Pacific settlement caused mass bird extinction

The total extinction toll is likely to have been around 1,300 bird species. Photo / Supplied

The migration of humans across the Pacific Islands resulted in the mass extinction of more than 1,000 species of bird, researchers claim.

A study, carried out by the Zoological Society of London, looked at the influence overhunting and deforestation had on bird species as the first people arrived in the tropical Pacific Islands from about 4,000 years ago.

"We studied fossils from 41 tropical Pacific islands and using new techniques we were able to gauge how many extra species of bird disappeared without leaving any trace," said Professor Tim Blackburn, the director of ZSL's Institute of Zoology.

They found that 160 species of non-passerine land birds (non-perching birds which generally have feet designed for specific functions, such as webbed for swimming) went extinct without a trace after the first humans arrived on these islands alone.

"If we take into account all the other islands in the tropical Pacific, as well as seabirds and songbirds, the total extinction toll is likely to have been around 1,300 bird species," Professor Blackburn said.

The findings have been published today in the journal Proceedings of the National Academy of Sciences.

Human settlement often leads to extinction. When humans arrived on remote Pacific Islands, they found vulnerable flightless birds easy to hunt. Other species were driven to extinction due to decimation of their habitats.

"You can imagine, when you don't have chainsaws and things, the easiest way to clear forest is to set it on fire," lead author Richard Duncan of the University of Canberra told Science Now.

The researchers note that New Zealand got off lightly as it is a large, mountainous and wet island, suffered less deforestation, and had more places for birds to hide from hunters.

Species lost include several species of moa-nalos, large flightless waterfowl from Hawai'i, and the New Caledonian Sylviornis, a relative of the game birds but which weighed in at around 30kg, three times as heavy as a swan.

Small, dry islands lost more species because they were more easily deforested and had fewer places for birds to hide from hunters. Flightless birds were over 30 times more likely to become extinct that those that could fly.

Bird extinctions continued with the arrival of Europeans in the Pacific, with another 40 species disappearing and many more species threatened with extinction today.

- Herald Online