Spatial and temporal differences in the abundance of black grouse and other moorland birds in relation to reductions in sheep grazing.
The effect of agri-environment schemes introduced to promote heather regeneration in moorland habitats on breeding birds was assessed at 12 pairs of sites in northern England. Sheep reductions were associated with increases in 'heath' species and cotton grass Eriophorum spp., but less heath rush Juncus squarrosus. Plots with reduced sheep supported 59% fewer breeding waders, particularly lapwing V. vanellus, and 60% fewer grey partridge Perdix perdix. Sheep reduction probably benefited black grouse Tetrao tetrix, which showed an increase in lekking males of 4.6% (SE = 2.1) per annum following stock reduction compared to a decline of 1.7% (SE = 1.4) per annum on plots without stock reduction. Sheep removal in autumn and winter was associated with the presence of large (up to 40) flocks of black grouse. Sheep reduction had conservation benefits, at least for black grouse, but may negatively affect overall avian biodiversity if implemented on large spatial scales. Development of appropriate scales of habitat mosaics is essential for optimising bird conservation in the uplands.