Response of farmland birds to oilseed rape areas

Oilseed rape is one of the major crops used in Europe for biofuel production. It has several characteristics (dense crop structure, production of various food resources for birds, including insects) that could impact the farmland birds positively or negatively depending on the species. The consequences of the increase of oilseed rape areas on bird populations and communities, however, are poorly understood. Indeed, studies focusing on the impact of oilseed rape remain essentially monospecific and regional. Our work aims to answer several questions: Is there a response of farmland bird populations to oilseed rape? Is this response uniform or does it depend on the context including other agricultural and landscape features? Are species supposed to be well adapted to oilseed rape (insectivorous diet, low branches feeding layer) those actually favored? The theoretical framework of this study is landscape ecology and species distribution models. We used data from the French breeding bird survey from 2006 to 2010, and sought to characterize the response of farmland bird abundance to oilseed rape on 4 km ² agricultural patches spread over the mid-north of France. Statistical models took a wide range of landscape variables available in national databases with high spatial resolution into account: crops and grass, hedgerows and wooded elements, non-agricultural areas, road network. Analyzes were conducted species by species on two types of contrasting landscapes, cash crops and mixed farming. Geographic variability of responses was determined on local sub-datasets. The results suggest that responses may depend on the agricultural context, and that the most impacted species are not those expected.