Distribution of shorebirds in north-eastern Brazil: preferences between open beaches and inner estuarine habitats

We investigated the distribution of migratory shorebirds (Charadriidae and Scolopacidae) in three estuarine complexes along the coast of Paraíba, Brazil. We sought to answer the following questions: (1)  Do species densities differ among habitats? (2) What factors (estuary, month, habitat type, and estuary  size) have the greatest influence on variation in densities? (3) How similar are the survey sites, based on  their species-composition and the structure of their assemblages of birds? We conducted 72 surveys between Sep 2010 and Apr 2011, recording 13 species of migratory shorebird. Type of habitat had the greatest influence upon variation in density. The species composition of open beaches was clearly  different from that of inner estuarine habitats. Our findings suggest that estimates of shorebird numbers in estuarine complexes should include at least two strata, open beaches and inner habitats, to minimize the likelihood of failing to detect species with restricted distributions.