Seasonal and Local Weights of Alaskan Spruce Grouse

Abstract

Alaskan spruce grouse (Canachites canadensis) undergo 2 periods of weight loss, once in winter and again either in spring (males) during the time of intense display or in summer (females) during incubation and brood rearing. Males regain their former weight by August, but hens who have reared broods do not recover their weight until October. Juveniles weigh less than adults in autumn and winter, and these differences are maintained into the summer. A cline of increasing weights exists in populations from Washington northward through Alberta, coastal Alaska, and interior Alaska. J. WILDL. MANAGE. 43(1):176-183 Weights of animals are often useful to ecologists in interpreting life history characteristics, and even evolutionary strategies. Wiley (1974), for example, suggests that body size has played an important role in shaping the social organizations in the Tetraonidae. Such interpretations require accurate data on weights and on the variables affecting them. Zwickel and Brigham (1974) reported on autumn weights of spruce grouse (C. c. franklinii) in Washington, and Pendergast and Boag (1973) discussed seasonal variation in weights of C. c. canadensis in Alberta. Here we summarize geographical and seasonal weight trends in the northern part of the species'