LONDON, March 26 (UPI) -- Thousands of bird species on isolated Pacific Islands, the last regions colonized by humans, went extinct soon after people reached there, scientists say.
The arrival of the first people in places such as Hawaii and Fiji 4,000 years ago caused irreversible damage to these natural havens due to over-hunting and deforestation, and led to the disappearance of many bird species, they said.
Scientists from the Zoological Society of London say fossil studies showed the scale and extent of these extinctions.
"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," zoologist Tim Blackburn said in a society release Tuesday.
They determined 160 species of non-passerine land birds -- non-perching birds that generally have feet designed for specific functions, such as webbed for swimming -- went extinct without a trace after the first humans arrived on these 41 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," Blackburn said.
Small, dry islands lost more species because they were more easily deforested and had fewer places for birds to hide from hunters, the researchers said, and flightless bird species were over 30 times more likely to become extinct that those that could fly.