Influence of management practices on nest site habitat selection, breeding and diet of the common buzzard Buteo buteo in two different areas of Spain

Aims: The density, nest spacing, breeding habitat selection, diet and productivity of two sedentary populations of common buzzards was studied for six to eight years in two different areas of Spain, in relation to landscape and anthropogenic factors. Location: Bizkaia (Northern Spain) and Murcia (Southern Spain) Methods: Two populations of common buzzard were studied, one from 1996-2003 in Bizkaia (Northern Spain, Eurosiberian region) and the other one from 1998-2003 in Murcia (Southeastern Spain, semiarid Mediterranean region). Breeding parameters and diet were obtained every year. Home range habitat preferences were examined by comparing habitat composition around 18 occupied sites and 17 non-occupied sites in both areas, using logistic regression and two-sample tests. Results: The density was 45 territories per 100 km ² in Bizkaia and 8 territories per 100 km ² in Murcia. Productivity was similar in both areas at 1.72 and 2 fledged young per successful pair respectively. Diet was dominated by small-sized prey in Bizkaia and medium-sized prey in Murcia. More intensive timber management in Bizkaia caused buzzards to select mature pine forest, independently of the size of the forest patch. In contrast, timber management practices in Murcia result in continuous pine forests, where Common buzzards selected mature patches far from the forest edge. Moreover, buzzards appear to avoid sources of human disturbance in both areas. Conclusions: Differences in habitat structure between the regions appear to drive differences in density. Moreover, prey diversity differed between regions probably partly as a response to timber management and this probably contributes to the observed differences in population structure. Common buzzards appear to respond to habitat alteration in a variety of ways, ranging from their choice of forest structural characteristics to the placement of the nest site.