The infection of eight crows in Kyoto and Osaka prefectures with avian flu has raised concerns that wild birds that get near people may become potential vehicles for the virus.
While the central and local governments are conducting research on wild birds to learn the routes of infection, however, some experts say it is unlikely that bird flu is spreading among crows.
The infected crows found in Kyoto and Osaka are believed to have eaten the flesh of dead chickens at two flu-hit poultry farms in Kyoto Prefecture or consumed the droppings of infected chickens, said Masae Narusue, a researcher at the Wild Bird Society of Japan.
“Crows frequently enter poultry or cattle farms looking for food,” Narusue said, adding that crows are known scavengers that eat meat, vegetables and plants.
The Environment Ministry announced Wednesday that it will conduct research on crows that nest within 30 km of the first bird flu-infected poultry farm in Tanba, Kyoto Prefecture. The research area covers part of Osaka and Hyogo prefectures, according to the ministry.
But Takeshi Tobishima, of the ministry’s Office of Wild Life Management, said it is unlikely flu is spreading widely among crows in the area.
“Several crows were infected, but no large-scale outbreak among the birds has taken place,” Tobishima said. “The research is aimed at relieving public anxiety by examining whether there is a possibility of a further spread.”
In Kyoto Prefecture, where six infected crows were found, prefectural officials are collecting carcasses of wild birds and examining them for signs of infection, according to Fumio Fujii, a Kyoto prefectural official.
As of Wednesday, 1,771 wild birds — including 157 crows — were tested, though none other than the six was found to have been infected, Fujii said.
Thus far, the bird flu outbreak in Japan has been limited to Yamaguchi, Oita, Kyoto and Osaka prefectures.
But other prefectures nationwide are also carrying out random bird-flu tests on crows and pigeons, after the Environment Ministry ordered local governments to capture several living specimens for testing.
Katsuya Hirai, a professor emeritus at Gifu University and an expert of veterinary medicine, said this research is meaningful in assessing the level of infection among wild birds, adding that there is still the possibility of crows transmitting the virus to other birds.
“If there are more infected crows that are still alive, their droppings containing the virus may become the source of infection,” Hirai said.
But Toshihiro Ito, a professor at Tottori University and a member of the ministry’s bird flu advisory group, claimed there is little likelihood of more bird flu infection triggered by crows, because they do not next in highly crowded environments such as poultry farms.
Yutaka Kanai, a researcher at the Wild Bird Society of Japan and another member of the ministry’s advisory group, also said wild bird flocks disburse into pairs from spring to summer.
“So there will be less risk of crows spreading the virus,” Kanai reckoned.