Ключевые слова: animal, animals, aquatic, avian, beak, behavior, bill, bird, brown, cleaning, duck, ecology, ecosystem, fauna, feather, feathers, fowl, grooming, hygiene, mallard, natural, nature, neck, one, park, plumage, preen, preening, quack, routine, single, waterfowl, wild, wildlife, wing, wings, yellow,