Population restoration of the nocturnal bird Athene noctua in Western Europe: an example of evidence based species conservation

Agricultural intensification is one of the key factors leading to the recent global biodiversity crisis. Especially farmland species are negatively affected by both, agricultural intensification and abandonment. The nocturnal Little Owl Athene noctua inhabits low-intensity agricultural landscapes and showed severe population declines over Central Europe during the past decades. In this study we analysed the effects of land-use changes on the Little Owl between 2001 and 2010 across Western Luxembourg. We assessed the occurrence of A. noctua and tested for the speciesA ' habitat use and the effects of nesting boxes. In total we analysed 63 occupied and unoccupied study sites over a 20 km x 40 km study region located in Western Luxembourg. Our data indicate a transformation of pastures with single trees into arable land during the past 10 years. As a response to a perceived decline of the species in the region a total of 450 nesting boxes were installed in high stem orchards which are considered potentially suitable habitats, in areas with and without past A. noctua occurrence. We tested how nesting boxes and various habitat structures in the surrounding (e.g. percentage of high stem orchards, habitat heterogeneity) affected the occurrence of A. noctua. Despite agricultural intensification, the presence of A. noctua increased, most likely as a result of the installation of nesting boxes. We found that land-use parameters such as arable land, forests, pastures and pastures with trees had a negligible impact on the occurrence of A. noctua. Our findings suggest that the conservation of the little owl can be supported with comparatively simple and convenient measures, such as the installation of nesting boxes, even in an intensively used environment, provided that sufficient prey is available.