Birds die off faster due to human activities.

• Position: Extinction

Human activities have caused some 500 bird species worldwide to go extinct over the past 500 years, and 21st-century extinction rates likely will accelerate to approximately 10 additional species per year unless societies take action to reverse the trend, according to a report from Duke University, Durham, N.C.

Without the influence of humans, the expected extinction rate for birds would be roughly one species per century, maintains Stuart Pimm, professor of conservation ecology. 'What our study does is provide a well-justified and careful estimate of how much faster bird species are going extinct now than they did before humans began altering their environments."

"Habitat destruction, selective hunting, invasive alien species, and global warming are all affecting natural populations of plants and animals adversely," adds Peter Raven, president of the Missouri Botanical Garden, who is co-principal author of the report.

The researchers calculated that, since 1500--the beginning of the major period when Europeans began exploring and colonizing large areas of the globe--birds have been going extinct at a rate of about one species

per year, or 100 times faster than the natural rate--and...