We surveyed south polar skuas (Catharacta maccormicki Saunders) in Antarctica for antibodies to a series of viral agents using blood serum and cloacal swabs from 124 adult skuas. There were no ticks on the subjects and we were unable to isolate virus from any individual. Skuas, however, were seropositive to some avian viruses: 16.9% (20/118) had antibodies to infectious bursal disease virus and 10.5% (11/105) were seropositive for Newcastle disease. We found 1.0% (1/98) had antibodies to avian influenza, no evidence of egg drop syndrome (0/48), but 27.8% (10/36) had antibodies to flaviviruses. Clearly south polar skuas encounter a variety of pathogens either in Antarctica or during their migration in the non-breeding season. There was no evidence of disease in skuas, but the presence of antibodies to pathogens indicates the need to continue to search for the origins of these immunological challenges.
