Southern pig-tailed macaques in Indonesia's Bukit Barisan National Park are caught in the sights of 1 of 420 camera traps set up in seven tropical countries for a 2008-2010 study.
Generating some 52,000 pictures, this first ever global mammal study to use the traps uncovered pervasive trends in mammal decline, which underscore the importance of large protected areas, according to organizers.
Seen as facing a high risk of extinction in the wild by the International Union for Conservation of Nature (IUCN), the pig-tailed macaques are said to have suffered "very serious" habitat loss, mainly due to agriculture and logging, in parts of their range in Southeast Asia, according to the group.
The monkey's plight is no surprise. "The results of the study are important in that they confirm what we suspected," study leader Jorge Ahumada, an ecologist with Conservation International, said in a statement.
"Habitat destruction is slowly but surely killing our planet's mammal diversity."
(Also see "Pictures: Rare Antelope, Big Cats Caught by Camera Trap.")