Distance to central-place drives species-specific habitat selection in sympatric insectivorous birds

Agricultural intensification is a major driver of land use change, thereby reducing biodiversity and leading to population declines across various animal groups. In response, animals can mediate some negative fitness impacts and navigate through agricultural landscapes with reduced resource availability by changing their habitat selection via movement decisions - particularly when constrained by central-place foraging, which requires balancing travel costs against energetic returns.

Here, using miniature ATLAS tags (Advanced Tracking and Localisation of Animals in real-life Systems), we tracked 101 house martins and 87 barn swallows at high-resolution to investigate their state-specific habitat selection and mapped the insect abundance and diversity across an intensively used agricultural landscape.

Both species mainly avoided arable fields and increasingly selected for forests and water bodies with distance from the colonies. House martins ranged farther from colonies than barn swallows and also showed strong distance-dependent selection for structurally complex habitats, such as extensive grasslands and green areas within villages. Furthermore, house martins selected for proximity to water bodies, while barn swallows' selection focused on proximity to woody vegetation structures. During our 2023 insect sampling window, habitat selection tracked mapped insect richness more closely than mapped insect abundance.

Distance-dependent divergence in space use suggests horizontal niche differentiation between sympatric central-place foragers, with potential implications for coexistence. Combined, our findings point to the importance of maintaining extensively used grasslands and small-scale habitat structures within intensively managed farmland to improve the abundance and diversity of prey for farmland passerines.