Bedard J. & Gauthier G. (1989) Comparative energy budgets of Greater Snow Geese Chen caerulescens atlantica staging in two habitats in spring. ARDEA 77 (1): 3-20

During a recent population increase, the high-arctic nesting Greater Snow Goose Chen caerulescens atlantica greatly expanded its spring staging habitat. Over two decades, the flock over-spilled from its traditional fresh-water Scripus marshes of the upper St. Lawrence River estuary into the salt-water Spartina marshes of the lower estuary. It also considerably expanded its use of neighbouring farmland. Concurrent studies revealed that the geese were completing the spring staging with substantially lower fat reserves in the recently invaded area. The present study was designed to identify the causes of these differences in the level of pre-breeding conditioning by making energy budgets covering the 6-week staging period in both habitats. There were profound differences in energy budgets between the two study sites, which was mainly caused by differences in digestibility of food plants (Spartina rhizomes 25%, Scirpus rhizomes 51%). An increased use of farmland and especially of cereal grains in the newly-invaded habitat, partly made up for the inadequacy of the Spartina rhizomes in supplying metabolizable energy. Under these circumstances, it is expected that the geese will further increase their dependence on agricultural plants in order to complete pre-breeding fattening.