The plight of wild gorillas has taken a turn for the worse, according to the latest edition of the World Conservation Union (IUCN) Red List of Threatened Species. Western gorillas (Gorilla gorilla), which live in the western Congo basin, have moved from 'endangered' to 'critically endangered' in the 2007 list. And conservationists anticipate that the mountain gorilla (G. beringei), which is now found only in Rwanda, Uganda and the eastern Democratic Republic of the Congo, will follow suit once its population survey is completed.

The number of western gorillas has declined by more than 60% in the past 25 years, according to the new assessment, published on 12 September. The Ebola outbreak that has hit the main subspecies, the western lowland gorilla (G. gorilla gorilla, pictured) is largely responsible — wiping out roughly one-third of individuals in protected areas.

The population of western gorillas has been hit hard by the Ebola virus and poaching. Credit: M. WATSON/WWW.ARDEA.COM

The upgraded conservation status is mainly the result of the Ebola outbreak and a resurgent trade in bushmeat, says Russ Mittermeier, chair of the IUCN Primate Specialist Group in Arlington, Virginia. “The decline has been really precipitous,” he says. “Gorillas are still being sold as a luxury food item.”

Mountain gorillas are less numerous than western gorillas, but have not yet been upgraded to critically endangered. This is mainly because the most vulnerable subspecies (G. beringei beringei) — numbering barely 700 gorillas in the Virunga mountain range on the border of Rwanda and the Democratic Republic of the Congo — has been kept stable by a popular and well-managed tourism programme. But civil strife in the Congo means that this security is under threat. Last week, the conservation group WWF reported that park rangers had been leaving their posts in fear of armed rebels, who have already killed several gorillas within the Congo's parks this year.

The Red List contains details of some 41,000 species, of which more than 16,000 are officially threatened with extinction. Additions to the 2007 list include three species of coral, the first corals ever to be included. The Baji, or Yangtze river dolphin (Lipotes vexillifer), which is subject to widespread media speculation over its status, is now listed as 'critically endangered (possibly extinct)'.