It has long been known that waterfowl are capable of migrating very long distances in the appropriate seasons. Bar-headed geese, one species that has been thought to be responsible for the spread of H5N1 around the world, are indeed capable of traveling up to 3000 miles from their breeding ground. Just last summer, scientists and conservationists together captured 50 wild geese in the Darkhad Valley of Mongolia, wrapped them to keep them still, took blood/oral/cloacal swabs, tagged the geese, and then released them back into their natural environment. One goose in particular was tagged with a yellow band and was labeled "E6." About a month ago (in December), an email from a man in India was received that reported the presence of the goose "E6" in his local area.
This "super migratory" ability of some migratory fowl may contribute to the spread of H5N1 to areas where there are no poulty, but poultry transport is a confounding factor.
see more: http://www.nytimes.com/2008/01/29/science/29gees.html?ref=science