Due to its geographical position and climatic conditions, Denmark is situated on one of the main migratory routes. They thus pass over Denmark twice a year on their way to and from their winter quarters in western Europe, the Mediterranean countries and Africa. Migratory routes over Denmark are generally spread over a wide front, but in certain cases migration is concentrated, due to special geographical conditions. Most land birds prefer to migrate over land as much as possible, and coasts therefore form guidelines for their route. Not until the east and west coasts of Jutland meet at Skagen do the birds pluck up courage and fly over the Kattegat to Swedish coast 60 km away.
Many seabirds also prefer to use the coasts as guidelines during migration.
These birds can also be seen at Skagen in large numbers in spring, for example cormorants, divers, many species of ducks and waders, auks, gulls and terns. In autumn, the prominent position of the spit of land between the two seas at Skagen offers special conditions for the occurrence of seabirds. There are very few other locations in Denmark where seabirds can be seen in such large numbers and in such great variety. The birds are attracted by large quantities of fish and fish fry which can be found in the waters near the coast. The chief species of seabirds to be seen are divers, cormorants, shearwaters, fulmars, gannets, skuas, gulls, terns and auks.