Relative effects of fragment size and connectivity on bird community in the Atlantic Rain Forest: Implications for conservation

Abstract It is known that large fragmentsizes and high connectivity levels are key components for maintaining species in fragments; however, their relative effects are poorly understood, especially in tropical areas. In order to test these effects, we built models for explaining understorybirds occurrence in a fragmentedAtlantic Rain Forest landscape with intermediate habitat cover (3%). Data from over 9000 mist-nethours from 17 fragmentsdiffering in size (2–175 ha) and connectivity (considering corridor linkages and distance to nearby fragments) were ranked under a model selection approach. A total 1293 individuals of 62 species were recorded. Species richness, abundance and compositional variation were mainly affected by connectivity indices that consider the capacity of species to use corridors and/or to cross short distances up to 30 m through the matrix. Bird functional groups were differently affected by area and connectivity: while terrestrial insectivores, omnivoresand frugivoreswere affected by both area and connectivity, the other groups ( understory insectivores, nectarivores, and others) were affected only by connectivity. In the studied landscape, well connected fragmentscan sustain an elevated number of species and individuals. Connectivity gives the opportunity for individuals to use multiple fragments, reducing the influence of fragmentsize. While preserving large fragmentsis a conservation target worldwide and should continue to be, our results indicated that connectivity between fragmentscan enhance the area functionally connected and is beneficial to all functional groups and therefore should be a conservation priority.