Mega-Swans May Have Once Roamed New Zealand

The Australian black swan may have once had a giant relative in New Zealand. picattos/Shutterstock

Josh Davis 26 Jul 2017, 15:26

The first people to land on the shores of New Zealand, which had been isolated from the rest of the world for tens of millions of years, would have stumbled upon another world. Rather than mammals being on top, they would have found birds dominating, including the massive moa and giant eagles. It now seems that they would have come face to face with mega-swans, too.

New research may have finally settled the debate about whether or not the southern nation was once inhabited by huge swans. Moriori legends tell of a monster swan-like creature, called the Poūwa (Cygnus sumnerensis), that used to waddle through the forests. Many assumed that these stories are simply exaggerations of the Australian black swan (Cygnus atratus), which are known to cross the Tasman Sea.

A study published in Proceedings of the Royal Society B has now conducted a genetic analysis on both the modern Australian black swans and the ancient swan fossils from the Chatham Islands off the New Zealand coast. The team found that the ancient bird was actually distinct enough to be considered a separate species, and that perhaps the legends of the native Moriori were indeed accurate after all.

The fossil bones of the newly described Poūwa suggest it split from its Australian cousin around 2 million years ago and went on a route of not only gigantism, but also its first steps towards flightlessness. The reconstructed skeletons of the now-extinct birds suggest it was around 20 percent heavier than the modern living species.

“One of the interesting findings comes from the highly elongated leg bones, which shows they were already on the path towards flightlessness,” says Dr Nic Rawlence, who led the research, in a statement. “Birds seem to get these elongated legs in island ecosystems where there are no mammalian predators and the top predators are birds, like the extinct Haast’s Eagle and Eyles’ Harrier.”

When Europeans first arrived in New Zealand, all they found were the remains of swans in the rubbish piles of Māori settlements. They presumed that these were the Australian variety and reintroduced the birds back in the late 1800s. It is now much more likely that these remains once belonged to the Poūwa.

It is now thought that humans most likely drove the mega-swans extinct, as they did the moa, which means the recent reintroduction of the Australian variety are technically an invasive species.

So if you find modern swans slightly terrifying, just be thankful you weren’t some of the first Māori coming face to face with their giant brethren.

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