Living bird species help estimate extinctions driven by humans

The first humans to colonize remote islands in the Pacific preceded a mass extinction of birds. Incomplete fossil records from these islands, however, have made it difficult to determine how many bird species went extinct during this first wave of human colonization.

An international research team has now overcome this obstacle by employing a mark-recapture method, reporting their findings in a recent issue of Proceedings of the National Academy of Sciences¹. Mark-recapture uses the number of extant bird species that have not been discovered on the fossil record to estimate the number of extinct species missing from the fossil record.

The researchers from the University of Canberra, University of Tennessee in Knoxville and King Saud University in Riyadh, used fossil bone data for large, flightless birds found across 41 Pacific islands, colonized by humans in the past 3,500 years. The rates of extinctions were much higher among the large flightless birds – easy prey for humans.

Besides hunting, humans also cleared forests, further accelerating the rate of extinctions. Human arrival, according to the researchers, drove at least 983 species of flightless birds to extinction from the remote Pacific islands.

"Smaller islands with lower rainfall had higher rates of habitat loss, contributing to higher rates of bird extinctions," says Richard P. Duncan, a co-author of the study.

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