Basal Metabolic Rate in the Gray Wolf in Poland

Basal metabolic rate (BMR) was measured in 12 gray wolves (Canis lupus) (t body wt = 33.0 kg) in winter. The BMR averaged 8.08 liters O,/hour; resting metabolic rate after feeding was about 45% higher. It is suggested that the factorial metabolic scope value (Vo2max/BMR) in the wolf is at least 3 x higher than an average for various mammals and may constitute an adaptation to the predatory way of life. J. WILDL. MANAGE. 51(4):800-801 Measurements of BMR provide a baseline to estimate energy requirements of free-living animals. These measurements are fundamental to a quantitative analysis of predator-prey interactions. BMR values are available for several species of canids (Hennemann et al. 1983). However, BMR has not been measured in the gray wolf, the largest and most widely distributed species of its family. Only very rough estimates of energy requirements of wolves have been made (Mech and Frenzel 1971, Kolenosky 1972, Mech 1977). We thank J. Weiner for useful comments on the manuscript, R. Tertil for his contribution to the final condition of the manuscript, and T. Kapuicinski for assistance in handling wolves. This study was supported by Grant MR-II-19. MATERIALS AND METHODS Twelve captive-born wolves were used in the metabolic measurements conducted in southeastern Poland in January 1986. The wolves, aged 1-12 years, represented both sexes and a wide range of body weights (Table 1). The animals were kept outdoors in large (100-400 m2) enclosures under quasi-natural conditions and fed a diet of raw venison. Wolves were fasted for 48-72 hours before BMR measurements. Animals were confined in metal cages (120 x 40 x 80 cm), weighed, and pl ced in a darkened room. The cages were covered by a plastic respiratory chamber. Atmospheric air was pumped through the respiratory chamber at flow rates between 37 and 39 liters/min (STPD). Calcium chloride was used to absorb water vapor from the excurrent airflow and the fractional concentration of 02 was measured with a Spirolyt II paramagnetic oxygen analyzer. The analyzer was calibrated against gas mixtures supplied by the manufacturer. The rate of 02 consumption was calculated using appropriate formulas (Fedak et al. 1981), assuming the respiratory quotient values of fasted and fed wolves are 0.7 and 1.0, respectively (Kleiber 1961). Each experiment lasted 24 or 48 hours, and O2-consumption measurements were performed at 2-4-hour intervals and lasted 0.5-2 hours. The measurements were carried out at temperatures between 3 and 25 C. After 12 or 24 hours from the start of an experiment, wolves were given about 1.5 kg of venison and the recordings of 02 consumption were continued. The results obtained were converted to standard conditions (STPD) and expressed in liters O2/hour. The statistical significance (P = 0.05) of differences between BMR's of males and females, and between adult and young, was calculated by analysis of covariance. Table 1. Mean (.R + SD) body weight (BW), basal metabolic rate (BMR), and the after-feeding resting metabolic rate (RMR) in captive-born gray wolves in southeastern Poland, 1986. BW BMR RMR (kg) (10,/hour) (10,/hour)