Characteristics of important migratory stopover sites of black-necked cranes on the Tibetan plateau

Migratory stopover sites are essential for migratory birds as they travel between breeding and non-breeding grounds. The Black-necked Crane (Grus nigricollis), the only crane species that spends its entire life on the Qinghai-Tibetan and Yunnan-Guizhou Plateaus, serves as a flagship species in alpine wetland ecosystems. This species faces threats such as food shortages and habitat destruction. However, research on their stopover sites and habitat selection remains insufficient. We utilized satellite tracking data and remote sensing interpretation to extract the habitat types and areas of three main migratory stopover sites (Da Qaidam, Chaka Salt Lake, and Gyatong grassland) along two migration routes on the Qinghai-Tibetan Plateau: the southern foothills of the Qilian Mountains in Qinghai to the estuary of the Yarlung Tsangpo River and the Niyang River in Tibet, and Yanchiwan National Nature Reserve in Gansu to Linzhou, Tibet. In this study, a total of 37,452 valid GPS locations from 15 individuals during the spring and autumn migration periods were retained. Selection rates for each habitat type used by Black-necked Cranes at migratory stopover sites were calculated based on remote sensing interpretation. We then used principal component analysis to conduct habitat selection of the tracked cranes in these stopover sites. Black-necked Cranes preferred lakes, rivers, and swamps as stopover sites. They roosted in swampy areas and prairie meadows, and foraged in swamps and farmland. Mountains and building land were unused. Habitat selection favored areas away from roads and villages, with less human interference, high visibility, and good vegetation coverage. Prairie meadows around lakes and swamps are crucial for conservation.