THE BREEDING PERFORMANCE OF THE BUZZARD BUTEO-BUTEO IN ARGYLL, SCOTLAND AND A COMPARISON WITH OTHER AREAS IN BRITAIN

The laying dare, clutch size, brood size and number of fledged young w ere recorded from Buzzard nests at several study areas in mid-Argyll. These data are compared with other published studies to see if there a re regional trends in breeding biology in Britain. Laying dates are re markably constant throughout Britain. There are, however, highly signi ficant differences in clutch size between study areas. These do not fo llow any latitudinal gradient and it is likely that local factors such as habitat and prey availability are more important determinants of c lutch size. In particular clutch size was found to be low in areas whe re Rabbits were scarce and birds were an important component of the di et. There were also marked differences in hatching and fledging succes s between different areas in Britain. Buzzards in Argyll, despite layi ng comparatively small-sized clutches, have among the highest fledging success of any area. This is largely due to high egg survival. Human predation is unimportant in Argyll, but in some other areas of Britain it contributed to reduced breeding success.