As the year draws to a close, millions of wild birds have flown to their wintering sites across, Asia, Africa, Europe and the Americas without the widely predicted outbreaks of H5N1 bird flu associated with their migration routes.

"The most obvious explanation is that migrating wild birds are not spreading the disease," said Dr Michael Rands, Director & Chief Executive of BirdLife International.

"Migratory wild birds were blamed for spreading bird flu west from Asia, yet there's been no spread back eastwards, nor to South Asia and Africa this Autumn. The limited outbreaks in eastern Europe are on southerly migration routes but are more likely to be caused by other vectors such as the import of poultry or poultry products. The hypothesis that wild birds are to blame is simply far from proven," said Dr Rands. "Wild birds occasionally come into contact with infected poultry and die: they are the victims not vectors of H5N1 bird flu."

BirdLife maintains that better biosecurity is the key to halting the spread of bird flu. In particular, BirdLife is urging governments and relevant agencies to concentrate their efforts on the poultry and cage bird trades and to ban the movement of poultry and poultry products from infected areas, and restrict the international movement of captive birds in trade.

BirdLife is also strongly urging governments to ban the use of untreated poultry faeces as fertiliser and feed in fish-farms and in agriculture. Domestic bird waste is widely used as food and fertiliser in fish farming and in agriculture, yet infected poultry are known to excrete virus particles in their faeces.

The use of untreated faeces in fish farming was recently described by the United Nation's Food and Agriculture Organization as a “high risk production practice”. Russian fish farms have begun using chicken faeces as fish farm fertiliser, and this practice is employed in Eastern Europe where poultry faeces are also spread onto agricultural land. The Government of Vietnam has warned local residents against the risk of dumping tonnes of chicken faeces into rivers and lakes as fish food; one boy has died of bird flu after swimming in a river where infected chicken carcases were discarded. This October, Mute Swans died at fish farms in Croatia and Romania.

"Implementing measures like these are proven to work," says Dr Rands. "For example, Malaysia and South Korea both experienced bird flu outbreaks through importing infected poultry products, but stamped the disease out and have remained disease free through improved biosecurity. In the mean time, hundreds of thousands of waterbirds have arrived to winter in, or migrated through South Korea, and many migrant waders have passed through Malaysia."

"Better biosecurity is the key to controlling the disease's spread," said Dr Rands. "But the virus can rapidly mutate, so it's important to monitor wild bird populations to look for evidence of new strains arising."