The Wadden Sea is famous for its rich flora and fauna, especially birds. Hundreds of thousands of waders, ducks, and geese use the area as a migration stopover or wintering site. It is also a rich habitat for gulls and terns, as well as a few species of herons, Eurasian spoonbills and birds-of-prey, including a small and increasing breeding population of white-tailed eagles. However, the biodiversity of Wadden Sea is smaller today than it once was; for birds, greater flamingos and Dalmatian pelicans used to be common as well, at least during the Holocene climatic optimum when the climate was warmer. Some regionally extinct species are still found here.