Living on the Forest Edge: Flexible Habitat Use in Sedentary Pied Flycatchers Ficedula Hypoleuca during the Non-Breeding Season

Abstract

Seasonality affects the availability of resources within the African non-breeding environment of migratory songbirds. We are generally unaware of how songbirds respond to such seasonal dynamics, especially at small spatial scales that are relevant for individual birds. In this study we focus on the question of how migratory songbirds use small scale variation in seasonality in their non-breeding environment. Therefore, we measured individual movements of European Pied Flycatchers Ficedula hypoleuca in relation to habitat differences in foliation in a non-breeding site in Comoé National Park, Ivory Coast. Through a combination of remote sensing and radio tracking we show that flycatchers change their habitat use during the second half of the non-breeding season, where at the start of this period flycatchers occupy both savannah and forest, whereas with progressing foliation, after savannah burning and with the onset of the first rainfall, they narrow their site use in favour of savannah. Further measurements of arthropod abundance show that this behaviour is related to increasing numbers of particular arthropod groups during foliation, which indicates that flycatchers might track seasonal changes in food availability by moving between habitats on a small spatial scale. We hypothesize that individuals reduce their susceptibility to seasonality by establishing territories on the forest edge, where they can access both savannah and forest habitat, and thereby explore a wider variety of resources under different circumstances. In conclusion, these findings indicate that small-scale heterogeneity likely plays a key role in the ability of flycatchers to cope with seasonal dynamics on a local scale.