Does prey size affect predatorybehaviour of Kestrel ?



sample of IO rehabilitated kestrels Falco tinnunculus was tested immediately prior to release to ascertain whether their predatory behaviour was modified according to the type of prey the kestrel faced. The tests were carri ed out individually in captivity conditions, using either one laboratory agouti mouse weighing 12-15 g or one laboratory agouti rat weighing 48-60 g. The size ratio between the prey was then constantly of 1:4. The behavior displayed by the kestrels before either prey was c1early different, both prior to and after its catching. The rat elicited more conflict patterns, such as preening and movements on the perch, while this was hardly ever record ed during the rnouse-tests. There were instead no differences in the latency of predation and the technique used for grasping the prey. In contrast, the rat received more biting than the mouse, and the latency of ingestion, interpreted as the time span necessary to induce the death of the prey, was much longer when the rat was captured. The adaptive implication of such behaviour differences are discussed.