‘Sunbathing’ is used by some birds as part of their routine feather maintenance and is most commonly seen by Garden BirdWatchers in Blackbirds and Robins. The birds invariably adopt a posture in which the body feathers are fluffed up and one or both wings are held out from the body, with feathers spread. It is thought that using the sun in this way does two things. It both helps the preen oil to spread across the feathers and drives parasites out from within the plumage. Some of these parasites feed on the feathers themselves and all are highly specialised, with many only found on a single species of bird.