Density, nest sites, diet, and productivity of Common Buzzards (Buteo buteo) in the Italian pre-Alps

We studied a Common Buzzard (Buteo buteo) population of 32-35 territorial pairs between 1993 and 1999 in a 113-km2 plot located in the central Italian pre-Alps. Density progressively increased from 28 to 31 pairs/100 km2. Territorial pairs were regularly dispersed with a mean distance from the nearest occupied nest of 1108 m (N = 108). Eighty-one percent of 108 used nest sites were on cliffs, while the remaining 19% were placed on mature trees. Each year, 16-21% of the nests built by Common Buzzards were taken over by migratory Black Kites (Milvus migrans). Mean laying date was 9 April (earliest = 7 March, latest 30 April, N = 45). Mean clutch size was 2.32 (N = 19). Hatching success was 91% (N = 33 eggs from 14 clutches). Mean brood size at hatching was 2.14 (N = 14). Eighty-nine percent of the territorial pairs laid eggs (N = 37) and 72% raised at least one chick to fledging (N = 100). Mean number of fledged young was 1.07 per territorial pair (N = 100), 1.11 per reproductive pair (N = 33), and 1.49 per successful pair (N = 72), with no significant differences among years. Diet was dominated by medium to small passerines, small mammals, and snakes. Recorded density and productivity were comparable and often higher than those reported for other European populations. Human persecution was high until the 1970s, but is currently unimportant. Future conversion of young coppice stands to mature forest could further favor pre-Alpine populations of Common Buzzards.