Based on a six-day bird monitoring operation which covered over 1,300 km around the lake in northwest China's Qinghai Province in late April, the monitoring staff observed 48 species of water birds totaling 31,300 in number. According to the Qinghai Lake National Natural Reserve's administration, there were about 11,000 birds in the same period last year. 

The observed birds included rare species such as black-necked cranes and black storks, which are under first-class state protection; and white spoonbill, whooper swan and horned grebe, which are under second-class state protection. 

Officials with the local nature reserve administration said the water birds entered breeding season in late April. In some habitats, birds have finished nesting. 

"The rising water level of the Qinghai Lake in recent few years has expanded areas of its surrounding shallow wetlands, which improved the general population structure of water birds," said Hou Yuansheng, an official with the Qinghai Lake National Natural Reserve's administration. 

The lake has been expanding since 2005. According to the Qinghai hydrology and water resources investigation bureau, the water level rose to 3,195.41 meters at the end of last year. Statistics show the area where the lake is located saw average precipitation of 504 millimeters in 2018, 30 percent higher than that between 1981 and 2010. 

Experts said the rising level of the lake could help increase the area's humidity and temperature, which provide a better habitat for the wildlife. 

Qinghai Lake is an important ecological barrier in northern China and a key stop for migrant birds from Central and East Asia. Dubbed as the "most beautiful lake in China", it plays an important role in the ecological security of the Qinghai-Tibet Plateau.