The Bureau of Animal and Plant Health Inspection and Quarantine (BAPHIQ) under the Council of Agriculture (COA), in collaboration with the wild bird societies of Taipei City and Tainan City, implanted GPS sun-powered transmitters into three wild ducks in April.

Two of the ducks are from Taipei City's Huajiang Wild Duck Nature Park, and one from Tainan City's wetlands in Sihcao. They were chosen because of their good health, and for their medium build which is ideal for fitting the devices, explained Huang Kwo-ching, BAPHIQ director of Animal Health Inspection.

According to Huang, in the past, only educated guesses could be made about migratory patterns, which were very much still a mystery.

"With the use of GPS, we are thus implementing a scientific approach to gain conclusive evidence," he said.

The GPS is a satellite navigation system that provides global geo-spatial positioning via electronic receivers that determine location, speed and direction. Receivers can also be used to calculate the precise time as a reference for scientific experiments.

The BAPHIQ has two main hypotheses on the flight routes of the migratory birds. Starting from Russia's Siberia region where Huang says is a main congregation spot for migratory birds, these reach Taiwan either by flying along the waters off the eastern coast of China, or via Japan and Korea. Some keep going south to the Philippines.

But Huang said recent GPS readings placed the Taipei ducks in Korea. He expects them to be back on the island in September to spend the winter.

As for the Tainan duck, both the southern city's wild bird society and the BAPHIQ are unclear on its whereabouts. "It is probably still on the island and is dwelling in a sun-deprived area, which prevents us from picking a signal as the GPS implant runs on solar energy," said Huang.

Another use for the GPS devices is to track possible infections of avian influenza or "bird flu," a contagious animal disease caused by a virus that normally affects only birds and, on rare occasions, pigs.

In recent years, however, the virus has also infected humans, with the highly pathogenic H5N1 strain of the virus causing the largest number of cases of severe disease and death. No vaccine is ready for commercial production.

While the role of migratory birds in the spread of avian influenza is not fully understood, mass die-offs in migratory birds infected with the disease suggest that it is possible that they are directly spreading the highly pathogenic form of the virus.

The first instance of such mass deaths was reported in April 2005 from Qinghai Lake in central China, where 6,345 birds died. Research reported by the World Health Organization (WHO) suggests that the virus may be carried along winter migratory routes. Other instances have occurred in areas adjacent to Siberia, Northern Mongolia, and Croatia.

Taiwan reported the detection of avian influenza on Oct. 20 of 2005 in a cargo of exotic birds smuggled from China, but no human cases have been reported. Huang reiterated that Taiwan is free of the disease.

If the GPS-fitted ducks do come back with bird flu, while the positioning system cannot pinpoint the precise location of disease transmission, the particular virus strain can be matched against other areas with reported cases of the same strain to narrow down the possible locations, said Huang.

According to the WHO, since 2003 until May 24, 2007, there have been five reported cases of human deaths to avian influenza (5HN1) in Azerbaijan, seven in Cambodia, two in Iraq as well as in Lao People's Democratic Republic, one in Nigeria, four in Turkey, 15 in China, 14 in Egypt, 17 in Thailand, 42 in Vietnam, and 77 in Indonesia.

The latest human death to H5N1 was reported on May 24 by health authorities in Indonesia, where a five-year-old girl from the Central Java province died May 17.