Winter Weight Dynamics, Grain Consumption and Reproductive Potential in Canada Geese

Abstract

Hanson (1962) suggested that late winter weight loss of Canada geese (Branta canadensis) is a normal situation in which geese enter a refractory period that later facilitates rapid weight gain during vernal migration. To examine this hypothesis, winter weight dynamics, grain intake, and indices of physical and reproductive condition were compared for 13 caged Canada Geese maintained on three feeding schedules: (1) ration unlimited January through 11 May; (2) ration restricted during January/February but unlimited thereafter; and (3) ration restricted throughout the trial but quantity increased progressively from March through May. Geese fed freely did not reduce their intake during late winter, but maintained food consumption and gained weight from January through April. The data suggest that late winter weight loss in these geese is not necessitated by endogenous factors, but instead reflects food availability and ambient conditions. Weight loss in February or March does not elicit rapid weight gain in April. Reduced intake in January and February ultimately had little effect on breast and organ weights, carcass lipid and protein, and indices of reproductive potential. However, the reproductive potential of two females kept on restricted intake through May possibly was affected, as indicated by lighter ovary weights, with fewer and smaller follicles.