Surveys at a Tibetan antelope Pantholops hodgsonii calving ground adjacent to the Arjinshan Nature Reserve, Xinjiang, China: decline and recovery of a population

Females in most populations of chiru or Tibetan antelope Pantholops hodgsonii migrate each year up to 350 km to summer calving grounds, and these migrations characterize the Tibet/Qinghai Plateau. We studied the migratory chiru population at the Ullughusu calving grounds southwest of the Arjinshan Nature Reserve in Xinjiang, China. The 750-1,000 km(2) of suitable habitat at Ullughusu is at 4,500-5,000 m With sparse vegetation. We used direct methods (block counts, vehicle and walking transects and radial point sampling) and an indirect method (pellet counts) during six summers to assess population density. We also witnessed and stopped two major poaching events, in 1998 and 1999 (103 and 909 carcasses, respectively). Surveys suggested a drop in population density from 1999 to 2000. Poaching was not seen during summer monitoring after 1999, and surveys in 2001 and 2006 suggest that the population density is stable or recovering. We compare the Ullughusu calving grounds with those in the western Kunlun and discuss possible routes for migrating females.