Unused railway lines as a contributor to bird abundance, species richness and diversity in intensively managed farmland

Agricultural landscapes are characterized by a variety of habitats resulting from man-made transformations of the natural environment. Progressing agricultural intensification is leading to a reduction in natural and semi-natural habitats, resulting in turn in a loss of biodiversity. In farmland, natural habitats such as field margins, hedgerows, and meadows are progressively declining or being transformed. There is a need for regionally adjusted schemes that balance agricultural production and biodiversity conservation due to strong differences even within one country. We present a potential tool that can mitigate biodiversity loss in farmland ecosystems. In this study, we compared transects on three different habitat types: unused railway lines, dirt road verges and fields in terms of overall, farmland and open land bird species abundance, richness and Shannon-Wiener diversity index as well as community composition in intensively managed agricultural landscapes. We predicted that 1) bird abundance, species richness and diversity would be greater in vegetation structure along unused railway lines due to their spontaneous vegetation character than in other habitats, and 2) bird community composition would be different between three habitat types (unused railway lines, farmland roads and transects in farming areas). Our findings demonstrated that habitats along unused railway lines provide a suitable environment for farmland birds, increasing bird diversity in the agricultural landscape and playing a wider role in biodiversity conservation. Vegetation structures along unused railway lines may act as alternative refuges for birds in each season, providing food resources, nesting, shelter, perching, singing, and resting sites as well as constitute a kind of ecological corridor running within an intensively used agricultural landscape.