Undoubtedly, in flights of great importance instinct, that is innate, inherited the ability to a specific behavior. An example of instinct in birds: nobody teaches the bird to build a nest, but when she first starts to build, it makes it like all birds of its kind. Some of the first birds fly away young, and then the old birds. Consequently, young nobody shows you the way for the winter, they somehow from a birth the "know" yourself.
Many of the experiments confirm that birds leads "instinct".
During one of these experiments a group of storks were taken from their nests shortly before the time of the fall flight and moved to another place. With this new place, they had to fly in another direction in order to reach their winter quarters. But when the time came, they flew in the same direction in which they flew from their old location!
Even if birds were taken from their homes on the plane for hundreds of miles, when they were released, they flew to his home.
In another experiment, the scientist was taken from England duck eggs in Finland, and there hatched ducklings. And I must say that wild ducks living in England, lead a sedentary lifestyle, and ducks from Finland migrate in winter to the West of the Mediterranean sea.
The experiment showed an unexpected result. After the departure of the "Finnish" ducks on the South, went up into the sky and ducks hatched from "English" eggs. Ringed birds flew over the corresponding edges, which are usually crossed ducks from Finland, and reached the wintering grounds of their foster parents. Next year the majority of these ducks returned to Finland.
As the birds are guided in the way? We must recognize that while we do not fully know.
One of the hypotheses is that the birds feel the magnetic fields that surround the Earth. Magnetic lines are arranged in the direction from the magnetic North pole to the South pole. Perhaps these lines and serve as guides for birds.
The researchers performed the experiments: on the neck of the pigeon hung magnetic plate. This prevented the birds to navigate, but fully to lead them astray magnetic plates could not.
Additional guidelines for determining the direction of flight are features of the landscape (the bend in the river, mountains, groups of trees). It is possible that the birds are guided also by the location of the sun. On long flights the most important are, apparently, not terrestrial, and celestial cues: sun - day, moon and stars at night.
Most likely, birds in flight use all of these types of benchmarks: magnetic field, astronomical and landmarks.