International importance and drivers of change of upland bird populations
The UK holds an internationally important assemblage of upland birds, comprising a unique mix of oceanic, boreal and northern species, with many at the edge of their breeding ranges and some with exceptional breeding densities (Thompson et al., 1995). As well as the intrinsic conservation value of this assemblage, its role in contributing to the tourism potential and the economy of such areas is increasingly recognised, whilst further economic benefits arise from the sport shooting of red grouse Lagopus lagopus scoticus (Price et al., 2005; Sotherton et al., this volume). Thus, upland birds provide a valued cultural and recreational ecosystem service. The assemblage includes top-level predators, as well as a wide range of invertebrate feeders and a few species that are largely herbivorous. The maintenance of viable upland bird populations from across a range of trophic levels may therefore provide a useful indicator of environmental change in upland areas at a range of scales, from local management-driven alteration to large-scale climatic changes.