FEEDING ECOLOGY OF NESTING GREATER SNOW GEESE

Spring body condition is an important determinant of reproductive succ ess in arctic-nesting geese. However, greater snow geese (Chen caerule scens atlantica) are unlike other geese in that they feed heavily duri ng the laying period and rely minimally on stored nutrient reserves. B ecause 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 Terri tories. I assessed diet and food consumption by examining esophageal c ontents and measuring the ingesta mass of geese collected by shooting. I also evaluated food quality by determining protein and fiber conten t of food plants collected at the same time. Ingesta mass of pre-layin g/laying females did not differ (P > 0.05) from that of geese collecte d in southern Quebec during spring staging, a period of high food inta ke 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, Sch euchzer's cottongrass (Eriophorum scheuchzeri), arctic willow (Salix a rctica), and stems of water sedge (Carex aquatilis var. stans) compris ed the rest. Grasses, willow, cottongrass, and oxytrope were high in p rotein content (greater-than-or-equal-to 20%), whereas grasses, cotton grass, sedge (stems), and willow were low in acid detergent fiber (< 2 5%). Emerging leaves of willow were potentially the most nutritious fo od. I suggest that, in addition to body condition upon arrival on the breeding grounds and availability of nesting sites, availability and q uality of feeding sites during pre-laying and laying are also factors that may explain annual variation in productivity of several species o f arctic-nesting geese.