Caquetá Tití MonkeyDiscovered in 2010, Colombia's Caquetá tití monkey species may already be headed for extinction in the wild, according to the latest update of the International Union for Conservation of Nature (IUCN) Red List of Threatened Species, released this month. The Red List is a "critical indicator of the health of the world's biodiversity," according to IUCN. The list ranks species based on eight categories, ranging from "not evaluated" to "extinct." Assessed by scientists for the first time in 2012, the bushy-bearded Caquetá tití monkey is now considered critically endangered—at extremely high risk of extinction in the wild—due to widespread habitat destruction and fragmentation. Rural peoples in eastern Colombia, who rely heavily on pockets of remaining forest, sometimes hunt the animal for food, according to IUCN. (See pictures of endangered species from the 2011 list.) Of the 63,837 species evaluated for the 2012 Red List update, 19,817 are threatened with extinction, including about 41 percent of known amphibians and 25 percent of known mammals. The 2012 Red List was announced on the eve of the United Nations Conference on Sustainable Development, which took place this week in Rio de Janeiro, Brazil. (Related: "Rio+20 Brings Hope and Solutions Despite Weak Talks.") "A sustainable future cannot be achieved without conserving biological diversity—animal and plant species, their habitats, and their genes—not only for nature itself but also for all seven billion people who depend on it," IUCN director Julia Marton-Lefèvre said in a statement. "The latest IUCN Red List is a clarion call to world leaders gathering in Rio to secure the web of life on this planet." —Christine Dell'Amore

Photograph by Javier Garcia