Going or gone: defining ‘Possibly Extinct’ species to give a truer picture of recent extinctions

The IUCN Red List is widely regarded as the most authoritative classification of species by their extinction risk, including those species known to have become extinct in recent times. Birds are the best-documented class of organisms on the Red List, and the fourth complete assessment of the status of the world’s birds was recently published (BirdLife International 2004, IUCN 2004), and updated (at www.birdlife.org) for the 2005 IUCN Red List.