The western osprey (Pandion haliaetus) is a fish-eating bird of prey with a cosmopolitan range. After been practically extinct, they have returned to several locations in Holland such as the Biesbosch and Oostvaarderplassen. After their
annual migration to Africa, they return in springtime with great precision to their nest, after a flight of almost 6000 km. Most migratory birds such as geese, godwits, and swifts, learn their flying routes from their parents or other
migratory birds following the same routes. Birds like the osprey however migrate alone and rely on a complex -probably innate- system of navigation using the earth's magnetic field, using magnetite mineral sensors buried in their skulls. Other
birds like the buntings may use the starry sky, and shearwaters seem to use their smell, allowing them to smell the coastline when flying over the sea. Day flyers like pigeons use the sunlight and position of the sun.
These factors may also interact with one another, like sunlight and the earth's magnetic field both affecting navigation.
Source: NRC Weekend. Nienke Beinntema April 4 2021