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

<p>Capsule Vegetation structure and invertebrate abundance interact to influence both foraging sites andnestling provisioning rate; when invertebrate availability is low, adults may take greater risks to providefood for their young.Aims To investigate nesting and foraging ecology in a declining farmland bird whose fledging successis influenced by the availability of invertebrate prey suitable for feeding to offspring, and where perceivedpredation risk during foraging can be mediated by vegetation structure.Methods Provisioning rates of adult Yellowhammers feeding nestlings were measured at nests on arablefarmland. Foraging sites were compared with control sites of both the same and different microhabitats;provisioning rate was related to habitat features of foraging-sites.Results Foraging sites had low vegetation density, probably enhancing detection of predators, or highinvertebrate abundance at high vegetation density. Parental provisioning rate decreased with increasingvegetation cover at foraging sites with high invertebrate abundance; conversely, where invertebrateabundance was low, provisioning rate increased with increasing vegetation cover.Conclusions Vegetation structure at foraging sites suggests that a trade-off between predator detectionand prey availability influences foraging site selection in Yellowhammers. Associations between parentalprovisioning rate and vegetation variables suggest that where invertebrate abundance is high birdsincrease time spent scanning for predators at higher vegetation densities; however, when prey are scarce,adults may take more risks to provide food for their young.</p>