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UBC Theses and Dissertations

Form and function in hummingbird flight Skandalis, Dimitri Ariel


The extent to which locomotor adaptations depend on evolution of morphological form or kinematic function remains an open question. Hummingbirds are a speciose group with exceptional aerial abilities across a large range of habitats, making them attractive models for biomechanical studies of coupled form and function. Here, I investigate the origin of hummingbird flight performance among and within species, and within individuals. I develop a novel biomechanical framework adapted from aerodynamic principles, and find that a weight-support strategy thus far only identified among hummingbird species is likely a response to selection for constant, mass-independent hovering and burst performance. Within species, hummingbirds exhibit an alternative weight-support strategy that instead results in reduced flight performance in larger individuals. I next develop experimental and analytical techniques to investigate the time- and behaviour-dependence of wing morphology and kinematics. Within individuals, flight performance depends on fine adjustments to wing kinematics and wing morphology, including wing twisting and cambering. I suggest that individual hummingbirds dynamically control their wing morphology to minimise the cost of flight rather than maximise force production, but can sacrifice flight efficiency to enable challenging flight behaviours. Wing morphing therefore offers flight control degrees of freedom that can be called upon as required. Taken together, I propose that evolution of wing form maximises average performance, but also maximises the scope for dynamic wing control.

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