SELECTION OF AVIAN PREY BY WINTERING SPARROWHAWKS ACCIPITER-NISUS IN SOUTHERN SCOTLAND

Sparrowhawks Accipiter nisus were studied hunting a wide range of avia n species during three winters on a small Scottish estuary to determin e which species were the most vulnerable to Sparrowhawk predation. Sel ection of avian prey was studied by comparing the proportions of diffe rent species among prey items found, with their proportions in the bir d population. Certain prey species were more vulnerable to Sparrowhawk predation: the relative vulnerability of a species remained reasonabl y consistent between winters. Sparrowhawks preferentially selected pre y of weight 51-150 g, with the most favoured weight of prey being 101- 150 g. There was a significant positive correlation between vulnerabil ity to predation and body weight of a prey species up to 150 g. Mean w eight of prey taken did not vary between winters. Relative conspicuous ness of a prey species was apparently not an important factor in deter mining vulnerability.