine to sixty-one and a half millimetres long for the front toes while the talon of the hallux (the rear toe that was opposable to the others) was up to one hundred and ten millimetres long. It were these talons that would have been the primary killing weapons of an individual eagle. Harpagornis was adapted to hunt and kill large prey upon a one on one basis, but the only suitably large prey in New Zealand for such a large predator were the moa. Moa were large flightless birds which are known by several genera, the largest of which of the Dinornis genus (D. robustus and D. novaezelandiae) could grow up to around three and a half meters tall. These birds inhabited the forests that covered New Zealand during the Pleistocene and Holocene, and a possible hunting scenario plays out as so. A lone Harpagornis spots a moa moving though perhaps a less dense growth of trees and then moves itself into position for a strike. From an elevated position the Harpagornis begins a downward swoop toward the moa, picking up speed all the while it is making its approach. The moa may be too busy feeding or dinking to notice the approach of the eagle which may also be obscured slightly by the undergrowth. Before the moa can realise the danger the Harpagornis sinks its talons into the spine of the moa, which thanks to a combination of the sharp edges driven by the momentum of the heavy eagle travelling at high speed during the point of impact, easily slice and sever the spinal cord bringing instant paralysis. The easiest location for a Harpagornis to strike would be the pelvis or the backbone supporting the rib cage since these areas would not be as likely to move as the head and neck. A strike to the spine in these areas would also bring paralysis to the legs, causing the moa to collapse under its own weight. The eagle may have then used a series of strikes from its talons and beak to more quickly subdue the moa, or simply wait for the moa to weaken and die before feeding. The lack of large predators and scavengers on New Zealand meant that a single moa carcass could sustain an eagle for at least several days. The only real threat to a Haast's Eagle at this time would be if another came along and challenged it for territory. The precise classification of the Harpagornis seems to be up in the air at the time of writing. The Harpagornis genus has been well established for well over a century, and the popularity of this eagle has meant that most people know it as and continue to call it Harpagornis. However, a 2005 DNA study of Haast’s Eagle remains by Lerner and Mindell found that it was closely related to the Little Eagle and the Booted Eagle. Both of these eagles have now been re-classified under the Aquila genus, and now there has been quite a bit of speculation over whether Haast's Eagle should be added to the Aquila genus as a distinct species, or if it should remain in its own genus, Harpagornis. As it stands today, some people have already chosen to move Haast's Eagle over to Aquila, retaining the original species name to create A. moorei as opposed to H. moorei. Others however continue to creditHarpagornis as valid. At the time of writing no formal decision has been made to move Harpagornis to Aquila, but if this does happen then you can expect the genus naming confusion to continue for quite some time afterwards. This is what happened to a giant monitor lizard from Australia called Megalania. Modern analysis of the remains of this great monitor lizard have seen it become a species of the genus Varanus which includes modern monitor lizards, and although many scientific bodies now treat Megalania as Varanus priscus, the old designation of Megalania is still very common, especially within the realms of popular science and media. As both apex and specialised predators, the future of Haast's Eagles was certain for as long as there were moa to hunt. However, by 1250-1300AD New Zealand had been settled by the first Māori people, and this signalled the end for much of the native and specialised fauna of New Zealand. The first settlers needed to make the land suitable for long term habitation which meant that vast areas of forests began to be cleared, destroying the habitat of many animals. What had a larger impact upon the numbers of Haast's Eagles however was the active hunting of the moa birds by people. This caused a significant drop in the numbers of moa which meant that quite suddenly there was not enough food to support the population of Haast's Eagles which then began to decline. This continued all the time as the moa were hunted to extinction, and with the Haast's Eagles unable to switch to a different food source, they too followed the moa into extinction. Harpagornis is usually listed as going extinct at around 1400AD because this was about the time that the moa birds died out. It’s not inconceivable that Harpagornis might have survived for a little past this, especially if they had access to a small isolated population of moa that were still untouched. A claim was made by the explorer Charles Edward Douglas however that while he was travelling through the Landsborough River Valley in the 1870s, he shot and ate two raptors of exceptionally large size. Douglas noted that the birds had wingspans equivalent to around three meters and were probably the Pouakai of Maori legend. However there is some debate about whether Douglas correctly identified these birds. The Maori people at the time insisted that the Pouakai was a bird not seen in living memory, and so far known fossil specimens of Harpagornis confirm that these birds died out long before Douglas made his expedition. Instead, modern interpretation of Douglas’s tale is that he may have actually shot two Eyles' Harriers, a now extinct kind of harrier that was also noted for being unusually large, though not to the extent of the Haast’s Eagle. The reasoning for this is that although Eyles' Harriers succumbed to the same changing conditions as what finished Haast’s Eagles, their more generalist diet means that they may have managed to survive for longer that the more specialist Haast’s Eagles.