Position in the distributional range and sensitivity to forest fragmentation in birds: a case history from the Atlantic forest, Brazil

We tested the hypothesis that endemic bird species of the Brazilian Atlantic forest are more sensitive to forest fragmentation than non-endemics in a fragmented landscape in northern Parana state of southern Brazil. Levels of sensitivity (high, medium, and low) were previously determined in the landscape based on the occurrences of bird species in 14 forest fragments. We evaluated 112 forest bird species and found that endemic species were more sensitive than non-endemics. Among the endemic species, highly sensitive species tended to have smaller geographic ranges. In a second analysis, we determined that birds at the edges of their geographic ranges in northern Parana were more vulnerable to forest fragmentation. Combining both factors we found that endemic birds at the edge of their ranges were the most sensitive to fragmentation. Our results suggest that endemics and species at the edges of larger ranges might need larger tracts to ensure their continued existence within that region. Our results, however, also indicate that even small forest fragments may have considerable value for non-endemics and for species closer to the centres of their ranges.