ROLE OF BUILDINGS AS NEST-SITES IN THE RANGE EXPANSION AND CONSERVATION OF CHOUGHS PYRRHOCORAX-PYRRHOCORAX IN SPAIN

The chough Pyrrhocorax pyrrhocorax is at present a rare species in the Palearctic region, probably due to to recent changes in traditional a gro-pastoral systems. Naturally a cliff-nesting species, it has, howev er, recently occupied new areas with suitable feeding habitats using o ld buildings as nesting sites. Nest-site availability, breeding densit y, nest spacing and population numbers of choughs were compared in thr ee widely spaced Spanish areas (totalling 1213 km(2)). In Madrid, nest availability is limited to cliffs, leading to higher breeding density and nest aggregation than in Los Monegros and Campo Azalvaro, where c houghs use buildings. These artefacts maintain large populations (we e stimated 1175 breeding pairs in 9716 km(2)) that are expanding, increa sing the species' range and linking up with the original and isolated montane nuclei. Human disturbance, persecution and the near disappeara nce of old buildings are the main threats for these new populations. C opyright (C) 1996 Esevier Science Limited