BEIJING, March 29 -- Four black-necked cranes fitted with satellite transmitters earlier this month are in good condition and remain in their winter habitats in Yunnan and Guizhou provinces.

    The transmitters were fitted to the cranes' backs and can automatically send signals to satellites to enable researchers to track them during their annual migration.

    The tracking project is a two-year collaboration between the Chinese Academy of Sciences (CAS) and the International Crane Foundation.

    Yang Xiaojun, a researcher from the Kunming Institute of Zoology, said the four transmitter-equipped birds, three in Dashanbao Nature Reserve in Yunnan and one in Caohai Nature Reserve in Guizhou, will soon fly northward to breeding grounds.

    The research team began tracking the first group of four black-necked cranes in February last year; however, they lost contact with two cranes halfway through their migration, while the other two reached their destination in the Ruo'ergai Wetland in Sichuan Province.

    The high cost of satellite tracking about US$5,000 per year for each bird means only a limited number of cranes can be chosen for the project.

    "We aim to better understand the black-necked cranes' migration routes and stopping points so that we can better protect them," Yang said.

    Yang said the black-necked cranes are a highly endangered species under first-class national protection, with an estimated population of less than 8,000, most of which live in China.

    Black-necked cranes are the only crane species living on plateaus. They were the last crane species to be found, discovered by scientists in 1876.

    An average adult black-necked crane is about 115 centimetres tall and weighs 5.35 kilograms.

    The cranes spend the winter in the lower elevations of the Qinghai-Tibet and Yunnan-Guizhou plateaus and fly long distances northwards to the high-altitude wetlands in Qinghai-Tibet Plateau for breeding during the summer months.

    Yang said as the cranes usually migrate over steep mountain ranges and remote valleys in western China, researchers still know very little about their migration routes and breeding areas.

    Yang said the public can follow the progress of the birds' migration route via the project website, which provides online maps and reports posted by members of the research team.

    (Source: China Daily)