Every year more than 30,000 birds use theRia Formosa during their migrations and in winter, making this wetland among the three most important wetlands in Portugal. Some species are of European importance because of their important breeding populations, including the Little Tern, the Pied Avocet and Audouin’s Gull. The wide diversity of habitats here leads to the occurrence of a great number of species, one of the highest in Portugal, especially waterfowl, including waders and ducks in particular and, in lesser numbers, herons.The Ria Formosa is also noted for the highest numbers of wintering Eurasian Wigeon and breeding Red-crested Pochard in Portugal. On the land areas several species of woodland passerines occur, as well as various raptors.