This extinct eagle may have swallowed guts like a vulture

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At Craigmore Station in Canterbury, New Zealand, an ancient Maori painting graces the limestone overhang of a cave. The painted bird of prey, thought to represent an extinct eagle, gives the cave its name: Te Ana Pouakai, or the Eagle’s Cave. But this wasn’t just any bird — it may have been a Haast’s eagle, which had wingspans between six and three meters, making the species the largest eagle known.

The Maori artist painted the bird with a dark body and a head and neck circumference more reminiscent of a vulture’s bald head than an eagle’s feathered dome.

Now a group of scientists suggests that the extinct eagle may have looked just like its painted form. By creating 3D models of the extinct bird’s skull, beak and talons, the group tested how well the eagle performed against living birds of prey in a series of feeding simulations. Their results, published Wednesday in the journal Proceedings of the Royal Society B, claim that the Haast’s eagle hunted like a predatory eagle, but feasted like a scavenger vulture.

“It’s a unique, chimera-like combination for a bird,” said Stephen Wroe, a researcher at the University of New England in Armidale, Australia, and an author of the paper.

The Haast’s eagle became extinct around 1400 when its prey, the flightless moa, was hunted to extinction by Maori settlers. The eagles were gigantic, weighing up to 30 pounds. In Maori lore, Haast’s eagle may be represented by Pouakai, a giant bird of prey that can kill and eat humans.

Although the eagles were first described in the late 1800s, the question of whether the creature was a hunter or carrion feeder remained unresolved for decades. Recent analyzes of the eagle’s nervous system and its sensitive, powerful talons have strongly shown that the large bird killed prey like modern eagles.

“Modern eagles eat things smaller than themselves, so they can eat it in two or three bites,” said Anneke van Heteren, a researcher at the Bavarian State Collection for Zoology in Munich and an author of the paper.

But many scientists have pointed to the Haast’s more vulture-like features, such as bony structures around the nostrils, which help scavengers to feed on a much larger animal without accidentally suffocating themselves.

“If they stick their head in the gunk, they don’t want to get it up their nose,” said Dr. from Heteren. dr. Wroe had received CT scans of the skull of a Haast eagle about ten years ago. But the study of the animals that had potentially vulture-like features remained on the back burner for years until Dr. van Heteren took it upon himself.

The researchers used a technique called geometric morphometry, identifying landmarks on the bone, to record the shape of the Haast’s skull, beak and talons in three dimensions.

Just as eagles can specialize in hunting specific prey, vultures don’t all search in the same way. Some, known as ‘rippers’, feed on the tough skin of a carcass. “Gulpers” slurp up the soft, nutrient-rich entrails. And “scrappers” eat small scraps.

The authors compared their model of the Haast eagle with models of live vultures and eagles, which exhibited a range of feeding styles from hunting to scavengers. They examined the Egyptian vulture, a ‘ripper’ and the Andean condor, a ‘gulper’, as well as several eagles hunting prey of different sizes. The researchers ran the models through simulations of feeding behaviour.

“Vultures feed on animals much larger than themselves,” said Dr. Wrue. “They have to stick their heads deep into the abdominal cavity of a decaying zebra carcass and extract the high nutritional, soft internal organs: heart, lungs, liver.”

The Haast’s eagle model performed like a vulture in certain tests and like an eagle in others. It had the talons of an eagle and was excellent at biting prey. But it wasn’t very good at tearing off chunks of meat. It fed like a vulture, closely matching the gulping Andean condor in its ability to nose into a carcass.

The researchers say these results suggest that Haast’s eagle killed moa and then ate their guts. “It’s no small feat because it was an amazing bird,” said Dr. Wore about moas, which could weigh as much as 550 pounds.

Guillermo Navalón, a postdoctoral researcher at the University of Cambridge who was not involved in the study, said he felt the authors presented strong evidence for the Haast’s eagle’s hunting ability.

But he said the skull-shape similarity between the Haast eagles and vultures could be a result of their equal size rather than an indication of feeding behavior, pointing to a 2016 study that found that larger birds of prey have different skull shapes than smaller ones. birds of prey. dr. Navalón suggested that a more extensive analysis of the skull shapes could have clarified whether the similarities were related to scavenger, rather than just the large size of the birds.

As the paper nearly finished, one of the authors wondered if the Haast eagle was bald like many modern vultures. dr. van Heteren thought about the scientific rigor of European cave art, and the researchers scoured the internet for drawings of the Haast eagle in New Zealand caves.

During their search, they came across a photograph of the painted overhang of the Cave of the Eagle, showing the dark-colored bird with the uncolored head—perhaps evidence of baldness.

“If you look at it, I don’t know what else it could be,” said Dr. from Heteren. “These people were eyewitnesses, why don’t you take them at their word?”

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