Energetics of the Canada Goose

Abstract

Measurements of food use in captive Canada geese (Branta canadensis interior) over 3to 4-day periods at constant temperatures showed that existence metabolism (Mkcal = kcal/bird/day) increased with drop in temperature (T = ?C) as: Mkcal = 511 4.983T in males at 10and 15-hour photoperiods and Mkcal = 487 4.709T in a female at 15-hour photoperiod. The metabolizable energy coefficient averaged 75.6%. Lower limits of temperature tolerance were below -40 C and upper limits approximately +41 C. Geese held out-of-doors exhibited many of the same fluctuations in weight during the year as occurs in wild populations. The first phase of annual molt involved replacement of flight feathers, and at this time weight reached its minimum. Replacement of body feathers began as flight feathers neared full growth and body weight increased. Maximum weights were attained in April. A change of 1 gram/day in body weight was correlated with a change of 3.4 kcal/bird/day. Total diel and nocturnal cage activity increased along with weight during the migration periods. Carcass analyses showed that body lipids became reduced at low temperatures and body water at high temperatures. Minimum lipid reserves occurred in molting geese with maximum levels in spring. A nearly constant level of existence metabolism and potential productive energy is maintained by migration between breeding and wintering areas. J. WILDL. MANAGE. 46(3):588-600 The present study, conducted from 1959 to 1963, was designed to investigate the energy economy of the Canada goose in relation to variations in temperature and photoperiod to which it is subjected during its annual cycle. The objective was to obtain direct quantitative information of the role of energy in limiting distribution and regulating migration. The use of experimental data from birds under controlled conditions for explaining behavior of free-living birds under natural conditions must be made with caution but provides an understanding of underlying physiological potentials. We thank H. C. Hanson of the Illinois Natural History Survey who, in addition to many valuable suggestions, made the geese available, classified them to sex and age, and supplied some of the experimental equipment. D. G. Raveling provided helpful suggestions for revising the final manuscript. Appreciation is expressed to R. Williams for help in analyzing portions of the results and to A. Kosowski, J. B. Olson, J. Zar, N. Arnoldi, F. H. Blackmore, and D. Parrack for their contributions to various portions of the experimental work. L. C. Bliss and J. Kastelic made laboratory facilities available. This research was financed by a grant from the National Science Foundation to S. C. Kendeigh.