Extinct bird of prey: once the king of bird paradise

New Zealand is home to a unique bird fauna.

Before Polynesians found a new home there, no mammals roamed the inland apart from a few bats.

Birds had therefore occupied many ecological niches in which mammals frolic elsewhere: for example, tiny passerine birds scurried across the forest floor instead of mice, and instead of hoofed animals, massive moas had attacked the plant world.

More bird species than anywhere else on earth had lost the ability to fly on New Zealand.

Because they didn't have to share their habitat with predators, they didn't need powerful wings to escape quickly.

When the ancestors of the Maori settled on the remote archipelago in the thirteenth century, it wasn't just the days of the Moas that were numbered.

The Haast's eagle - the only native animal that could harm these imposing ratites - went extinct just as quickly.

Hunt for oversized prey

Therefore, what scientists have discovered about the Haast's eagle is based primarily on the complete skeletons and scattered bones that have been unearthed during excavations.

With an estimated body weight of up to 15 kilograms, this bird of prey, scientifically called

, was significantly larger than any other eagle.

) , which is distributed from North Africa via Spain and Greece to Mongolia, and the Burrowing eagle (

) , native to Australia, turned out to be the

closest relatives.

At best, both birds of prey grow to the size of a common buzzard.

The molecular genetic family tree created by biologists around Michael Bunce from the University of Oxford suggests an unusually rapid evolution in body size: Apparently, in less than two million years, the ancestors of the Haast's eagle became as portly as possible without losing their ability to fly, as the researchers write in Plos Biology.

Although this New Zealand eagle remained smaller than the smallest moa species.

But even the largest representatives of these herbivores were not safe from him.

This is shown by relevant traces on the pelvic bones of a moa, whose weight is estimated at up to four hundredweight.

Apparently, the Haast's eagle could penetrate about two inches of skin and muscle tissue with its claws,

In order to find out how well the Haast’s eagle had adapted to oversized prey, scientists led by Anneke H. van Heteren from the Zoological State Collection in Munich took a closer look at the claws and the skull together with the beak.

Together with colleagues from Australia, the United States, Great Britain and New Zealand, they investigated the forces these skeletal parts could withstand.

They chose the finite element method, a numerical method that is suitable for modeling objects with complex shapes.

For comparison, three smaller eagle species and two vulture species were also included in the study.

XXL claws

As reported by van Heteren and colleagues in the "Proceedings of the Royal Society B", the Haast's eagle had typical eagle claws that could withstand enormous loads.

In terms of shape, they most closely resembled the claws of the closely related Burrowing Eagle, which originally only ate small birds, mammals, reptiles and insects.

However, as imported rabbits began to proliferate in Australia, this dainty eagle developed a fondness for these new prey animals, which often weighed more than itself. Similarly shaped, XXL-sized claws may have allowed the Haast's eagle to put moas of any size in its deadly grip to get.

The beak is also typical of an eagle, so it is good for powerful biting.

Otherwise, the skull of the Haast's eagle resembles that of the Andean condor, which would rather devour the entrails of a carcass than bother with tough skin and tendons.

Apparently

eagle-like with its clawed fangs for live prey, but then fed more in the style of a condor.

Because a bird's skin isn't typically as tear-resistant as a mammal's, the Haast's eagle probably didn't have a hard time gaining access to the muscles and internal organs.

Did he then specifically pick out special delicacies?

A bare head, as is usual with vultures, would then have proved useful.

An old rock carving on New Zealand's South Island suggests that Haast's eagles were actually equipped in this way: it shows a bird of prey whose body is dark in color - but the head is not.