Chimpanzee hunters drive endangered monkeys to the brink.

Not people hunting chimpanzees, Scientific American reports, but chimpanzees hunting monkeys:

According to a study published May 9 in the American Journal of Primatology, this is the first documented case of a nonhuman primate significantly overhunting another primate species.

(The taxonomy of Ugandan red colobus monkeys is in dispute. Some scientists consider them a species, Procolobus tephrosceles, whereas others identify them as a subspecies, P. rufomitratus tephrosceles.)

The study examined nearly 33 years of primate census data (covering 1975 to 2007) and found that the endangered Ugandan red colobus monkey population dropped 89 percent during that time, mainly as a result of being hunted by common chimpanzees (Pan troglodytes).