Abstract

The wing morphology of bats is very diverse, and may correlate with energetic, behavioural, and ecological demands. If these demands conflict, wing shape may reflect compromise solutions. In this study, we compared the wing morphology of two bats, Tadarida brasiliensis (Geoffroy, 1824) and Myotis chiloensis (Waterhouse, 1828), that differ in body size, habitat, and foraging behaviour. We analyzed features of biomechanical and energetic relevance, and sought evidence of compromise solutions to energetic, ecological, and behavioural demands. We found that wing span of both species conformed to expectations based on allometric relationships, but that although the wing area of M. chiloensis did not differ from predictions, the wing area of T. brasiliensis was lower. M. chiloensis possessed an unusually low second moment of area of the humerus. Wing form of M. chiloensis is consistent with highly maneuverable flight needed to live between shrubs and wooded habitats, and its low aspect ratio and low wing loading indicate a high energetic cost and a low flight speed, respectively. The low humeral second moment of area may be related to a reduction of wing mass and may result in decreased inertial power. In contrast, T. brasiliensis showed high aspect ratio and wing loading, characteristic of high speed, energetically economic flight.