A brown pelican preening, reaching with its beak to the uropygial gland (preen gland) near the base of its tail. Preen oil from the uropygial gland is spread by the pelican's beak and back of its head to all other feathers on the pelican, helping to keep them water resistant and dry. Note adult winter breeding plumage in display, with brown neck, red gular throat pouch and yellow and white head. La Jolla, California, USA