Shifting to an energy-poor diet for nitrogen? Not the case for wintering herbivorous Lesser White-fronted Geese in China

Geese often forage on mid-winter foods that fail to satisfy daily energy needs, but they may do so to acquire other nutrients, such as nitrogen. We tested this hypothesis by evaluating nitrogen budgets, namely the balance of nitrogen income against expenditure, of wintering Lesser White-fronted Geese Anser erythropus feeding at two sites within East Dongting Lake, China, where they could and could not balance daily energy budgets. Geese could balance nitrogen budgets in energy-rich habitats but were less able to do so in habitats where they failed to balance energy budgets. This study presents the first full nitrogen budget for a wintering goose species, and suggests that, rather than acting as a source of nitrogen, use of energy-poor but undisturbed habitats may represent a refuge from human disturbance at other habitats.