Poultry vs. Migratory Birds

As bird flu spreads across Europe and Africa, the question of the vector remains unanswered. One camp notes that poultry farms have been the hardest hit, while backyard chickens who are more exposed to migratory bird routes remain surprisingly healthy. Bird flu, they say, follows domestic fowl along agricultural trade routes, not wild birds on their migratory routes. See, for example, GRAIN's "Fowl play: The poultry industry's central role in the bird flu crisis".

The other camp documents the migratory paths along which H5N1 has spread--from China north to Siberia and then west to either Europe or Africa. A typical story is Unless we act now, bird flu may win in the International Herald Tribune:

For at least a decade H5N1 has circulated among a small pool of migrating birds, mostly inside China, and occasionally broken out in other animals and people. Last May, however, more than 6,000 avian carcasses piled up along the shores of Lake Qinghai, in central China, one of the world's most important bird breeding sites. Most of the dead included species that hadn't previously evidenced influenza infection.
The Lake Qinghai moment was the tipping point in the bird flu pandemic. The virus mutated, evidently becoming more contagious and deadly to a broader range of bird species, some of which continued their northern migration to central Siberia. By June, Russia's tundra was, for the first time, teeming with H5N1-infected birds, intermingling with southern European species that became infected before flying home, via the Black Sea.