Skip to Main Content
U.S. Forest Service
Caring for the land and serving people

United States Department of Agriculture

Home > Search > Publication Information

  1. Share via EmailShare on FacebookShare on LinkedInShare on Twitter
    Dislike this pubLike this pub
    Author(s): Joseph L. Ganey; Russell P. Balda; Rudy M. King
    Date: 1993
    Source: Wilson Bulletin 105 (4) 645-656
    Publication Series: Miscellaneous Publication
    PDF: View PDF  (593 KB)


    We measured rates of oxygen consumption and evaporative water loss (EWL) of Mexican Spotted (Strix occidentalis lucida) and Great Horned (Bubo virginianus) owls in Arizona. Basal metabolic rate averaged 0.84 ccO2 . g-1 . h-1 for the Spotted Owl and 0.59 ccO2 . g-1 . h-1 for the Great Horned Owl, with apparent thermoneutral zones extending from 17.0-25.2°C for the Spotted Owl and 20.3-32.2°C for the Great Horned Owl. EWL increased exponentially with ambient temperature in both species, but the Great Horned Owl showed a greater ability to dissipate metabolic heat production at high temperatures than did the Spotted Owl. Body temperature of Spotted Owls was significantly higher above than below the upper critical temperature (25.2°C) whereas body temperature of Great Horned Owls did not differ significantly with ambient temperature. Gular flutter was first observed in Spotted Owls at 30°C and in Great Horned Owls at 37°C. The lower ability of the Spotted Owl to dissipate heat via evaporative cooling may partially explain its tendency to use habitats featuring cool microsites.

    Publication Notes

    • You may send email to to request a hard copy of this publication.
    • (Please specify exactly which publication you are requesting and your mailing address.)
    • We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
    • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.


    Ganey, Joseph L.; Balda, Russell P.; King, Rudy M. 1993. Metabolic rate and evaporative water loss of Mexican Spotted and Great Horned Owls. Wilson Bulletin 105 (4) 645-656


    Mexican spotted owl, Strix occidentalis lucida, great horned owl, Bubo virginianus, metabolic rate, evaporative water loss (EWL)

    Related Search

    XML: View XML
Show More
Show Fewer
Jump to Top of Page