Aspects of seabird biology at Atol das Rocas Biological Reserve, Rio Grande do Norte, Brazil

Abstract

Reserva Biológica do Atol das Rocas is a marine biological reserve located about 250 Km west of Natal - Rio Grande do Norte, Brazil. It has an abundant fauna of visiting or nestíng seabirds. Its 2 islets, around 3 ha each, shelter the largest breeding colonies of Masked Booby Sula dactylatra and Brown Noddy Anous stolidus in Brazil and of Sooty Tern Sterna fuscata for the South Atlantic. Data on biological aspects of the bird species were collected in 1991, 1993 and 1994. Field work included population censuses; mapping of nesting areas, nest building; eggs, chicks and adults biometry and characterization; bird banding and recoveries, and general observations. The results indicate a breeding period seasonality, possible Iinked with climate. Climate also influences the local vegetation. The drier part of the year expanded the nesting habitat of Sterna fuscata and Anous stolidus (namely at Cemitério islet). The abundance and occurrence of fish species (preys) that are important on seabirds' diet, may also influence  the nesting period. Recoveries of banded birds shows some Sula leucogaster individuals that are born in other parts of the Brazilian coast and come to Rocas Atoll to settle. It also indicates that Sula sula and Anous minutus coming from Fernando de NoronhaIs. use there, serve to forage.