Metabolic rate and evaporative water loss at different ambient temperatures in two species of fox: the red fox (Vulpes vulpes) and the Arctic fox (Alopex lagopus).
1. Resting metabolic rate (RMR) and evaporative water loss (EWL) of adult red and arctic foxes were determined over ambient temperature (Ta) ranges of -13-37 degrees C and -5-30 degrees C as oxygen consumption and amount of water in expired air using an open flow system. 2. The average RMR was 2.60 +/- 0.14 W/kg for the winter red fox, 2.59 +/- 0.14 W/kg for the summer red fox, and 2.35 +/- 0.11 W/kg for the winter arctic fox. 3. The rate of increase of RMR was significant (P less than 0.05) only for Ta range above 27 degrees C. The slopes for this Ta range were 0.152 for the winter red fox, and 0.283 for the winter arctic fox. 4. The upper critical temperature (Tuc) of the red fox is probably between 30 and 32 degrees C. The Tuc of the arctic fox is probably between 26 and 28 degrees C. The lower critical temperatures (Tlc) were not reached. 5. A strong linear relationship between the EWL and Ta was found for Ta range above 27 degrees C. The slopes for this Ta range were 0.523 for the winter red fox, and 1.025 for the winter arctic fox. 6. Probably, there are neither significant intraspecific seasonal nor interspecific differences in the RMR and EWL. The two species seem to differ only in their critical temperatures.
Klir
J J
JJ
Department of Physiology and Biophysics, University of Illinois, Urbana 61801.
Heath
J E
JE
D000818:Animals; D004734:Energy Metabolism; D005589:Foxes / Q000378:metabolism*; D006197:Hair; D008297:Male; D010100:Oxygen / Q000378:metabolism; D012621:Seasons; D013045:Species Specificity; D014867:Water / Q000378:metabolism*
D014867:Water; D010100:Oxygen