At 1.72 meters tall, dark and lean, Zhang Yong has demonstrated immense willpower in his job as guardian angel of Gahai Lake in Gannan Tibetan autonomous prefecture over the past 10 years.

The lake and its wetland, only 50 km away from Luqu town in Northwest China's Gansu province, occupying an area of 120 square kilometers, serves as a rest stop and hatching destination for tens of thousands of migratory birds from spring through fall.

But for much of the last century the land has become increasingly inhospitable to the birds because of severe droughts. In the late 1990s, the local government started to notice the degradation and started to carry out ecological protection efforts, establishing a conservation station in the area in 2003.