Abstract

Conservationists predict massive extinctions as a result of habitat loss. Habitat loss undoubtedly does drive extinctions, but dealing with an unmet assumption that underlies these predictions yields much lower estimates. See Letter p.368 There is broad agreement that Earth is facing a biodiversity crisis, but estimating extinction rates remains a daunting task, not least because it is almost impossible to determine when the very last individual of a species has died. Fangliang He and Stephen Hubbell demonstrate that a widely used indirect method of estimating extinction rates — based on backward extrapolation of species–area relationship data — tends to overestimate the problem. As an example, they cite data on passerine bird species in the United States. He and Hubbell stress that habitat loss remains a real and growing threat to biodiversity, although we need to develop more reliable means of monitoring the situation.