One of the few water birds - duck - was domesticated in the early 17th century.
Monks in one of the monasteries at first just to lure in wild birds, and then learned how to breed them, however, held only ducks on the water, as the bird flies perfectly.
Ducks - a bird of average or relativelysmall size. duck squad includes several genera of birds, it may be mergansers, dabbling ducks, Savka, or even about 100 species. There are these birds as the wild - their names mallards and domestic - drakes and ducks itself.
Divorced man duck since ancient times for their meat and eggs, the pen is used to make the filler for pillows, mattresses and blankets, as well as used in a number of garments.
On land, in water and air
It is known that many birds can land onwater and even spend some time on it, because of the air bag, greatly reduces their weight. But there is a bird whose life is connected directly to the water, to which the ducks are. In this regard, they have developed physiological adaptations for swimming and even diving.
The body is flattened several ducks that helps thembetter to stay on the water. The bones are hollow, lightweight. The plumage is waterproof, covered with an oily liquid, it is considerably thicker than most birds, especially in the lower part of the body that helps to resist wetting. That is why the bird perfectly brings bad weather and can fall for a long time to swim in cold water. Oily liquid produces a special gland that is located near the tail ducks.
Every time, before heading into the watertheir feathers duck lubrication process repeats again. The bird gets up and shakes like, making muscular wave motions, while feathers are raised at the base and "fat" easily covers every feather. This also increases the amount of fat the body grease duck, which also plays an important role in navigation. It is experimentally proved, that if a bird deprive grease or cover the dense layer of impermeable material, for example, oil, duck can not swim.
The subcutaneous layer of fat ducks are well developed, that it serves as a thermostat to prevent hypothermia at low water temperatures.
The feet of these birds are also intended for swimming: three movable fingers pointing forward and joined the special swimming membrane. In some species develop leather fringe of each finger individually, it increases the overall resistance of the surface and increases the power of the legs push the water surface while rowing.
paw joints also serve to structure theirfacilitate movement in the water, they are mobile and powerful. Also it should be noted that the duck legs just did not feel the cold, and therefore do not freeze even at a sufficiently low temperature of the water.