One of the few waterfowl - the duck - was domesticated in the early 17th century.
Monks in one of the monasteries at first simply fed wild birds, and then learned to breed them, although they kept ducks exclusively on the water, because the bird swims perfectly.
Ducks are medium or comparativelySmall size. The group of ducklings includes several genera of birds, it can be crumbs, river ducks, ducks or even about 100 species. There are these birds as wild - they are called mallards, and domestic - drakes and ducks.
Duck man is cultivated from ancient times for meat and eggs, the pen goes on making fillers 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 onWater and even spend some time on it, thanks to an air bag that significantly reduces their specific weight. But there are birds whose life is directly related to water, to which the ducks belong. In this regard, they have developed physiological adaptations for swimming and even diving.
The body of the ducks is somewhat oblate, which helps themBetter to stay on the water. The bones are hollow, light. The plumage is waterproof, covered with oily liquid, it is much thicker than most birds, especially in the lower part of the trunk, which helps to resist wetting. That is why the bird perfectly tolerates the autumn weather and can swim for a long time in cold water. Fat liquid produces a special gland, which is located near the tail of the duck.
Every time before you go into the waterThe procedure for the lubrication of its feather duck repeats again. The bird rises and shakes as it does muscular wave movements, while the feathers rise at the base and "fat" easily covers each feather. The same fatty grease increases the body volume of the duck, which also plays an important role in swimming. It has been experimentally proved that if a bird is deprived of a lubricant or covered with a dense layer of impenetrable substance, for example, with oil, a duck will not be able to swim.
The subcutaneous fat layer of ducks is well developed, it serves as a thermoregulator, preventing subcooling at low water temperatures.
Paws of these birds are also designed for swimming: Three moving fingers pointing forward and connected by a special swimming membrane. In some species, the leather rim of each finger develops separately, this increases the overall surface of the resistance and enhances the power of the paw thrust against the water surface when rowing.
The joints of the paws are also used forFacilitate movement in the water, they are mobile and powerful. It should also be noted that the paws of the ducks simply do not feel cold and therefore do not freeze even at a sufficiently low temperature of the water.