Several species of apes, monkeys and other primates could soon become extinct, warns a comprehensive new report released Thursday.
The study was compiled by 50 experts in 16 countries who found deforestation, commercial bushmeat hunting and illegal animal trading are the primary threats. It concludes that 25 percent of the 625 known primate species are at risk of extinction.
The report, "Primates in Peril," was a joint project of the World Conservation Union, the International Primatological Society and Conservation International.
"More and more, mankind's closest living relatives are being cornered into shrinking areas of tropical forest," said Russell Mittermeier, president of Conservation International.
A list of 25 most endangered primates accompanies the report. Of the 25, seven have been added since a similar report in 2002. All are in "biodiversity hotspots," 34 regions that cover just 2.3 percent of the Earth's land area but harbor more than half of all terrestrial plant and animal diversity.
A separate study last fall concluded Earth's biodiversity "is declining at an unprecedented rate." That report labeled 15,589 plants and animals as threatened for extinction. In December, the World Wildlife Fund said Bonobos, or pygmy chimpanzees, have been hunted so extensively that their survival is at risk.
"Southeast Asia's primates are subject to relentless poaching because of the profits to be made from the illegal trade," Chantal Elkin, manager of the Threatened Species Program at Conservation International, said in a statement Thursday.
"Although some of the region's threatened primates are taken as pets -- notably orangutans and gibbons -- they are most often hunted and traded for use in traditional medicines," Elkin said. "Most of this trade appears to be international, primarily to China."
Some primates on the list, and even some that didn't make the list, may already be extinct, researchers said. One called Miss Waldron's red colobus, for example, was removed from this year's list even though a live member of the species has not been seen for decades. It was bumped to make room for another red colobus thought to be on the verge.
"Miss Waldron's red colobus in Ghana and Ivory Coast, and Bouvier's red colobus in the Republic of Congo may already be extinct, while the Tana River red colobus in Kenya and Bioko red colobus in equatorial Guinea could be gone within the next 20 years," said Conservation International's Thomas Butynski.
The World's 25 Most Endangered Primates
Greater bamboo lemur (Prolemur simus), Madagascar
White-collared lemur (Eulemur albocollaris), Madagascar
Perrier's sifaka (Propithecus perrieri), Madagascar
Silky sifaka (Propithecus candidus), Madagascar
Eastern gorilla (Gorilla beringei), Democratic Republic of Congo, Rwanda, Uganda
Cross River gorilla (Gorilla gorilla diehli), Nigeria, Cameroon
Mt. Rungwe galago (an as yet undescribed form of the genus Galagoides), Tanzania
Tana River red colobus (Procolobus rufomitratus), Kenya
White-naped mangabey (Cercocebus atys lunulatus), Ghana, Ivory Coast
Sanje mangabey (Cercocebus sanjei), Tanzania
Bioko red colobus (Procolobus pennantii pennantii), Equatorial Guinea (Island of Bioko)
Black-faced lion tamarin (Leontopithecus caissara), Brazil
Buffy-headed tufted capuchin (Cebus xanthosternos), Brazil
Northern muriqui (Brachyteles hypoxanthus), Brown spider monkey (Ateles hybridus brunneus), Colombia
Horton Plains slender loris (Loris lydekkerianus nycticeboides), Sri Lanka
Miller's grizzled surili (Presbytis hosei canicrus), Indonesia (Kalimantan)
Pagai pig-tailed snub-nosed monkey (Simias concolor), Indonesia (Mentawai Islands)
Delacour's langur (Trachypithecus delacouri), Vietnam
Golden-headed langur (Trachypithecus poliocephalus poliocephalus), Vietnam
Western purple-faced langur (Semnopithecus vetulus nestor), Sri Lanka
Grey-shanked douc (Pygathrix nemaeus cinerea), Vietnam
Tonkin snub-nosed monkey (Rhinopithecus avunculus), Vietnam
Hainan black-crested gibbon (Nomascus nasutus hainanus), China (Hainan Island)
Sumatran orangutan (Pongo abelii), Indonesia (Sumatra)