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キーワード:
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要旨:
The predatory behaviour of four owl species, tawny owl (Strix aluco), long-eared owl (Asio otus), little owl (Athene noctua) and barn owl (Tyto alba), was compared. The birds were wild individ- uals temporarily in captivity for rehabilitation and were tested be- fore release into an outdoor pen. Between four and ten birds per species were individually tested by offering a laboratory mouse used as prey. The resulting sequence of the predatory behaviour patterns was homogeneous among the species. The latency to at- tack was similar and there was a tendency to prefer direct attacks, i.e. landing onto the prey directly, instead of indirect ones, i.e. landing a few centimetres from the mouse. However, tawny owls used the former attack only. The various degrees of specialisation to hunt small mammals is reflected by the grip location: the barn owls strongly preferred to seize the mouse on the head, while the little owls preferred the trunk and the other species preferred ei- ther location. Similarly, after grasping the mouse tawny and long- -eared owls struck it with the beak, while the little owls per- formed strikes similar to bites. In contrast, barn owls performed a peculiar torsion of the neck region, instead of a beak strike. We interpret this pattern difference within a basically homogeneous behaviour sequence as evolutionary radiation due to species-spe- cific specialisation of feeding and hunting behaviour. KEY
