LOSING GROUND: BLACK GROUSE BROOD-REARING HABITAT PREFERENCES IN SHRINKING ALPINE MEADOWS INFORM TARGETED HABITAT RESTORATION

Alpine landscapes are increasingly affected by pastoral abandonment and shrub encroachment, threatening biodiversity and specialist species dependent on habitat mosaics. We investigated how female Black Grouse (Lyrurus tetrix) select brood-rearing habitat in the French Alps, where green alder (Alnus viridis) expansion is rapidly transforming semi-open landscapes into closed shrubland. We GPS-tracked 10 females across five breeding seasons (2017–2021), yielding 14 unique individual-years combination with high-resolution movement data. Using LiDAR-derived habitat maps (1 m² resolution) and integrated Step-Selection Analysis, we quantified habitat selection across multiple spatial scales and tested how reproductive status (brood-rearing vs. solitary) influenced fine-scale movement decisions. Habitat selection operated hierarchically. At the landscape scale, females established home ranges with 25–50% shrub cover—higher than expected from availability alone. Within home ranges, brood-rearing hens selected areas with balanced shrub-meadow proportions at a 900 m² scale, corresponding to relatively small alder patches. At the microsite scale, hens with and without brood used patch edges intensively, remaining in average respectively within 0 m and 4 m inside shrub boundaries while accessing adjacent open areas. Movement patterns reflected reproductive constraints: brood-rearing females exhibited shorter, more tortuous steps within shrub habitat compared to solitary hens, indicating deliberate persistence in covered areas. Our findings suggest a multiscale predation-foraging trade-off mediated by reproductive status. Brood-rearing hens prioritise shrub cover likely for chick protection while maintaining access to herbaceous foraging areas through edge-oriented movements. Conservation efforts should focus on maintaining structural heterogeneity with 30–50% shrub cover distributed as small patches embedded within meadows. This configuration optimises edge density and habitat complementarity, supporting Black Grouse persistence and broader typical alpine biodiversity under ongoing landscape change.