Why do birds migrate to the south in autumn?

Many birds such as starlings, cranes and swallows migrate to the south in autumn because they do not find enough food in winter. It is not good to feed the birds because it may disturb their regular habits of finding food for themselves. Their destination and the migratory path is the same every year. For years, scientists puzzled over the birds’ ability to take exactly the same path every year but now it is assumed that birds possess a ‘magnetic sense of direction’ and orient themselves to the magnetic field of the Earth, using the position of the sun during the day, and the stars at night.