Measuring difference in edge avoidance in grassland birds: the Corncrake is less sensitive to hedgerow proximity than passerines

Abstract

Edge avoidance is an important feature of habitat selection in grassland birds, as their density is usually reduced close to habitat boundaries. In many extensively managed European grasslands, fragmentation is caused by the presence of wooded hedgerows dividing meadows. Comparing the magnitude of hedgerow avoidance by co-occurring species is essential for the management of grassland areas and the implementation of efficient conservation schemes. We quantified hedgerow avoidance by the Corncrake and four grassland passerines in western France. As expected, all species avoided hedgerows, but the effect was less pronounced for the Corncrake. We hypothesize that this may reflect a lower predation risk towards the larger and most inconspicuous species. Alternatively, social communication in Corncrakes may be less impeded by wooded vegetation than in passerines. However, the mechanisms responsible for the observed pattern remain uncertain. Nevertheless, our study provides a general technique that can be applied to measure boundary avoidance. This information is important for policymakers in their efforts to improve management guidelines, which often do not take edge effects into account.