Herring gulls, Canada geese, and mallard ducks were orally vaccinated with attenuated duck plague virus and challenge inoculated with virulent virus. Herring gulls were unfnected by either virus; they did not die or produce detectable antibodies. Geese did not produce antibody to attenuated virus and 11 of 12 died after immunity challenge. Mallard ducks were more resistant as 7 of 9 survived challenge inoculation with virulent virus. No correlation between mortality and antibody produced to attenuated virus vaccine could be observed.