It would be easy to think that a duck's feathers would soon become waterlogged so that it would sink, but in fact, ducks, geese and swans, as well as seabirds, have waterproof feathers, which enable them to swim and dive beneath the surface of the water Ducks create this waterproofing using the oil from the preen gland, near the base of the tail, which they spread through their feathers and the underlying dense layer of down with their bills. A layer of flat under their breast skin also helps to keep them buoyant. Different ducks feed in different ways, some dive, some upend and feed from the bottom of the lake or river while others 'dabble', stirring up the water with their feet to find food.
Fact file
There are about 160 different types of species of ducks in the world, and they are found on every continent except Antarctica. The duck in the picture is called a Pochard.
