At Craigmore Station in Canterbury, New Zealand, an historical Maori portray decorates the limestone overhang of a cave. Thought to depict an extinct eagle, the painted raptor offers the cave its title: Te Ana Pouakai, or the Cave of the Eagle. But this wasn’t simply any hen — it might have been a Haast’s eagle, which had wingspans between six and 10 toes, making the species the biggest identified eagle.
The Maori artist painted the hen with a darkish physique and a top level view of a head and neck that’s extra paying homage to the bald head of a vulture than the feathery dome of an eagle.
Now, a group of scientists counsel the extinct eagle might have regarded similar to its painted kind. By creating 3-D fashions of the extinct hen’s cranium, beak and talons, the group examined how properly the eagle carried out in opposition to residing raptors in a sequence of feeding simulations. Their outcomes, revealed Wednesday within the journal Proceedings of the Royal Society B, argue the Haast’s eagle hunted like a predatory eagle however feasted like a scavenging vulture.
“It’s a unique, chimera-like combination for a bird,” mentioned Stephen Wroe, a researcher from the University of New England in Armidale, Australia, and an writer on the paper.
The Haast’s eagle went extinct round 1400 when its prey, the flightless moa, was hunted into extinction by Maori settlers. The eagles have been gigantic, weighing as much as 30 kilos. In Maori lore, Haast’s eagle might have been represented by Pouakai, a big hen of prey that would kill and eat people.
Though the eagles have been first described within the late 19th century, the query of whether or not the creature was a hunter or carrion feeder went unresolved for many years. Recent analyses of the eagle’s nervous system and delicate, highly effective talons have made a robust case that the massive hen killed prey like trendy eagles.
“Modern eagles eat things that are smaller than themselves, so they can eat it in two or three bites,” mentioned Anneke van Heteren, a researcher on the Bavarian State Collection of Zoology in Munich and an writer on the paper.
But many scientists have pointed to the Haast’s eagle’s extra vulture-like traits, similar to bony constructions across the nostrils, which assist scavengers feed inside a a lot bigger animal with out unintentionally suffocating themselves.
“When they get their head into the goo, they don’t want to get that in their nose,” Dr. van Heteren mentioned. Dr. Wroe had acquired CT scans of a Haast’s eagle cranium round a decade in the past. But examine of the animal’s doubtlessly vulture-like options remained on the again burner for years till Dr. van Heteren took it on.
The researchers used a approach referred to as geometric morphometrics, figuring out landmarks on the bone, to seize the form of the Haast’s eagle’s cranium, beak and talons in three dimensions.
Just as eagles can focus on looking particular prey, vultures don’t all scavenge in the identical approach. Some, often known as “rippers,” feed on the powerful pores and skin of a carcass. “Gulpers” slurp up the smooth, nutrient-rich innards. And “scrappers” eat small scraps.
The authors in contrast their mannequin of the Haast’s eagle to fashions of residing vultures and eagles, which exhibited a vary of feeding types from looking to scavenging. They examined the cinereous vulture, a “ripper,” and the Andean condor, a “gulper,” in addition to a number of eagles that hunted prey of assorted sizes. The researchers ran the fashions by simulations of feeding habits.
“Vultures feed on animals that are a lot bigger than themselves,” Dr. Wroe mentioned. “They have to thrust their head deep into the abdominal cavity of a rotting zebra carcass and pull out the high nutrient value, soft internal organs: heart, lungs, liver.”
The Haast’s eagle mannequin carried out like a vulture in sure assessments and like an eagle in others. It had the talons of an eagle and was wonderful at biting down on prey. But it was not nearly as good at ripping off chunks of meat. It fed like a vulture, intently matching the gulping Andean condor in its capability to nostril inside a carcass.
The researchers say these outcomes counsel the Haast’s eagle killed moa after which ate their guts. “It’s no mean feat, because it was a heck of a big bird,” Dr. Wroe mentioned of moa, which might weigh as much as 550 kilos.
Guillermo Navalón, a postdoctoral researcher on the University of Cambridge who was not concerned with the examine, mentioned he discovered the authors offered robust proof for Haast’s eagle’s looking prowess.
But he mentioned that the similarity in cranium form between the Haast’s eagle and vultures could possibly be a results of their equally giant sizes fairly than a sign of feeding habits, and pointed to a 2016 study that discovered bigger raptors have completely different cranial shapes than smaller raptors. Dr. Navalón urged a extra complete evaluation of the cranium shapes might have clarified whether or not the similarities have been associated to scavenging, as a substitute of simply the birds’ giant dimension.
When the paper was almost completed, one of many authors questioned if the Haast’s eagle was bald like many trendy vultures. Dr. van Heteren considered the scientific accuracy of European cave artwork, and the researchers scoured the web for drawings of Haast’s eagle in New Zealand caves.
In their looking, they stumbled upon a photograph of the painted overhang of the Cave of the Eagle, depicting the dark-colored hen with the uncolored head — proof, maybe, of baldness.
“When you look at it, I don’t know what else it could be,” Dr. van Heteren mentioned. “These people were eyewitnesses, why not take their word for it?”
