Autumn diet of lesser snow geese staging in northeastern Alaska

Abstract

The coastal plain of the Arctic National Wildlife Refuge (ANWR) is used by lesser snow geese ( Chen caerulescens caerulescens ) in autumn for premigratory staging. To better understand the potential impacts of human disturbance on snow geese, we investigated species composition of, and temporal and age-related variation in, their diet during staging. Depending on age and time of collection, between 35.2 and 94.1% of the diet (aggregate percent wet mass, n = 75) consisted of 2 species of plants; underground stems of tall cotton-grass ( Eriophorum angustifolium ), and aerial shoots of northern scouring rush ( Equisetum variegatum ). The diet varied between August and September ( P = 0.0089), morning and afternoon ( P < 0.0001), but not between age classes ( P = 0.066). Throughout staging, snow geese consumed more tall cotton-grass during the afternoon than during the morning ( P < 0.05). Tall cotton-grass was a larger component of the afternoon diet in September than in August ( P < 0.05). In September, snow geese consumed more northern scouring rush in the mornings than in the afternoon ( P < 0.05). Nighttime freezing, interspecific differences in nutritional quality, and plant senescence likely constrained the diet of snow geese to a small number of food items. Because alternative foods may not be available, human disturbance should be minimized in areas that provide these forage species.