 Pelicans swim well with their strong legs and their webbed feet . They rub the backs of their heads on their preen glands to pick up an oily secretion , which they transfer to their plumage to waterproof it . Holding their wings only loosely against their bodies , pelicans float with relatively little of their bodies below the water surface . They dissipate excess heat by gular flutter – rippling the skin of the throat and pouch with the bill open to promote evaporative cooling . They roost and loaf communally on beaches , sandbanks and in shallow water . 
