Abstract: Doctoral dissertation examining the influence and use of spread-winged behavior in the thermoregulation of two related avian species, the anhinga and the double-created cormorant. Dissertation Discovery Company and University of Florida are dedicated to making scholarly works more discoverable and accessible throughout the world. This dissertation, "Environmental and Behavioral Influences on the Comparative Energetics of Anhingas Double-crested Cormorants and Flightless Cormorants" by Willard W. Hennemann, was obtained from University of Florida and is being sold with permission from the author. A digital copy of this work may also be found in the university's institutional repository, IR@UF. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation.