Bird migration is closely related to climatology and meteorology, as they determine food availability in the different seasons.
The birds that breed in northern Europe set off on a journey in autumn. They make their way in stages to the mild and warm areas of European and Africa, which are their winter-feeding grounds.
At the end of the winter, the days get longer and heralds the start of spring. The birds then start to make their way north. Thousands of birds use the short, but fruitful northern European summers to feed off the abundance of insects, fruit and prey at that time of year.