|Photo from: http://shelleypenne0.wix.com|
Some ways birds maintain feather quality is through water, dust, and sun bathing. Instinct to sunbathe is not always to warm the body. Like humans they probably enjoy a few rays but their main reasons for sunning is probably to keep their feathers in top shape.
Most birds have a preen gland or uropygial gland at the base of the tail. With their beak, birds realign the barbs correctly, remove any dirt or parasites and apply preen oil. If the bird sunbathes the oil is exposed to the ultraviolet light from the sun. Then the uropygial gland secretions convert to an active form of vitamin D which is ingested with the next preening. This may explain in part why some birds sunbathe.
Types of Bird feathers http://bit.ly/w0U1M6
Dirt baths help birds stay clean http://bit.ly/rJR7Ex
Why birds molt http://bit.ly/rGaqRL
Why do bluebirds bathe more than cardinals? http://goo.gl/ZdYRS
Birds Don't Sweat: http://goo.gl/zerp7