Birds don’t become sick when exposed to the H1N1 influenza strains that caused the 1918 and 2009 global flu pandemics, a finding that suggests birds played no role in the spread of the pandemic-causing viruses, according to a new study.
Researchers injected the 1918 and 2009 H1N1 flu virus strains into chickens. After 18 days, none of the birds had developed flu symptoms or showed any signs of tissue damage. The 1918 H1N1 virus also didn’t cause disease in ducks, the study authors reported in the February issue of the Journal of General Virology.
via No Role Found for Birds in Swine Flu Pandemic – BusinessWeek.
Not sure about the logic here – some birds carry H5N1 without getting sick but can still be a vector for the disease to others