Effects of landscape, land use and vegetation on bird community composition and diversity in Inner Anatolian steppes

Abstract

We present here the first systematic study on drivers of bird community composition and diversity in Anatolian steppes (Turkey), an environment important for populations of threatened grassland birds yet underrepresented in conservation networks. We focused on one million hectares of mountainous land with a long and varied land use history, and collected quantitative data on breeding birds as well as environmental, vegetation, landscape and land use parameters at 32 sites. Data were analyzed by canonical correspondence analysis (CCA) and hierarchical partitioning to understand avian community structure and reveal major drivers of observed patterns. Bird communities in high-altitude steppes of inner Turkey showed patterns in species richness and community composition that were best explained by an altitudinal gradient and by human activities. Steppe birds occurred most often in cropland abandoned 20–50 years ago with good coverage of erect leafy plants while overall avian diversity tended to increase with reduced grazing pressure and with nearby presence of rural settlements. CCA results revealed a contrast between highly heterogeneous anthropogenic environments in warmer and drier land with woody elements, and treeless steppes at higher elevations that were, apart from transhumant grazing, little influenced by human activities. The former sites were characterized by the occurrence of several grassland birds along with a variety of generalist species, some of which required the presence of trees, while the latter sites were less diverse but usually with a higher proportion of steppe-dependent birds in their composition. To conserve steppes for birds, we recommend as key actions to maintain the current landscape mosaic, sustain low to moderate grazing levels and use our findings in developing a network of protected areas.