Abstract: The geographic range of Rhinopithecus bieti is in the Trans-Himalayas, bounded by the upper Yangtze River to the east and the upper Mekong River to the west, and between 26°14′N and 29°20′E. We made several surveys on the status and habitat of R. bieti from 1999 to 2002. Reportedly, the total population was estimated to be 1 200 —1700, belonging to 13 groups. We found four groups of monkeys that were not previously reported, and 5 groups might have been extinct. The north- ernmost group at Mangkang had divided into two groups. The exact ranges of other groups had shifted more or less. From the northernmost, Mangkang in Tibet, to the southernmost, Yunlong in Yunnan, and with the elevation decreasing there are several vegetation types where monkeys can utilize. Based on rigorous standard, only two monkey groups are not subjected to effects of small group, and the habi- tat corridors, which are subjected to threats of logging, grazing, and mining, etc., are severely damaged. Comparing the present data to the data collected ten year ago (except new founding group), the status of the species is not very optimistical. The total number of R. bieti declined 32 %, 5 out of 14 groups are extinct, 4 groups declined, other 4 groups stay same or declined lightly, there are only 1 group showed growth trend. The five extinct groups have rung an alarm bell for the fate of this species. To protect existing corridors and restore the vanished or disturbed corridors should be one of the vital steps for the conservation of the species.

Key words: Rhinopithecus bieti; Population size; Threat factor; Habitat corridor