Space-time patterns and drivers of migrant bird communities in coastal Piaui State, Brazil/Patrones y factores espacio-temporales de comunidades de aves migratorias en el estado costero de Piaui, Brasil

Introduction: Migration is a natural phenomenon that includes annual movements of many bird species in response to seasonal cycles. With approximately one third of all living bird species, South America has an important avifauna, and many migrants land in Brazil at stopping points and wintering sites. Objective: To identify associations between migrant birds and coastal vegetation, and environmental influence of on migration. Methods: At 10 points along the coast of Piaui State, Brazil, we made visual censuses and mist net captures, between April 2009 and February 2016. Results: We identified 82 migrant bird species (13 orders; 28 families) that represented 41 intracontinental migrating species, 26 northern visiting species, 14 nomad species and one vagrant species. The richness peaks were at the beginning and end of both dry and rainy seasons, matching insolation and atmospheric pressure. There were spatial pattern differences among vegetation complexes. Chrysolampis mosquitus is an indicator of caatinga vegetation, Numenius phaeopus of wetland, Charadrius collaris of non-flooding fields, Rostrhamus sociabilis of forest-grassland transition, and Columbina picui of orchards. Despite differences in number and species composition within vegetation types, the temporal pattern in species richness was similar among flooded fields, non-flooded fields, and transition grassland categories. Conclusions: Migrant birds occupy specific environments during their permanence along the coast of Piaui State, with richness matching insolation and atmospheric pressure. Key words: climatic variables; environment; movements; migration chronology; stopover. Introduccion: La migracion es un fenomeno natural que incluye los movimientos anuales de muchas especies de aves en respuesta a los ciclos estacionales. Con aproximadamente un tercio de todas las especies de aves conocidas, America del Sur tiene una avifauna importante y muchas aves migratorias tienen puntos de parada e invernada en Brasil. Objetivo: Identificar asociaciones entre las aves migratorias y la vegetacion costera, y la influencia del medio ambiente en la migracion. Metodos: En 10 puntos a lo largo de la costa del Estado de Piaui, Brasil, realizamos censos visuales y capturas con redes de niebla, entre abril 2009 y febrero 2016. Resultados: Identificamos 82 especies de aves migratorias (13 ordenes; 28 familias) que representaron 41 especies migratorias intracontinentales, 26 especies visitantes del norte, 14 espec