Effects of Anticoagulant Rodenticides and Farm Habitat Structure on Avian Communities in Livestock Farms

Rat control using anticoagulant rodenticides on livestock farms is a widely applied practice worldwide. Birds can be exposed to rodenticides through direct ingestion or secondary poisoning, resulting in mortality or sublethal health effects. While impacts on raptors and owls are well documented, potential effects on songbird communities in farmland settings have received limited empirical investigation. To address this gap, avifaunal surveys were conducted on 12 livestock farms in the Münsterland, Germany, during 2021–2022, comparing farms with and without rodenticide application to assess impacts on songbird and farmland bird communities. In addition, farm structures, such as the proportions of grassed areas and buildings, were quantified using spatial analysis (linear mixed-effects model). Farm structure showed patterns in bird abundance and community composition, with the proportion of buildings and grassed area showing the most notable associations with bird abundance and ground-nesting species respectively. Rodenticide application showed possible associations with the number of individual birds. However, none of those patterns reached statistical significance, and causal mechanisms remain unclear due to the observational design. Larger-scale studies are needed to assess population-level consequences and optimize rodenticide use alongside habitat management.