The film was shot on location in northeastern Bulgaria between the Black Sea and the Danube - a district that is crossed by a route that has been used by migrant birds for centuries. The camera has captured many rare species, which spend the winter in the South and come back in spring: cranes, pelicans, white and black storks, white egrets and many others. In hospitable waters of the coast lakes, which do not freeze even in winter, swans, wild ducks and sea gulls also winter.