Female Mallard frolicking on the water? Not a frolic -- she was having a bath. Standing on a submerged rock, she dipped her bill and dabbed her feathers with water. Later she swam to the shore and tidied herself on the sunny grass. Ducks such as Mallards (Anas platyrhynchos) have a preen gland that produces oil. Using the bill, they smooth their feathers and spread the preen oil to condition them. All birds need to maintain their plumage . . . re-position feathers, interlock feather barbules that have become separated, and remove parasites from their body or plumage.
