Вадим Дудченко
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The Haast’s eagle (Hieraaetus moorei), the largest known eagle, habitually killed prey larger than itself, then applied feeding methods typical of vultures to feed on the large carcasses, according to new research.

An artist’s impression of the Haast’s eagle (Hieraaetus moorei). Image credit: Katrina Kenny.

The Haast’s eagle is a species of eagle that lived on the South Island of New Zealand until it went extinct until 600 years ago.

First described by Julius von Haast in 1871, the bird weighed up to 15 kg, approximately 30-40% heavier than the largest living eagle — the harpy eagle (Harpia harpyja).

The closest living relative of the Haast’s eagle is one of the world’s smallest eagles — the little eagle (Hieraaetus morphnoides).

The species was more than an order of magnitude heavier than the little eagle and represents an extraordinary example of rapid evolution within less than two million years.

“Most eagles hunt prey that is smaller than them, but the Haast’s eagle was going after moa that could weigh up to 200 kg — more than 13 times their own body weight,” said Dr. Paul Scofield, senior curator of natural history at Canterbury Museum.

“Condors also often eat animals that are much larger than them, so it makes sense that they’d have similar feeding habits.”

“As a result of this research, when we picture a Haast’s eagle feeding we can imagine them swooping down on a moa, grabbing on with those huge talons and using its powerful beak to deliver the killing blow. Once the moa was down, the eagle would go straight for the back of the skull and for the guts and other soft organs.”

In the study, Dr. Scofield and colleagues compared the skull, beak and talons of the Haast’s eagle with those of five living scavenging and predatory birds.

They found that the beak and talons of the Haast’s eagle were eagle-like.

However, the shape of its neurocranium — the section of skull that encloses the brain, and a key indicator of feeding behavior in birds — was most like that of the Andean condor (Vultur gryphus).

The condor is a gulper, a bird that feeds on the soft internal organs of a carcass. Its similarities to the Haast’s eagle suggest the latter probably also feasted on the guts and other internal organs of its prey.

If the Haast’s eagle ate like a condor, its head and neck might also have been featherless like that of the condor and most other vultures.

“This theory is supported by a Māori drawing thought to depict a Pouākai or the Haast’s eagle in the Cave of the Eagle at Craigmore Station in South Canterbury,” the authors said.

“In the drawing, the eagle’s body is colored black but its head and neck are uncolored.”

A paper describing the findings were published in the journal Proceedings of the Royal Society B.

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A.H. van Heteren et al. 2021. New Zealand’s extinct giant raptor (Hieraaetus moorei) killed like an eagle, ate like a condor. Proc. R. Soc. B 288 (1964): 20211913; doi: 10.1098/rspb.2021.1913

 



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