Black-necked cranes rest at a reservoir in Lhunzhub County, Lhasa, southwest China's Tibet Autonomous Region, Jan. 3, 2021. Black-necked cranes are often seen foraging and resting in the river valleys of Lhunzhub in winter. (Xinhua/Zhang Rufeng)

Black-necked cranes hover over a nature reserve in Lhunzhub County, Lhasa, southwest China's Tibet Autonomous Region, Jan. 3, 2021. Black-necked cranes are often seen foraging and resting in the river valleys of Lhunzhub in winter. (Xinhua/Zhang Rufeng)

Black-necked cranes are seen at a reservoir in Lhunzhub County, Lhasa, southwest China's Tibet Autonomous Region, Jan. 3, 2021. Black-necked cranes are often seen foraging and resting in the river valleys of Lhunzhub in winter. (Xinhua/Zhang Rufeng)

Black-necked cranes fly over a reservoir in Lhunzhub County, Lhasa, southwest China's Tibet Autonomous Region, Jan. 3, 2021. Black-necked cranes are often seen foraging and resting in the river valleys of Lhunzhub in winter. (Xinhua/Zhang Rufeng)

Black-necked cranes are seen at a reservoir in Lhunzhub County, Lhasa, southwest China's Tibet Autonomous Region, Jan. 3, 2021. Black-necked cranes are often seen foraging and resting in the river valleys of Lhunzhub in winter. (Xinhua/Sun Fei)

Black-necked cranes rest at a reservoir in Lhunzhub County, Lhasa, southwest China's Tibet Autonomous Region, Jan. 3, 2021. Black-necked cranes are often seen foraging and resting in the river valleys of Lhunzhub in winter. (Xinhua/Sun Fei)