Changes in butterfly movements along a gradient of land use in farmlands of Transylvania (Romania)

Context Agricultural transformation and increased land use intensity often lead to simplified landscapes and biodiversity loss. For animals, one possible mechanism underpinning biodiversity loss in agricultural landscapes is the disruption of movements. The disruption of movements may explain, for example, why butterfly communities in agricultural landscapes are often dominated by generalist species with high mobility. Objectives Here, we investigated how the movement patterns of butterflies characterised by different levels of mobility changed along a gradient of agricultural land use intensity. Methods To this end, we studied 15 landscapes in low-intensity farmland in Central Romania, measuring 10 ha each and covering a gradient of landscape heterogeneity and woody vegetation cover. In these landscapes, we tracked movements of 563 individuals of nine butterfly species. Results Our findings showed that overall movement activities differed significantly between species, corresponding well with expert-derived estimates of species-specific mobility. Interestingly, species of low and high mobility responded in opposite ways to increasing levels of landscape heterogeneity. In relatively simple landscapes, the movement patterns of low and high mobility species were similar. By contrast, in complex landscapes, the flight paths of low-mobility species became shorter and more erratic, whereas the flight paths of high-mobility species became longer and straighter. An analysis of the land covers traversed showed that most species avoided arable land but favoured the more heterogeneous parts of a given landscape. Conclusions In combination, our results suggest that non-arable patches in agricultural landscapes are important for butterfly movements, especially for low-mobility species