Black-headed gulls that migrate from Siberia to Kunming, China's "city of eternal spring," each winter, are free from bird flu virus, zoologists have found.

Experts with a laboratory based in this capital of the southwestern Yunnan Province declared late on Monday they had found no bird flu virus in any of the 60 odd gulls caught randomly when hovering above the city.

The laboratory, which tests tropical and subtropical animals for viruses, has tested the birds' blood serum, saliva and excrement and has not found any H5 virus, according to Yang Zhimin, an official in charge of bird flu control and prevention in the province.

The laboratory had been closely monitoring migratory birds since bird flu outbreaks were first reported in Vietnam, said Zhang Nianzu, a researcher with the lab.

Zhang said their sampling tests would continue, as migratory birds, particularly waterfowls, were suspected by many experts to be potential virus carriers.

Black-headed gulls are known in China as red-beaked gulls. The birds first appeared in Kunming in 1985 and about 30,000 of the species fly here for winter each year.

They settle down in the grass alongside Dianchi Lake in suburban Kunming at night, and fly to the downtown areas during daytime in search of food.

The birds, with greyish-white feathers, strong wings and well-proportioned bodies like pigeons, have received a warm welcome among locals and tourists alike, who gather in large numbers each day to make a special trip to feed the birds.

In 1995, Kunming residents erected a special monument in a downtown park to commemorate the migratory gulls, with hopes that man would always be in harmony with the beloved gulls.

(Xinhua News Agency February 10, 2004)