Sulphur-crested Cockatoo - suffering from Psittacine Beak-and-feather Disease (Cacatua galerita). Brisbane, Queensland, Australia. / Cockatoo. This is caused by a circovirus that can be transmitted by contact at feeding sites, during nesting time, etc. It attacks the feather follicle and ultimately destroys its ability to produce feathers. Successive moults lead gradually to a total loss of plumage. The bird will finally die through inability to fly and thus find food. This bird shows symptoms of loss of ability to replace neck and crest feathers. Caused by a circovirus, PBFD affects many species of parrots (Psittacidae) and cockatoos (Cacatuidae). Widespread in northern and eastern Australia, New Guinea and nearby islands.