Breeding prerequisites for Ortolan Bunting Emberiza hortulana in Swedish farmland with special focus on foraging

Abstract

Ortolan Buntings Emberiza hortulana are rapidly decreasing in Sweden. Changes in agricultural practices are the main reason. Landscape simplification due to the removal of semi-natural elements leads to a lack of breeding habitats. Furthermore, due to intensive artificial fertiliser applications and advanced agricultural equipment and technology, crops grow both taller and denser than 50 years ago. In Kvismaren, south central Sweden, Ortolan Buntings have been studied since 2009. Here, we focus on one question: what defines a good foraging microhabitat? In 2017, nesting areas for five females and four males were identified and we did 271 feeding observations. Average foraging distance at different nests varied between 47 and 114 meters. About 70% of the foraging activities took place within crop fields. Ortolans utilized mainly unsown rows, later to be used by tractors for spraying etc. and patchy parts of standing crops. Invertebrates extracted from those areas looked dark, suggestive of ground-dwelling species. Our key management recommendation to create better microhabitats for feeding can be easily achieved by most farmers: to leave two unsown sowing rows (amounting to 0.38 m in width) for each tractor wheel to follow.