The Tonkin Snub-nosed Monkey Rhinopithecus avunculus is among the World’s 25 most endangered primates. At present, the species is found only in few forest areas in Ha Giang and Tuyen Quang Provinces, north-east Vietnam with a total number not exceeding 250 individuals. | The tonkin Snub-nosed monkey Rhinopithecus avunculus population in the Quan Ba forest, north-east Vietnam: An identification of priority habitat for conservation