What type of hedgerows do Brown hairstreak (Thecla betulae L.) butterflies prefer? Implications for European agricultural landscape conservation THOMAS MERCKX 1 and KOEN BERWAERTS 2 1 Wildlife Conservation Research Unit, Recanati-Kaplan Centre, Department of Zoology, University of Oxford, Abingdon, UK and 2 Vlinderwerkgroep Natuurpunt vzw, Mechelen, Belgium Abstract. 1. Agricultural intensification is the main driver of global biodiversity loss. Agri-environment schemes (AES) are policy tools to counter this, but they need to be made more effective. 2. Here, we focus on the resource quality of hedgerows and woodland edges, which are widespread elements of most agricultural landscapes in Europe. We ana- lyse a set of structural factors and assess their relative importance for the Brown hairstreak butterfly. This species suffered severe declines because of agricultural intensification that may be indicative of changes for other widespread insect species that use hedgerows as resources. 3. Egg-deposition preferences were assessed by comparing egg densities among hostplant sections in two study landscapes. All sections were systematically searched during four consecutive years, resulting in 745 observed eggs. 4. We demonstrate that the ground plan outline and aspect of landscape elements, the relative position within landscape elements, and the amount of young hostplant growth are particularly relevant in explaining observed egg densities, and we link their importance with the butterfly’s behavioural biology. 5. Our study provides evidence that management focused on providing ample young growth, and transforming the landscape element ground plan outline from linear to a scalloped pattern, would benefit ectothermic species by providing more sheltered micro-climates when they use these structural resources for breeding, feed- ing and moving through typically exposed agricultural landscapes. We believe that integrating such management options within general AES would translate into effec- tive, large-scale conservation measures for Brown hairstreaks and other species alike. Key words. Agri-environment schemes, landscape ecology, landscape-scale conservation, micro-climate, Prunus spinosa, shelter. Introduction Agricultural land use intensification is the main driver of the severe loss of global biodiversity (Matson et al., 1997; Tilman et al., 2001; Tscharntke et al., 2005). Habitat loss, fragmenta- tion, eutrophication and landscape homogenisation are the often inter-related processes associated with intensified farming practices (Wilson et al., 1999; O ¨ ckinger et al., 2006). Not only do these processes negatively affect populations of rare, and typ- ically localised species, but even widespread habitat generalists are affected, resulting in often severe declines in abundance and distribution of once common species in a variety of taxonomic groups (Aebischer, 1991; Sotherton, 1998; Chamberlain et al. , 2000; Donald et al., 2001; Benton et al., 2002; Conrad et al. , 2006; Van Dyck et al. , 2009). As a result, agriculture and biodi- versity conservation have been traditionally viewed as incompat- ible, and ecologists and conservationists often focus on more or Correspondence: Dr Thomas Merckx, Wildlife Conservation Research Unit, Recanati-Kaplan Centre, Department of Zoology, University of Oxford, Tubney House, Abingdon Road, Tubney, OX13 5QL, UK. E-mail: thomas.merckx@zoo.ox.ac.uk Insect Conservation and Diversity (2010) doi: 10.1111/j.1752-4598.2010.00088.x Ó 2010 The Authors Journal compilation Ó 2010 The Royal Entomological Society 1