FACTORS INFLUENCING THE SIZE OF SOME INTERNAL ORGANS IN RAPTORS

The size of the small intestine, stomach, kidney, liver and heart were compared among raptor species and considered in relation to hunting s trategy and body size. Species relying on rapid acceleration and maneu verability to capture prey in flight, such as sparrowhawk (Accipiter n isus), goshawk (A. gentilis), and peregrine (Fake peregrinus), had the smallest digestive tracts for their size. Species depending more on s oaring flight which do not need fast acceleration to capture prey, suc h as common buzzard (Buteo buteo), red kite (Milvus milvus), and Europ ean kestrel (Falco tinnunculus), had heavy digestive organs. In the St rigiformes, the same relationship was found, and species which hunt by active flight, such as barn owl (Tyro alba), and long-eared owl (Asio otus), had significantly lighter digestive tracts than the tawny owl (Strix aluco), a species which mainly hunts from a perch dropping onto its prey from above. Body condition was positively correlated with or gan weights, including the heart, but to a lesser extent with linear m easures of size such as intestine length.