What we found is that birds spread "preen oil" over their feathers to clean them. It also keeps them moist and flexible, improves their insulation capacities, and waterproofs them.
Preen gland, also called Uropygial, or Oil, Gland, in birds, an organ located on the back near the base of the tail. Paired or in two united halves, it is found in most birds.
Absent in ostrich, emu, cassowary, bustard, frogmouth, and a few other birds, the oil gland is best-developed in aquatic species, notably petrels and pelicans, and in the osprey and oilbird.
Feathers are the magic material that cover the bodies of all birds and help them to fly. But they're not just for flight.
Feathers are fantastic for keeping warm, which is why even flightless birds such as ostriches have them. And they have many other uses, including camouflage and display.
Learn more by checking these fifteen fun feather facts from Watchingbackyardbirds.com.