The numerous islands scattered throughout the Pacific Ocean comprise the last habitable region of Earth that humans colonized. Beginning about 3500 years ago, people settled the eastern islands, such as the Samoan islands, Fiji and the Marianas. By 700 years ago they made their way to the more remote locations of Hawai‛i and Rapa Nui (Easter Island). These islands once held hundreds of species of birds that disappeared when humans arrived. Now we have a clearer picture of what happened.
The Pacific islands experienced a massive die-off of bird species not long after human colonization, but just how many of the feathery creatures went extinct has remained a bit of a mystery to scientists. Now, a new analysis suggests that some 1000 nonpasserine landbird species (birds that don't perch) disappeared due to hunting and habitat loss between the time people first settled the Pacific islands and the arrival of Europeans.
These tropical landscapes were once dominated by numerous bird species, many of which became extinct in a relatively short time after humans arrived. Some conservative estimates say 800 species disappeared, while others place the number at over 2000. The main reason for this large extinction uncertainty is the spotty fossil record available, says Richard Duncan, an ecologist at the University of Canberra in Australia and lead author of the new study.
"Relatively few fossils have been collected from a lot of the islands that have been studied," Duncan told io9. Fossils will only preserve in certain types of sites -- these "specialized habitats" are often difficult to find. "And a lot of the work on collecting raw data and fossils [in the Pacific] has been done by just a few people," he adds. The large differences between the islands, including area, topographic diversity and rainfall, further complicates getting an accurate rate of species loss, since these features would've affected how easily people could hunt and clear out forests.
So Duncan and his colleagues used the available data to refine the Pacific islands' extinction estimates. The team focused only on nonpasserine landbirds, which are better represented in the fossil record than sea birds and passerine birds. The large-bodied landbirds preserve as fossils easier than smaller birds and were likely the prime target of hunters, who left the remains in more accessible sites.
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