Winter energy requirements of blue grouse

Abstract

We measured the effects of temperature (T,) on the metabolic rate of 6 blue grouse (Dendragapus obscurus) during winter with indirect respiration calorimetry. The standard metabolic rate was 0.8 12 L O2 . (kg0.734)-1 h-' and was 24% higher than that predicted allometrically. The lower critical temperature (T,) of fasted grouse was -5°C; metabolism increased linearly below -5°C. The heat increment associated with a Douglas-fir (Pseudotsugu menziesii) diet lowered the 7;, by 5 "C. From -5 to -20°C, the metabolism of fasted and fed grouse increased by 30 and 12 % , respectively. A positive winter energy balance was predicted for blue grouse from estimates of the field metabolic rate and the consumption and assimilation rates of a Douglas-fir diet. PEKINS, P. J., GESSAMAN, J. A., et LINDZEY, F. G. 1992. Winter energy requirements of blue grouse. Can. J. Zool. 70 : 22 -24. Nous avons mesure les effets de la temperature (T,) sur le taux de metabolisme de six Tetras sombres (Dendragapus obscurus) au cours de I'hiver par calorimetric respiratoire indirecte. Le taux de metabolisme de base a Cte evalue a 0,812 LO2 . (kg-0.7")-' . h-I, valeur de 24% plus elevee que la valeur estimee d'aprks l'allometrie. Le seuil critique inferieur (T,) de tetras soumis a un jeQne etait de -5°C; le metabolisme augmentait de fagon lineaire aux temperatures inferieures a -5°C. L'augmentation de chaleur associee a un regime alimentaire de Sapin de Douglas (Pseudotsugu menziesii) abaissait le seuil 7;, de 5°C. Entre -5 et -20°C, le metabolisme augmentait de 30% chez les tetras soumis au jeQne et de 12% chez des tetras nourris. L'estimation du taux de metabolisme, de la consommation et du taux d'assimilation a un regime de Sapins de Douglas a permis de predire un budget energetique positif au cours de I'hiver chez le Tetras sombre. [Traduit par la redaction] Introduction Blue grouse (Dendragapus obscurus) in the Rocky Mountain region of the United States typically overwinter in open stands of Douglas-fir (Pseudotsuga menziesii) at elevations above 1830 m (Marshall 1946;Cade 1985;Stauffer and Peterson 1985). Normal climatic conditions during winter include nearly continuous winds and temperatures below freezing. Despite these conditions, winter mortality of blue grouse is probably minimal (Lewis and Zwickel 1982;Cade 1985), and the data of Redfield (1973) and Harju (1974) imply that blue grouse maintain or gain weight during winter, although no data are available for individual grouse. Blue grouse have apparently developed physiological and behavioral adaptations to effectively cope with the energetic demands of their winter environment.The winter occupation of high altitude, snowbound habitat by blue grouse requires autumnal migration to higher elevations, a behavior much in contrast to that of most northern homeotherms. Consequently, the maintenance of a favorable winter energy balance represents a unique ecological situation and adaptive strategy. Energetic studies are integral to the understanding of the winter ecology and adaptations of blue...

Winter space use and social behaviors of Chinese Grouse (Bonasa sewerzowi) at Lianhuashan mountains, Gansu, China

“…Sex effect in the movement patterns is also found in our study. During winter, mortality was high in both sexes, due to food shortage, predation and extreme weather conditions (Pekins et al 1992). The male-biased sex ratio in the population of Chinese Grouse may lead females to concentrate more on food intake in winter, because there is no danger of failing to pair in the next spring.…”

“…Deep snow in the forest limited ground food availability for White-tailed Ptarmigan in winter (Quick 1947). When energy is a limiting factor, extra energy loss was extremely adverse for winter survival (Pekins et al 1992). Our research showed that the variable snow depth with 1 cm change, the log of the ratio of the two probabilities P (M/R) and P (W/R) would increase by 0.6992, 0.2516, so with the higher snow depth, male Chinese Grouse would leave their territory and move to flocking area on the sunny slopes.…”

Microclimatic characteristics of blue grouse Dendragapus obscurus roost‐sites: influence on energy expenditure

“…Wind speed reductions of 70–90% are common at nocturnal, coniferous roost‐sites of many species of birds (Francis 1976, Kelty & Lustick 1977, Lustick 1980, Walsberg & King 1980, Keister et al 1985). The average wind speeds measured at nocturnal roost‐sites (<1.0 m/sec, see Table 2) were within the linear response of blue grouse metabolic rate (MR) to the square root of wind speed (0–2.75 m/sec) at T a 's of 5 to ‐15°C (Pekins 1988b). Because metabolic response to wind speed is non‐linear when plumage is penetrated by wind (Kelty & Lustick 1977, Hayes & Gessaman 1980, Walsberg 1985), the microclimate at roost‐sites prevented such substantial convective heat loss.…”

“…Roost‐site selection was apparently not dictated by ambient temperature (T a ) alone, because the mean T, was above the lower critical temperature of fed blue grouse (‐10°C, Pekins, Gessaman & Lindzey 1992), and T a varied only 1–2°C between roost sites and the control site. A substantial reduction of T a at roostsites has been found only in situations where local effects or a temperature inversion was present (Gyllin, Kallander & Sylven 1977, Yom‐tov, Imber & Otterman 1977).…”

The influence of season, temperature, and absorptive state on sage grouse metabolism

“…However, the winter TIC of male sage grouse is also higher than the TIC values of blue grouse (Dendragapus ohscurus; Pekins et al 1992) (-5°C) and rock ptarmigan (Lagopus mutus; West 1972) (-1.3"C), both of which are smaller than male sage grouse. Thus, body size alone does not determine TIC.…”