A grey heron hovers over the reeds on a wetland in the Shahu Scenic Area in Yinchuan, capital of northwest China's Ningxia Hui Autonomous Region, April 16, 2014. In April, the 80 square kilometers of wetlands in the Shahu Scenic Area in suburban Yinchuan has become home to more than 1.2 million migrating birds. (Xinhua/Peng Zhaozhi) 

A grey heron takes off from a wetland in the Shahu Scenic Area in Yinchuan, capital of northwest China's Ningxia Hui Autonomous Region, April 16, 2014. In April, the 80 square kilometers of wetlands in the Shahu Scenic Area in suburban Yinchuan has become home to more than 1.2 million migrating birds. (Xinhua/Peng Zhaozhi) 

A grey heron lands on a wetland in the Shahu Scenic Area in Yinchuan, capital of northwest China's Ningxia Hui Autonomous Region, April 16, 2014. In April, the 80 square kilometers of wetlands in the Shahu Scenic Area in suburban Yinchuan has become home to more than 1.2 million migrating birds. (Xinhua/Peng Zhaozhi) 

Two grey herons hover over a wetland in the Shahu Scenic Area in Yinchuan, capital of northwest China's Ningxia Hui Autonomous Region, April 16, 2014. In April, the 80 square kilometers of wetlands in the Shahu Scenic Area in suburban Yinchuan has become home to more than 1.2 million migrating birds. (Xinhua/Peng Zhaozhi) 

Two mandarin ducks swim in a wetland in the Shahu Scenic Area in Yinchuan, capital of northwest China's Ningxia Hui Autonomous Region, April 16, 2014. In April, the 80 square kilometers of wetlands in the Shahu Scenic Area in suburban Yinchuan has become home to more than 1.2 million migrating birds. (Xinhua/Peng Zhaozhi)