XINING, April 6 (Xinhua) -- A flock of black-necked cranes, which has listed under the top protection of the state in China, have been spotted in in a grassland in northwest China's Qinghai Province.

The first group of the black-necked cranes began to arrive in mid-March at a vast grassland in Tibetan Autonomous Prefecture of Yushu. The biggest group consisted of 271 cranes, according to local forestry authorities.

"From mid-March to April 4, an average of more than 230 cranes flocked to the grassland each day," said Tsultrim, a local official in charge of environmental protection and forestry.

The cranes usually fly to the grassland in late March, and leave by the end of October.

Black-necked cranes inhabit meadows, wetlands, and lakes at an altitude of 2,500 to 5,000 meters. They mainly live in the highlands of China, India, Bhutan and Nepal.

With an estimated population of around 10,200, the species is classified as vulnerable by the International Union for Conservation of Nature.