Habitat correlates of Red-legged partridge (Alectoris rufa) breeding density on Mediterranean farmland

Red-legged Partridges (Alectoris rufa) are highly prized declining gamebird s of the western Palearctic, for which there is a shortage of habitat use i nformation on Mediterranean farmland. Habitat correlates of Red-legged Part ridge breeding density were assessed on an area of mixed farmland, in south ern Portugal. Partridge pairs were censused during spring 1992-94 by territ ory mapping. Partridge locations, land use, dirt tracks and water lines wer e mapped and incorporated into a vector-based Geographic Information System . Contours of partridge density were established for each spring through ke rnel smoothing and superimposed onto the remaining layers of information, t o give the proportions of each land use, density of tracks, density of wate r lines, density of field boundaries, landscape diversity and density of br eeding pairs within each contour region. Simple and multivariate linear reg ression were used to relate partridge density to the independent variables. Density of tracks, proportion of abandoned rice fields and of unharvested olive-tree groves were positively correlated with partridge density, which agrees with the reported tendency of partridges to select fixed features wi th uncultivated tracts within the arable landscape. Recent fallows were als o associated with high partridge densities but old ones were associated wit h low densities. Grasslands were negatively associated with partridge densi ty, probably owing to low vegetation and disturbance by domestic stock. Man agement practices that could favour higher breeding densities on less used habitats are suggested.