An agri-environmental scheme enhances butterfly dispersal in European agricultural landscapes

The loss of connectivity caused by habitat fragmentation is one of the greatest threats to biodiversity. This is of particular concern in agricultural landscapes, which combine increased levels of fragmentation with larger numbers of endangered species than other landscapes. Corridors (e.g. linear landscape elements) are a popular conservation strategy to counteract fragmentation effects. Grassy field margins (GFMs) have been established throughout Europe as part of agri-environmental schemes. The primary goal of these measures is to protect water quality, but it is suggested biodiversity may benefit via a corridor function. Being set up along watercourses, GFMs may spontaneously form a coherent network of corridors in agricultural landscapes. We tested this hypothesis by monitoring movement strategies of Meadow brown butterflies (Maniola jurtina L.) in GFMs. Results indicated that butterfly movement was facilitated by this new landscape element, supporting its corridor function. Mechanistically, dispersal occurred through foraging movements rather than movements adapted to dispersal. Spatial configurations of GFMs were also explored in a large agricultural area and demonstrated that the GFM policy is adequate to provide a corridor function.

• Grassy field margins promote dispersal by facilitating and directing butterfly movement. • Dispersal is more likely to occur via corridor than via agricultural matrix. • The spatial configuration of GFMs in the landscape is adequate to the corridor function.