One of the most amazing and fascinating facts about birds, is their ability to travel thousands of kilometres every year to spend the winter in a warmer and nicer climate. It is most extraordinary that every year birds gather into flocks and fly away.
Most birds migrate to look for food - in the winter it is not easy to find 'summer' food - insects, fruits, seeds - in Europe, but there is plenty available in other parts of the world, where the climate is warmer. Migration makes the survival of species easier, although some birds do die during the flight.
To survive the migration, birds must be healthy, have a lot of fat and fresh feathers. After the end of breeding time, and before they start to migrate, birds go through a 'complete refurbishment'. The fat accumulates all over the bird's body, under their skin. The old and destroyed summer flight feathers fall out and new ones appear in their place.
Birds get much of the information from their surroundings while they migrate. Yet there are three basic sources of information for them - the sun, stars and the earth magnetic field. Birds observe the location of stars and sun during their flight, and they can feel the magnetic field with a special receptor placed just over their beak.