BEIJING, May 5 (Xinhua) -- A black-necked crane, coded V021, has had a year to remember.

Rescued near a national nature reserve in southwest China's Yunnan Province last spring, the young crane had been injured. It was left alone during its flock's migration journey.

Wu Heqi, a researcher from the Chinese Academy of Sciences (CAS), tagged it after a week in care to monitor its flight speed and movement by satellite, and bid farewell to it.

The "V" on the tag stands for victory, symbolizing hopes for its successful return to the wild and to its migration destination, Wu explained.

In China, black-necked cranes migrate to breeding grounds in the second half of March and arrive at wintering grounds from mid-October to November. They are first-class protected animals in China and the world's only cranes growing and breeding on the plateau.

The number of cranes at the nature reserve in Yunnan has steadily increased in recent years with conservation efforts. Crane guards, monitoring facilities and electronic fences in the reserve protect their wintering grounds.

V021 was the first black-necked crane monitored by Wu's team using satellite tagging technology to help researchers accurately track the crane's flight altitude, speed, ambient temperature and migration routes.

Since 2004, the team has tracked hundreds of birds, including more than 10 black-necked cranes, with satellite tags.

This tracking shows several national nature reserves in southwest China's Guizhou and Yunnan provinces provide stopovers and destinations on one of migration routes of black-necked cranes, Wu said.

The nature reserve in Guizhou was V021's wintering ground last year. It arrived in November.

This April, V021 arrived at a wetland in southwest Sichuan Province, a main terminal for black-necked cranes in summer. Last year, it enjoyed the summer in another national nature reserve in northwest Qinghai Province.

The reserve is a main breeding ground and habitat for black-necked cranes. Once a resort, in April 2018, it was permanently closed to public, so as to further protect its waterways and grassland.

Recent years have seen an obvious improvement in the reserve's ecological environment, with lake water becoming clearer and vegetation recovering. And the number of black-necked cranes breeding there has also increased.

The continuously improving ecology may also be the reason why V021 chose to stay here for over a month, said Zhang Tongzuo, a researcher at the Northwest Institute of Plateau Biology under the CAS.

Reserve staff and researchers in China are exploring new ways to provide better protection to black-necked cranes. In recent years, Qinghai has continued to promote the wildlife protection and nature reserve and wetland construction, contributing to greater biodiversity and the growing population of the cranes in the province.