Occurrence of the Eastern Slaty Thrush (Turdidae) in southern Brazil during the non-breeding season

Abstract

There are many gaps in the knowledge about neotropical bird migration patterns. Among these gaps is the permanence of some non-migrating individuals at their breeding sites, outside their wintering grounds. There is evidence that Turdus subalaris can occur in southern Brazil during the non-reproductive period. The objective of this work was: (a) to verify possible occurrences of T. subalaris in southern Brazil during its non-breeding season and; (b) to relate these occurrences to years of harsh winters (caused in southern Brazil mainly by the influence of the climatic phenomenon La Niña). After synthesizing specific literature data and ornithological collection records, the occurrence data were compared with the climatic events of the preceding years. Thirteen T. subalaris individuals were recorded in southern Brazil during the breeding season between 1973 and 2013. Eight of these records (61.53%) occurred in years preceded by harsh winters. These new data indicate that its migration dynamics are more complex than previously thought, indicating that forest formations in southern Brazil may act as habitats for this species during the post-reproductive resting period.