Bird composition changes in urban reserves in Buenos Aires Metropolitan Area: unraveling patterns and processes using eBird data

Urban reserves are important for education, scientific research and biodiversity conservation. Citizen-science initiatives, such as eBird, may provide important information. The aim of this study was to compare avian composition changes using the eBird data-set across four urban reserves in the Buenos Aires Metropolitan Area (AMBA) located in a biological corridor on the coast of the Río de la Plata: Reserva Ecológica Costanera Sur (CS), Reserva Ecológica Costanera Norte (CN), Reserva Ecológica Vicente López (VL) and Parque Natural Municipal Ribera Norte (RN). We randomly selected 100 avian lists for each reserve, loaded in eBird between August 2014 and February 2017 and calculated total dissimilarity, and their additive components of nestedness and species turnover using the Jaccard index with presence-absence data. The average total dissimilarity between reserves was 32% (SD= 4%). The highest values of dissimilarity were between CS and the rest of reserves, probably because it is bigger and has the highest species richness. Between VL, RN and the other reserves the dissimilarity was due to turnover, because they have more than 20 species absent in CN and CS. Between CS and CN, nestedness was the principal component of dissimilarity; this means that the bird community of CN is a subset of the CS community. Despite of its proximity and environmental similarities, the differences in bird composition allow the riparian biological corridor to have 80% of total bird species in Buenos Aires Province. We highlight the usefulness of eBird data to understand patterns and processes of bird communities in urban green areas.