The importance of the Azores as a place of excellence for the occurrence of migratory species or nesting birds is unquestionable. It is still the best European spot for the observation of migratory birds in the Americas, with special emphasis on Corvo Island. In addition to the rare and endemic species that make birdwatchers delight - the Priolo and the Paínho-de-Monteiro - there are resident birds such as the Canary of the Land, the Chaffinch, the Estrelinha, the Woodpecker and the Goshawk. The Azores also guard the world's most important nesting populations of Cory's and Garajau-Rosado, marine species extremely sensitive to the pollution of their habitat. Birdwatching is assured in all three groups of the archipelago, with companies providing services on almost every island.