Habitat, Climate, Topography and Management Differently Affect Occurrence in Declining Avian Species: Implications for Conservation in Changing Environments

Climate and land-use change are the most severe threats to biodiversity; their effects are often intermingled, also with those of landscape/habitat management. Birds of mountain grassland are declining throughout Europe. Disentangling climate effects from those of land-cover and management on their occurrence is essential to identify distribution drivers, potential impacts of climate/land-use changes, and effective conservation strategies. We investigated the occurrence of water pipit (elevation specialist), skylark and red-backed shrike (elevation generalists) in Central Apennines, Italy (750-2130 m asl), using point counts. Topographic/climatic, land-cover and management fine-scale variables were considered as potential occurrence predictors in Generalized Linear Models. For all species, combining different types of predictors led to the most accurate models, but the relative importance of single-groups varied: land cover was the most important for skylark, climate/topography for water pipit, all three groups had similar support for red-backed shrike. Skylark was positively affected by solar radiation and grassland cover, and negatively by bare ground, hedgerows, rocks, shrubland, ski-pistes and buildings, confirming sensitivity to anthropic alteration of semi-natural grassland. Water pipit was favoured by grazing and negatively impacted by shrubland and average temperature (most important predictor). Red-backed shrike was affected negatively by broadleaved forest and grazing occurrence, quadratically by isolated shrubs and positively by grassland cover. Climate was a fundamental determinant of water pipit occurrence, but not for the other species. Land-cover was important for all species and also management factors were invariably included in models. Climate, habitat and management factors differently contributed to occurrence patterns in these declining species. Conservation strategies need to embrace landscape planning to preserve grassland extents/mosaics, identify climate refugia for water pipit and implement dedicated management (preventing new ski-pistes over areas suitable for birds and carefully planning grazing). It should be feasible to combine local, sustainable economies with biodiversity conservation into landscape planning for Central Apennines.