Mixed effects of landscape structure and farming practice on bird diversity

Bird abundance, species richness and diversity of bird communities were analysed on 59 plots during breeding season and 61 plots during winter (500 m × 500 m around winter wheat fields) in two contrasting regions of Germany differing in land-use history (West vs. East), landscape structural complexity (40–100% arable land) and farming practice (organic vs. conventional). Abundance, species richness and diversity were higher in West Germany, presumably due to the higher overall habitat-type diversity, and decreased with decreasing landscape complexity, this being marked for farmland and forest birds. In contrast, abundances of openland bird species were higher in East Germany during both seasons and increased with decreasing landscape complexity. During breeding season (but not in winter) organic farming enhanced the species richness of all bird groups, presumably due to more and diverse food resources. Farmland and forest bird species in agricultural landscapes therefore appear to be mainly enhanced by landscape complexity owing to the availability of nesting and sheltering places in non-crop habitats, while openland bird species require high proportions of arable land.

Research highlights
► During breeding season organic farming enhances bird abundance and species richness.
► In winter land-use history and landscape complexity influence bird occurrence.
► Farmland and forest birds increase with increasing landscape complexity.
► Openland birds decrease with increasing landscape complexity.