Fragmented woodlands in agricultural landscapes: The influence of woodland character and landscape context on bats and their insect prey

Abstract

Agricultural expansion has led to the widespread destruction of habitats and the creation of fragmented landscapes. Woodland has been severely affected by habitat loss; remaining woodland is often highly fragmented and degraded, immersed in an agricultural matrix. Woodland is one of the most important habitats for bats because it offers roosting and feeding opportunities for many species. A number of agri-environment schemes aim to increase the amount and quality of woodland on agricultural land; however, little is known about how woodland character relates to bat abundance/activity and recommendations for woodland creation and management for foraging bats are scarce. We studied temperate bat communities and examined bat foraging activity and relative abundance (and insect prey availability) in 34 woodland fragments in agricultural landscapes using two complementary methods (acoustic monitoring and trapping assisted by an acoustic lure). We evaluated the relative importance of woodland vegetation character, patch configuration and surrounding landscape in order to assess the importance of local- vs. landscape-scale woodland management to bat populations. Bat abundance and activity were influenced by both local and landscape-level attributes. At the local scale, woodland vegetation character appeared more important than patch configuration. High activity levels of aerial hawkers (e.g. Pipistrellus species) were related to low tree densities and an open understory, while gleaning species (e.g. Myotis bats) showed the opposite trend. Areas of cluttered vegetation were associated with high insect (mostly Diptera) abundance and could act as sources of prey for certain bat species. Bats' responses to the surrounding landscape depended on species mobility. For relatively low mobility species (e.g. Pipistrellus pygmaeus), local woodland character was more important than the landscape context, whereas the opposite was observed for higher mobility species (e.g. Pipistrellus pipistrellus and Myotis bats). Higher bat activity levels were observed in small and isolated woodland fragments, and in sparsely wooded landscapes. This may reflect a more intensive use of woodland in landscapes where this habitat is scarce, where woodland creation should be prioritised. Woodland management and creation schemes should encourage habitat heterogeneity to fulfil the requirements of different bat species.