Dissertation Research: Repeatability of Heart Rate During Natural Migratory Flight in a Small Passerine Bird

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Broader Impacts The recent success of Sony Pictures film Winged Migration clearly demonstrates that the fantastic annual movements of literally billions of birds around the world can capture human interest and imagination like few other natural events. Migratory birds are an important part of ecosystems all over the world, yet the places where these birds live are being destroyed or changed and humans will have to learn more about them if they want to prevent their extinction. A key component of migration is the movement itself; what happens once the birds are in the air. Atmospheric conditions, individual size and shape and other factors such as health and experience should all affect the energy used during migratory flight and thus affect when and where birds stop to refuel. The work proposed here, particularly the development of an atmospheric model to examine the effects of wind, temperature and turbulence on energy use during flight, is a first step in understanding what determines the energetic cost of migratory flight. Understanding the effects of atmospheric conditions on migratory strategies may become particularly important for the average backyard birder as the global climate changes and migratory birds are forced to adapt. Intellectual Merit Recent technological developments have resulted in ~1g radio transmitters that allow scientists to measure the heart rates of small (~30g) birds. Since energy expenditure can be calculated from heart rate, it is possible to measure how much energy birds use while flying naturally, in the wild. The work proposed here will involve measuring the amount of energy small songbirds use during migratory flight and examining differences in energy use between individuals to better understand the costs of migration and to test certain predictions of aerodynamic theory about wing design. Testing these predictions will make it possible to refine models of avian flight and may serve to highlight a mechanism by which evolution has shaped the wings of many bird species. Whenever possible, data for individual birds will be obtained during two flights so that effects of variables that do not change between flights such as wing shape can be separated from the effects of variables that do change such as atmospheric conditions and body mass. The data that will be gathered in the course of this work has never been collected before simply because the technology has not been available; it will nicely complement studies of migratory physiology and behavior performed in wind tunnels or on birds captured during migration.