New Zealand was once home to some humongous birds, from the towering emu-like Moa, to the largest eagle ever known to exist, the Haast's eagle. Now researchers have confirmed the existence of yet another enormous avian, a semi-flightless mega-swan that went extinct less than two centuries after Polynesians first colonized New Zealand in the year 1280, reports New Scientist.
The find authenticates legends told by the Māori people, which speak of a mysterious bird called the Poūwa, a large swan-like creature. Though some physical evidence exists of New Zealand swans, paleontologists have long assumed that this merely pointed toward Australian black swans (Cygnus atratus) which are known to occasionally fly across the Tasman Sea.
Researchers were able to show that the Poūwa was distinct from the Australian black swan by comparing DNA from 47 modern Australian black swans and 39 ancient swan fossils uncovered from archaeological sites around New Zealand. The analysis suggested that the mega-swan would have split from the Australian black swan about 1 to 2 million years ago.
“We think Australian black swans flew to New Zealand at this time and then evolved into a separate species — the Poūwa,” explained Nicolas Rawlence at the University of Otago, one of the researchers involved with the study.
Although the Australian black swans and the Poūwa would have shared a common origin, the two species were quite dissimilar in appearance. Using fossil remains to reconstruct what the Poūwa looked like, the research team found that these mega-swans were 20 to 30 percent heavier than modern Australian black swans, and would have weighed more than 20 pounds. They also had short, stubby wings and long legs, suggesting that they would have had difficulty flying. Short flights would have been possible, but they would have been largely flightless.
Unfortunately, being poor flyers would have left them vulnerable to human hunters, and that's likely how these magnificent swans went extinct. Ancient trash heaps contain Poūwa remains, suggesting that the birds were commonly hunted for food. It's also likely that their eggs were eaten by rats that were introduced by the Polynesian settlers. Slow breeding rates are also common among large animals like the mega-swan, so that could have contributed to their speedy demise as well.
“Prior to Polynesian settlement, birds in New Zealand had a pretty easy life,” said Charlotte Oskam at Murdoch University in Perth, Australia. “They were naive to terrestrial predators and would have been easy pickings for the Polynesian settlers.”
The study was published in the Proceedings of the Royal Society B.