干旱区生态环境知识资源中心

Some 330 Nearctic bird species are known to migrate annually to the Neotropics, some as far as southern South America. Austral migrants tend to travel much shorter distances, often within South America, and many species engage in partial migrations. However, little is known of the routes or migration patterns followed by most of these birds. With the aim of better understanding migration patterns in northeastern Brazil, two sampling points were established in the Caatinga scrublands at Serra da Guia (Sergipe). Standardized monthly samples (3 days of mist-netting) were collected at each site between October 2008 and September 2009. A total of 98 species was captured, of which 24 were classified as partial or full migrants (including one Nearctic species, Vireo olivaceus). Thirteen of the 24 migrant species were flycatchers (Tyrannidae). Just over half of the 283 migrants captured belonged to two species, Elaenia chilensis and Turdus amaurochalinus. A peak in the number of species and individuals captured was recorded between March and July, coinciding with the Austral winter and peak precipitation/productivity in the study area. Brood patches were recorded in 11 species, only between March and September. In contrast to the general pattern of migrants, two flycatchers (Myiarchus tyrannulus and Myiophobus fasciatus) were captured only between November and February (non-breeding). Most other species were partial migrants or captured too infrequently to permit a reliable analysis of seasonal patterns. For these species, additional monitoring would be required to define migration patterns more clearly. Accepted 10 December 2010.