Some 40,000 years ago, a giant owl nested in a remote cave high in the Andes mountains. At a height of more than 2.3 feet and a wingspan of more than 5 feet, the Asio ecuadoriensis was an intimidating creature.
In the cave, scientists uncovered the remains of several small mammals like mice, shrews and rabbits, in addition to fossilized bird bones. The avian bones belonged to three other owl species—Tytp, Athene and Glaucidium—all of which exist today, reports Enrico de Lazaro of SciNews. Researchers say they show the kind of breakage and decay that is typical when bones are exposed to stomach acid.
The Asio ecudaoriensis bones are larger and do not show signs of having undergone digestion, suggesting it was likely the predator and owner of the burrow. In other words, this giant owl was cannibalistic.
"By finding the remains of the animals that had been the last meals of the Asio ecuadoriensis, we were able to know that, among mammals and birds, it consumed especially other types of owls, which shows us that this giant owl was practically what could be called a cannibal owl,” Frederico Agnolin, co-author of the study and researcher at LACEV-MACN, CONICET and the Fundación Azara says in a press release.
Erin Blakemore of the Washington Post reports that the modern great-horned owl and other species sometimes snack on owls. But the Asio ecuadoriensis is the first fossilized owl suspected of cannibalism.
“It is well known that owls usually prey on raptors, but predation on owls by owls is uncommon and remains poorly explored in the literature,” the authors wrote.
In a study published in the Journal of Ornithology, the team of South American researchers shared their findings from explorations between 2009 and 2012. They studied fossils in the Chimborazo province, at the geographic center of Ecuador. The fossils were discovered in volcanic sediment dating between 20,0000 and 42,000 years old, during the Pleistocene epoch. During this period, huge mammals like giant sloths, mastodons and saber-tooth tigers roamed South America.
While scientists have a sense of what kinds of mammals lived at that time, the history of the birds is more challenging to understand. Bird fossils are less easily preserved because their bones tend to be hollow and brittle.
Large birds of prey, in particular, are more acutely affected by dramatic climate changes because they have fewer offspring and adapt less easily than smaller birds. Researchers suspect that the Asio ecuadoriensis, like many large birds, suffered in the changing climate at the end of the Ice Age.
"We think that the climate change that occurred about 10,000 years ago, when the Ice Age ended, was partly responsible for the extinction of these large predatory birds of which they remain in currently very few species, such as the great eagles of the forests and the Andean condors," Agnolin says in the press release.