UC Berkeley

Hummingbirds are exceptional among vertebrates in their extreme flight capabilities. They are unique in their ability to not only sustain hovering flight, but also to fly backwards, dive at high speeds, and perform quick alternations in flight speed and body orientation. Such capabilities require hummingbirds to have large metabolic power reserve, mechanical power output, force production, and maneuverability. These features, along with the relative ease of working with hummingbirds in a laboratory setting, make them a particularly convenient model system to assess different aspects of flight mechanics. Hence, this thesis is broadly on the flight performance of Anna's hummingbirds (Calypte anna) (seen in the above figure), a hummingbird species found year-round on the University of California, Berkeley campus, with each chapter focusing on a different flight mode: hovering flight in ground effect (chapter 1), vertically ascending steady flight (chapter 2), vertically descending steady flight (chapter 3), and forward flight in an asymmetric flow (chapter 4). The overall goal of each chapter is to gain a greater understanding of the aforementioned flight modes (e.g. what are the kinematic correlates of each flight mode, or what are the limits that constrain such a flight mode), all of which have not been previously analyzed in any detail.