Energetics of the Canada Goose

Abstract

Measurements of food use in captive Canada geese (B. canadensis interior) over 3-4 day periods at constant temperatures showed that existence metabolism (Mkcal = kcal/bird per day) increased with decreases in temperature (T = .degree.C) as: Mkcal = 511 - 4.983T in males at 10- and 15-h photoperiods and Mkcal = 497 - 4.709T in a female at 15-h photoperiod. The metabolizable energy coefficient averaged 75.6%. Lower limits of temperature tolerance were below -40.degree. C and upper limits approximately +41.degree. C. Geese held out-of-doors exhibited many of the same fluctuations in weight during the year as occurs in wild populations. The 1st 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 g/day in body weight was correlated with a change of 3.4 kcal/bird per 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.