PARIS - Avian flu, believed to be carried south from China and Siberia by migrating wildfowl, threatens to push some of the world's rarest birds towards extinction, conservation groups said on Thursday.
Experts also voiced concern that any attempts to cull wildfowl suspected of carrying the disease could simply scatter the virus more widely by driving flocks away from their normal routes, doing more harm than good.

Britain's Royal Society for the Protection of Birds (RSPB) has identitified species it believes are particularly at risk.
Birds such as the aquatic warbler, the Dalmatian pelican, the marbled teal, the slender-billed curlew and the spoon-billed sandpiper all fly south from Siberia and could come into contact with migratory wildfowl carrying the deadly H5N1 virus.
"These are birds that are already endangered, and any further pressure either from the virus itself or misguided attempts to control it through culling would be disastrous," RSPB spokesman Andy Evans told Reuters.
"Bird flu could drive the slender-billed curlew to extinction -- there are very few specimens left and the virus could just be enough to push it over the edge," said Ward Hagemeijer of conservation group Wetlands International
In Asia, the best documented case is that of the wild bar-headed goose. It has been estimated up to 10 percent of the world population died in a recent bird flu outbreak in China.
The H5N1 virus is particularly deadly for chickens and can wipe out a flock within hours. But some wild water-birds such as ducks and geese can harbour the virus for long periods, most of the time showing no symptoms or becoming ill.
Whilst any bird can in theory become infected, wildfowl are the primary carriers, with many species flying from Siberia over the Middle East to Africa at the onset of winter.
CONCERN OVER AFRICA
The H5N1 virus has now been detected in Romania and Turkey, and is suspected in Greece. Scientists say this reinforced the theory that migrating birds are carrying the disease south.
Conservationists said the bald ibis, which winters along the southern Mediterranean coast, could also be threatened.
The same goes for the red-breasted goose, already classified by Birdlife International as vulnerable with most of the 88,000 birds left wintering at only five roost sites on the Black Sea.
In Africa, conservationists are concerned about areas like the Sudd marshes in Sudan, the biggest inland wetland in the world and a huge magnet for migratory birds. Its remoteness adds to the difficulty in surveillance and monitoring there.
If the virus spread further into continental Europe, wetland areas with high bird populations like the Camargue in southern France could be the first place it shows up, Hagemeijer added.
But all agreed that mass culls of wild birds were not the answer to controlling the spread of the disease.
"Species that die from the virus are unlikely to carry it long distances, so the reservoir is likely in a species that is showing few or no clinical signs," said Adrian Long, spokesman for Birdlife International in Britain.
"Without knowing which species are the reservoir, you cannot even begin to design a culling programme”.”
And it could just exacerbate the problem.
"Culling wild birds in areas affected by bird flu is unlikely to be helpful and may make matters worse by dispersing infected birds," the RSPB said.