b. Non-breeding coastal concentrations These include sites, usually in coastal areas, which hold feeding and moulting concentrations of waterbirds, such as divers, grebes and benthos feeding ducks.
c. Areas for pelagic species These sites comprise marine areas remote from land at which pelagic seabirds regularly gather in large numbers, whether to feed or for other purposes. These areas usually coincide with specific oceanographic features and their biological productivity is invariably high. They usually correspond to high productivity areas because they are related to several oceanographic variables (e.g. seamounts; Morato et al. 2008a, b) that increase the sea's productivity and available prey to a concentration of seabirds.
Island of Corvo
Cape Carvoeiro
d. Migration bottlenecks These sites are normally determined by topographic features, such as headlands and straits, so, due to their geographic characteristics, work like a bottleneck and influence the passage of whole populations of seabirds, or a large part of them, during their migrations. They are easily identifiable at some points of the European geography, such as the straits of Gibraltar, in Spain, and of the Bosporus in Turkey. In Portugal, data collected suggest that areas within this category might exist. Some examples are certain interisland canals in the Azores and Madeira archipelagos, the coast of continental Portugal (a compulsory route for many species of seabird during their migration) or Ponta de Sagres, in the extreme south-west of Mainland Portugal.
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Important Areas for Seabirds in Portugal