We surveyed all known wintering areas of the Black-necked Crane (Grus nigricollis) in Zhigatse Prefecture of the Tibet Autonomous Region during three winters. Our surveys confirm that Zhigatse Prefecture is the most important wintering area for the species, accounting in some years for as much as 39% of the estimated world population. Counts ranged from a high of 4240 cranes in January 2007 to a low of 2636 in February 2009. Chick recruitment (chicks/100 cranes) ranged from 8.2 (January 2010) to 11.3 (January 2007). The highest concentration of cranes during all three surveys occurred on the 60 km stretch of the Yarlung Tsangpo (River) between Lhaze and Phuntsoling. To evaluate potential impacts of the Xietongmen Copper Mine, we monitored wintering crane numbers prior to mine installation in an intensive study area located between the Shab Chu Valley and the city of Zhigatse. Our surveys recorded on average 820 ± 83 cranes (SE; n = 8) in this area. With the installation of the mine at a location ~50 km west of Zhigatse, increased traffic and development on the north side of the Yarlung River will likely result in a shift in crane distribution away from the north side, to nearby suitable habitats. Based on our survey results, we recommend three areas hosting high numbers of cranes in the vicinity of the mine be added to the Yarlung Tsangpo Middle Reaches Blacknecked Crane Nature Reserve. These areas are Nierixiong and Jiaqingze Villages in Nierixiong Xiang and the Shab Chu Valley.

We investigated collisions with power lines by Black-necked Cranes (Grus nigricollis) and Barheaded Geese (Anser indicus) along the Yarlung Tsangpo River in the Tibet Autonomous Region during two winters. Three segments of a 35 kV transmission line were surveyed each winter for injured and dead birds. Injured birds disappeared within five days of their initial detection; most dead birds encountered had been scavenged. We recorded two dead geese on transects and two injured geese and two dead cranes adjacent to transects. We found a higher incidence of bird strikes along power line segments close to roosting and foraging areas. We recommend that power lines, new or old, located in the flight path from nocturnal roosts, near important foraging areas or crossing the mouths of important agricultural valleys should be marked with colored and/or reflecting devices that have been proven to reduce crane and goose collisions.

Summary Four of China’s six wintering populations of “grey” geese Anser spp. declined during the last decade. In contrast, the Bar-headed Goose A. indicus wintering population in China’s Tibet Autonomous Region more than doubled. During six surveys in Tibet over a 27-year period (1991/92 to 2017/18 winters) we documented an annual growth rate of 6.8% in the Bar-headed Goose population – an increase from approximately 10,100 to 68,100 birds. We propose that in addition to the cessation of hunting, the population growth of Bar-headed Goose is being driven by changes in agricultural land use patterns in Tibet, the establishment of protected areas on the wintering and breeding grounds, and the impacts of climate change across the Tibetan Plateau. Consistent with this hypothesis, the sown area of winter wheat in Tibet has increased and geese have shifted from primarily feeding in crop stubble to planted winter wheat fields. We also found that the most rapid population growth coincided with a 1998 climate regime shift across the Tibetan Plateau resulting in warmer temperatures, an increase in net precipitation, the appearance of new lakes and changes in the water levels and surface area of historical lakes. We suggest that warmer temperatures and high-quality forage on the south-central Tibet wintering grounds may be enhancing over-winter survival, while on the breeding grounds the expansion of lakes and wet meadows is augmenting breeding and brood-rearing habitat.