Migratory birds gather for food in Qiongxi Wetland Park in Hongyuan county after a spring snow. It's at the southeastern edge of the Qinghai-Tibet Plateau. Among the birds, the endangered black stork is under China's highest level of national protection. Black storks are an important environmental indicator because they live only in environments where the water quality is good. The black stork has been seen in Hongyuan county for many years, indicating an improved environment.