Prevalence of BFDV in wild breeding Platycercus elegans

Pathogens can have a profound impact on the population dynamics of avian populations. Beak and feather disease virus (BFDV) is considered one of the few pathogens capable of causing extinction, because it predominantly infects the highly threatened order Psittaciformes, the signs of disease are severe, and mortality can be extremely high. Little is known about BFDV in wild populations, particularly its distribution among wild breeding birds. We investigated patterns of BFDV infection in family groups across three different subspecies of a common southeast Australian parrot (Platycercus elegans). We predicted that due to the high degree of contact, shared environment and high relatedness within family units, the prevalence of infection would be uniform. However, we found more non-infected breeding pairs than expected if there was random mating, whilst cases where both pair members were infected were observed less often than expected under random mating. When one pair member was infected, it was sex-biased, with males rarely infected. We found that parental infection status did not explain nestling infection status, suggesting that other infection routes (e.g. from the hollow or nest material) are likely. Future work is needed to assess transmission and behavioural mechanisms that explain patterns of infection among breeding birds.