FEEDING ECOLOGY OF NESTING GREATER SNOW GEESE

Spring body condition is an important determinant of reproductive success in arctic-nesting geese. However, greater snow geese (Chen caerulescens atlantica) are unlike other geese in that they feed heavily during the laying period and rely minimally on stored nutrient reserves. Because laying is a period of high nutrient requirement for females, I determined the amount, species composition, and nutritional quality of food consumed by geese while nesting at Bylot Island, Northwest Territories. I assessed diet and food consumption by examining esophageal contents and measuring the ingesta mass of geese collected by shooting. I also evaluated food quality by determining protein and fiber content of food plants collected at the same time. Ingesta mass of pre-laying/laying females did not differ (P > 0.05) from that of geese collected in southern Quebec during spring staging, a period of high food intake and rapid fat accumulation. Roots and rhizomes of Maydell oxytrope (Oxytropis maydelliana), alpine bistort (Polygonum viviparum), grasses, and sedges accounted for 40% of the diet; young leaves of grass, Scheuchzer's cottongrass (Eriophorum scheuchzeri), arctic willow (Salix arctica), and stems of water sedge (Carex aquatilis var. stans) comprised the rest. Grasses, willow, cottongrass, and oxytrope were high in protein content (greater-than-or-equal-to 20%), whereas grasses, cottongrass, sedge (stems), and willow were low in acid detergent fiber (< 25%). Emerging leaves of willow were potentially the most nutritious food. I suggest that, in addition to body condition upon arrival on the breeding grounds and availability of nesting sites, availability and quality of feeding sites during pre-laying and laying are also factors that may explain annual variation in productivity of several species of arctic-nesting geese.