Wildlife experts have been left baffled by the deaths of 178 bar-headed geese, a second-class State-protected animal.

Since May 6, carcasses have washed up on the banks of Qinghai Lake in northwest China's Qinghai Province.

Staff of the Qinghai Lake Nature Reserve first discovered 19 dead geese on the western banks of Bird Island last Wednesday. Four days later, more dead geese were discovered on the island and in nearby areas.

"Initial lab studies have been done and we have ruled out bird flu and other infectious diseases," said Li Sandan, director of the Qinghai Forestry Bureau. But he added that the cause of death remains unknown.

There have been no reports of similar findings in relation to other birds that inhabit the area such as the brown-headed gull and the cormorant.

"The bar-headed goose migrates across the Himalayas to spend winters on the Indian plains and it breeds on the Qinghai-Tibet Plateau in May and June," said Wen Bo, Chinese director of Pacific Environment, a US-based non-governmental organization, which supports the growth of Chinese environmental groups. "Human activity has drastically changed the natural living environment of wild birds thereby affecting their breeding patterns," added Wen.

Covering an area of 4,232 square kilometers on the Qinghai-Tibet Plateau, Qinghai Lake is China's biggest saltwater lake, and is home to a host of rare and endangered wildlife species including the bar-headed goose, black-necked crane and wild swan.

But their numbers have decreased rapidly over the years.

Wen blames the use of pesticides and poaching for the mass destruction of migrant birds.

(China Daily May 10, 2005)