Nest and foraging‐site selection in Yellowhammers Emberiza citrinella: implications for chick provisioning

摘要

Capsule Vegetation structure and invertebrate abundance interact to influence both foraging sites and\udnestling provisioning rate; when invertebrate availability is low, adults may take greater risks to provide\udfood for their young.\udAims To investigate nesting and foraging ecology in a declining farmland bird whose fledging success\udis influenced by the availability of invertebrate prey suitable for feeding to offspring, and where perceived\udpredation risk during foraging can be mediated by vegetation structure.\udMethods Provisioning rates of adult Yellowhammers feeding nestlings were measured at nests on arable\udfarmland. Foraging sites were compared with control sites of both the same and different microhabitats;\udprovisioning rate was related to habitat features of foraging-sites.\udResults Foraging sites had low vegetation density, probably enhancing detection of predators, or high\udinvertebrate abundance at high vegetation density. Parental provisioning rate decreased with increasing\udvegetation cover at foraging sites with high invertebrate abundance; conversely, where invertebrate\udabundance was low, provisioning rate increased with increasing vegetation cover.\udConclusions Vegetation structure at foraging sites suggests that a trade-off between predator detection\udand prey availability influences foraging site selection in Yellowhammers. Associations between parental\udprovisioning rate and vegetation variables suggest that where invertebrate abundance is high birds\udincrease time spent scanning for predators at higher vegetation densities; however, when prey are scarce,\udadults may take more risks to provide food for their young.