Ruffed Grouse Metabolic Rate and Temperature Cycles

Abstract

We measured the effects of temperature and wind on ruffed grouse (Bonasa umbellus) metabolic rates in an open-circuit respiration system with a closed-circuit wind tunnel. Metabolic heat production was linearly related to operative temperature (Te) below a lower critical temperature of 1.5 ? 0.99 (SE) C. Standard metabolic rate was 3.2 + 0.11 W (66.1 kcal/day) for a grouse of mean weight (607 g). Metabolic rate was related linearly to wind speed 05. The regression predicting net metabolic heat production (metabolic heat production evaporative cooling [M E]) was 3.1589 0.1176T, + 0.4141(wind speed)s5 (r2 = 0.98, P mean low nocturnal cloacal temperature (38.3 + 0.54 C) (P = 0.006). J. WILDL. MANAGE. 52(3):450-453 Ruffed grouse are distributed throughout north temperate and subarctic North America (Aldrich 1963) where winter thermostatic energy demands are potentially high. Grouse may feed frequently (Thomas et al. 1975) or use fat reserves (Norman and Kirkpatrick 1984) to meet winter metabolic demands. Rasmussen and Brander (1973) reported effects of cold temperatures on ruffed grouse metabolic rates under free convection (no wind). Effect of forced convection on heat loss by birds has been estimated from predictions based on heat transfer theory of cylinders and flat plates (Calder and King 1974, Robinson et al. 1976). Only a few studies have directly measured effects of forced convection on birds (Gessaman 1972, Robinson et al. 1976, Bakken et al. 1981), and none have been on galliforms. Most birds exhibit daily cyclical changes of 1-3 C body temperature between active and inactive periods (Calder and King 1974). This variation may increase with food deprivation or cold exposure (Calder and King 1974, Chaplin 1976, Bucher and Worthington 1982). Body temperature of ruffed grouse has been reported (Rasmussen and Brander 1973), but cyclic fluctuations or response to cold temperatures have not been measured. We report on effects of forced convection and perature on the metabolic heat production of ruffed grouse. We also measured daily fluctuations in body temperature and changes due to cold exposure. H. C. Gerhardt, J. Maruniak, and the Division of Biological Sciences, University of MissouriColumbia provided equipment necessary for this study. We thank D. E. Figert, D. E. Hoffman, B. J. Wilson, and C. S. James for assistance with various aspects of this study. M. R. Ryan and T. V. Dailey reviewed this manuscript. Financial support for this study was provided by the Ruffed Grouse Society and the Missouri Department of Conservation. This is Contribution 10382 of Missouri Agricultural Experiment Station ProjThis content downloaded from 157.55.39.45 on Fri, 02 Sep 2016 05:31:36 UTC All use subject to http://about.jstor.org/terms J. Wildl. Manage. 52(3):1988 GROUSE METABOLIC RATES * Thompson and Fritzell 451 ect 189 and the Missouri Cooperative Fish and Wildlife Research Unit (U.S. Fish and Wildl. Serv., Mo. Dep. Conserv., Univ. Missouri-Columbia, and Wildl. Manage. Inst., cooperating).