At Craigmore Station in Canterbury, New Zealand, an historic Maori portray decorates the limestone overhang of a cave. Thought to depict an extinct eagle, the painted raptor provides the cave its identify: Te Ana Pouakai, or the Cave of the Eagle. However this wasn’t simply any hen — it might have been a Haast’s eagle, which had wingspans between six and 10 ft, making the species the most important identified eagle.
The Maori artist painted the hen with a darkish physique and an overview of a head and neck that’s extra harking back to the bald head of a vulture than the feathery dome of an eagle.
Now, a gaggle of scientists recommend the extinct eagle could have seemed similar to its painted type. By creating 3-D fashions of the extinct hen’s cranium, beak and talons, the group examined how effectively the eagle carried out towards dwelling raptors in a sequence of feeding simulations. Their outcomes, printed 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 singular, chimera-like mixture for a hen,” mentioned Stephen Wroe, a researcher from the College 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 had been gigantic, weighing as much as 30 kilos. In Maori lore, Haast’s eagle could have been represented by Pouakai, an enormous hen of prey that would kill and eat people.
Although the eagles had been first described within the late nineteenth century, the query of whether or not the creature was a hunter or carrion feeder went unresolved for many years. Latest analyses of the eagle’s nervous system and delicate, highly effective talons have made a powerful case that the big hen killed prey like fashionable eagles.
“Trendy eagles eat issues which might be smaller than themselves, to allow them to eat it in two or three bites,” mentioned Anneke van Heteren, a researcher on the Bavarian State Assortment of Zoology in Munich and an writer on the paper.
However many scientists have pointed to the Haast’s eagle’s extra vulture-like traits, equivalent to bony constructions across the nostrils, which assist scavengers feed inside a a lot bigger animal with out by chance suffocating themselves.
“After they get their head into the goo, they don’t need to get that of their nostril,” Dr. van Heteren mentioned. Dr. Wroe had acquired CT scans of a Haast’s eagle cranium round a decade in the past. However research 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 method known 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.
Simply as eagles can concentrate on looking particular prey, vultures don’t all scavenge in the identical manner. Some, referred to as “rippers,” feed on the robust 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 dwelling vultures and eagles, which exhibited a spread 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 way of simulations of feeding habits.
“Vultures feed on animals which might be quite a bit greater than themselves,” Dr. Wroe mentioned. “They must thrust their head deep into the belly cavity of a rotting zebra carcass and pull out the excessive nutrient worth, smooth inside organs: coronary 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 glorious at biting down on prey. Nevertheless it was not pretty much as good at ripping off chunks of meat. It fed like a vulture, carefully matching the gulping Andean condor in its capability to nostril inside a carcass.
The researchers say these outcomes recommend the Haast’s eagle killed moa after which ate their guts. “It’s no imply feat, as a result of it was a heck of a giant hen,” Dr. Wroe mentioned of moas, which may weigh as much as 550 kilos.
Guillermo Navalón, a postdoctoral researcher on the College of Cambridge who was not concerned with the research, mentioned he discovered the authors offered sturdy proof for Haast’s eagle’s looking prowess.
However he mentioned that the similarity in cranium form between the Haast’s eagle and vultures may very well be a results of their equally massive sizes somewhat than a sign of feeding habits, and pointed to a 2016 study that discovered bigger raptors have totally different cranial shapes than smaller raptors. Dr. Navalón recommended a extra complete evaluation of the cranium shapes may have clarified whether or not the similarities had been associated to scavenging, as a substitute of simply the birds’ massive measurement.
When the paper was almost completed, one of many authors puzzled if the Haast’s eagle was bald like many fashionable 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.
Of 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.
“If you take a look at it, I don’t know what else it may very well be,” Dr. van Heteren mentioned. “These individuals had been eyewitnesses, why not take their phrase for it?”
