 Red @-@ billed choughs can also carry mites , but a study of the feather mite <unk> <unk> , acquired by young birds a few months after fledging when they join communal roosts , suggested that this parasite actually improved the body condition of its host . It is possible that the feather mites enhance feather cleaning and deter pathogens , and may complement other feather care measures such as sunbathing , and anting — rubbing the plumage with ants ( the formic acid from the insects deters parasites ) . 
