INFLUENCE OF WIND-SPEED ON SAGE GROUSE METABOLISM

We measured the effect of wind speed on the metabolic rate of six adul t sage grouse (Centrocercus urophasianus) with indirect respiration ca lorimetry at ambient temperatures above, near, and below the lower cri tical temperature. There was a significant effect (P < 0.05) of temper ature on metabolic rate at all wind speeds, and a significant effect ( P < 0.05) of wind speed on metabolic rate for temperatures less than o r equal to 0 degrees C. Wind speed had a more pronounced effect on met abolism at temperatures below the lower critical temperature for sage grouse. Metabolic rates measured at wind speeds of greater than or equ al to 1.5 m/s were significantly higher than those measured at wind sp eeds < 1.5 m/s. Multiple regression analysis of wind speed (u; m/s) an d temperature (T-a; degrees C) on metabolism (MR; mL O-2 . g(-1). h(-1 )) yielded the equation MR = 0.0837 (u) - 0.0248 (T-a) + 0.5444. The p redicted cost of thermoregulation at conditions of -5 degrees C and u = 1.5 mis was about 1.5 x standard metabolic rate; half the increase w as due to wind. Measurements of wind speed in sagebrush (Artemisia spp .) stands indicate that such habitat effectively reduces wind speed to < 1.5 m/s. Microhabitat value should be recognized in the management of sagebrush stands.