Choughs Pyrrhocorax pyrrhocorax breeding in Wales select foraging habitat at different spatial scales

Abstract

Capsule: At coarse spatial resolution breeding Choughs showed strongest selection for grazed habitats, while at a finer resolution they selected areas with shorter swards and more friable soils. Aims: To explain habitat preferences of foraging Choughs during breeding using the physical characteristics of the habitats at three spatial resolutions: between broad habitat and management types, between compartments within types, and within individual compartments. Methods: The use of 15 different habitat and management types by 14 pairs of Choughs at four coastal breeding sites was measured and selection coefficients obtained. Vegetation and soil characteristics were used to explain variation in these coefficients at a coarse spatial resolution. Similar data in 'selected' and 'avoided' parts of individual compartments were used to explain preferences at a finer resolution. Results: Grazed habitats were most heavily used, although paths and stone-faced earth banks were most strongly selected. Sward height explained most variation in selection coefficients at a coarse spatial resolution, with the shortest swards used most. Within compartments, 'selected' foraging sites had shorter swards and soil that was easier to probe. Comparisons between years suggested large-scale preferences were the same, but changes in physical characteristics did not explain changes in the use of individual compartments. Conclusion: These and previous results suggest consistency in habitat selection at a coarse spatial resolution. The use of grazing to maintain or increase the area of sward approaching 2 cm in height is recommended to ensure that where prey size and density are profitable, some are always accessible. © 2005 British Trust for Ornithology.