TitleRespiratory evaporative water loss during hovering and forward flight in hummingbirds
Publication TypeJournal Article
Year of Publication2012
AuthorsPowers, DR, Getsinger, PW, Tobalske, BW, Wethington, SM, Powers, SD, Warrick, DR
JournalComparative Biochemistry and Physiology a-Molecular & Integrative Physiology
Type of ArticleJournal Article

Hummingbirds represent an end point for small body size and water flux in vertebrates. We explored the role evaporative water loss (EWL) plays in management of their large water pool and its use in dissipating metabolic heat. We measured respiratory evaporative water loss (REWL) in hovering hummingbirds in the field (6 species) and over a range of speeds in a wind tunnel (1 species) using an open-circuit mask respirometry system. Hovering REWL during the active period was positively correlated with operative temperature (T-e) likely due to some combination of an increase in the vapor-pressure deficit, increase in lung ventilation rate, and reduced importance of dry heat transfer at higher T-e. In rufous hummingbirds (Selasphorus rufus; 3.3 g) REWL during forward flight at 6 and 10 m/s was less than half the value for hovering. The proportion of total dissipated heat (TDH) accounted for by REWL during hovering at T-e>40 degrees C was

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