The most common type of gorilla is now "critically endangered," one step away from global extinction, according to the 2007 Red List of Threatened Species released Wednesday by the World Conservation Union.
The Ebola virus is depleting Western Gorilla populations to a point where it might become impossible for them to recover.
Commercial hunting, civil unrest and habitat loss due to logging and forest clearance for palm oil plantations are compounding the problem, said the Swiss-based group known by its acronym IUCN.
"Great apes are our closest living relatives and very special creatures," Russ Mittermeier, head of IUCN's Primate Specialist Group, told The Associated Press.
"We could fit all the remaining great apes in the world into two or three large football stadiums. There just aren't very many left."
In all, 16,306 species are threatened with extinction, 188 more than last year, IUCN said. One in four mammals are in jeopardy, as are one in eight birds, a third of all amphibians and 70 percent of the plants that have been studied.
"Life on Earth is disappearing fast and will continue to do so unless urgent action is taken," the IUCN warned.
The Western Gorilla's main subspecies — the Western Lowland Gorilla — has been decimated by the Ebola virus, which has wiped out about a third of the gorillas found in protected areas over the last 15 years.
"In the last 10 years, Ebola is the single largest killer of apes. Poaching is a close second," said Peter Walsh, a member if IUCN's Primate Specialist Group, told the AP.
"Ebola is knocking down populations to a level where they won't bounce back. The rate of decline is dizzying. If it continues, we'll lose them in 10-12 years."
Decades to bounce back
Female gorillas only start reproducing at the age of 9 or 10 and only have one baby about every five years. Walsh said even in ideal conditions, it would take the gorillas decades to bounce back.
The World Conservation Union also said the Yangtze River dolphin is now "possibly extinct." There have been no documented sightings of the long-snouted cetacean since 2002. An intensive search of its habitat in November and December proved fruitless but more searches are needed as one was possibly spotted in late August.
The Redheaded Vulture soared from "near threatened" to "critically endangered." The birds' rapid decline over the last eight years is largely due to diclofenac, a painkiller given to ill or injured farm cattle so they can still work. But the substance poisons the vultures when they scavenge livestock carcasses.
Only 182 breeding adults of the Gharial crocodile remain, down almost 60 percent from a decade ago. India and Nepal's crocodile has become critically endangered because dams, irrigation projects and artificial embankments have reduced its habitat to just 2 percent of its former range.
The woolly-stalked begonia is the only species declared extinct this year. Extensive searches have failed to uncover any specimens of the Malaysian herb in the last century, IUCN said.
Only one species moved to a lesser category of threat. One of the world's rarest parrots 15 years ago, the Mauritius Echo parakeet, eased back from critically endangered to only endangered. That was a result of close monitoring of its nesting sites, and supplementary feeding combined with a captive breeding and release program.
IUCN says 785 species have disappeared over the last 500 years. A further 65 are found only in artificial settings such as zoos.
The Red List, produced by a worldwide network of thousands of experts, includes some 41,000 species and subspecies around the globe.