"House crows pose a higher risk than magpies of spreading the virus," microbiologist Lo Wing-lok said, adding that crows congregate in populated areas looking for food and are not afraid of humans.

"This is a short-term, but necessary, precaution in this dangerous situation," said Lo, noting that if one house crow is infected, it is likely much of the flock will be too.

An AFCD spokesman said between 200 to 300 house crows had gathered in Shum Shui Po recently. He said the bird is an exotic invasive species that arrived in Hong Kong in the last few years.

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He said baits had been used to control excessive breeding of house crows and that more than 80 of the birds had been destroyed last year.

It will take several more days to confirm whether the dead house crow has been infected with H5N1 avian influenza, the spokesman said.

Lo said the Kowloon West area has seen an upsurge in crow activity for some years now.

Over the last few weeks, 122 dead birds have been picked up at public rental housing estates.

Lai On Estate in Sham Shui Po was cleaned as a precautionary measure after the dead crow was found.

Meanwhile, Saving Pet Birds Alliance spokesman Allan Shek announced that its planned march for Sunday against the backyard poultry ban will start at Central's Edinburgh Place and end at the SAR Government Headquarters at noon.