Avian species-area relationships indicate that towns are not different from natural areas

Urban areas host many bird species, and urban species richness can be compared with that in natural areas using species-area relationships (SARs). We used a multimodel selection approach to investigate the influence of area, human population, elevation and climatic variables on species richness of breeding birds from 34 towns and 54 nature reserves in Italy. Using the linearized power function, area was identified as the most important correlate of avian species richness in both urban and natural areas. The SARs did not differ significantly between towns and reserves, although human density had a negative effect on bird richness. These findings underline the possible importance of urban areas in biodiversity conservation, but also stress that human density is a factor reducing species richness. However, species richness alone cannot inform conservation priorities because it does not take into account the different conservation values of species.