One of the few waterfowl, the duck, was domesticated in the early 17th century. The monks in one of the sketes at first simply fed wild birds, and then learned to breed them, however, they kept the ducks exclusively in the water, because the bird swims perfectly.
Ducks are medium to relatively small birds. The order of ducks includes several genera of birds, these can be mergansers, river ducks, white-headed duck, or about 100 more species. These birds are both wild - they are called mallards, and domestic - drakes and ducks themselves.
Ducks have been bred by man since ancient times to obtain meat and eggs, the feather is used to make filler for pillows, mattresses and blankets, and is also used in a number of garments.
On land, in water and air
It is known that many birds can land on water and even spend some time on it, thanks to the air bag, which significantly reduces their specific gravity. But there are birds whose life is connected directly with water, to which ducks belong. In this regard, they have developed physiological adaptations for swimming and even diving.
Fat secret
The body of the ducks is somewhat flattened, which helps them to better stay on the water. The bones are hollow, lightweight. The plumage is waterproof, covered with an oily liquid, it is much thicker than that of most birds, especially in the lower body, which helps to resist getting wet. That is why the bird perfectly tolerates autumn weather and can swim in cold water for a long time. The fatty liquid is produced by a special gland located near the duck's tail.
Each time, before going into the water, the duck repeats the procedure for lubricating its feathers. The bird stands up and, as if shaking itself off, making muscular wave movements, while the feathers rise at the base and "fat" easily covers each feather. The same grease increases the volume of the duck's body, which also plays an important role in swimming. It has been experimentally proven that if a bird is deprived of lubrication or covered with a dense layer of an impermeable substance, for example, oil, the duck will not be able to swim.
The subcutaneous layer of fat in ducks is well developed, it is he who serves as a thermoregulator, preventing hypothermia at low water temperatures.
Fins-paws
The paws of these birds are also designed for swimming: three movable toes are directed forward and are connected by a special swimming membrane. In some species, the leather rim of each toe develops separately, this increases the overall surface of resistance and increases the power of the paw push against the water surface when rowing.
The paws' joints also serve to facilitate movement in the water, they are mobile and powerful. It should also be noted that the paws of ducks simply do not feel the cold and therefore do not freeze even at a sufficiently low water temperature.
