Summer Feeding Ecology of Lesser Snow Geese

Changes in the characteristics of the available vegetation at the mouth of the McConnell River, N.W.T. (60050'N, 94025'W), during the arctic summer were measured in 1971 and 1973. The concurrent variations in the feeding behavior of adult lesser snow geese (Chen caerulescens) were measured in 1973. Standing crop of vegetation in both grazed and ungrazed sites reached a maximum in the first week of August. The crude protein content of ungrazed vegetation showed a maximum value in late July, with a rapid decline in August. Grazed vegetation showed a similar rise, but with little decline in protein content in August. Snow geese and their goslings had access to a food supply increasing both in quantity and quality during the critical post-incubatory period. In this period adult female geese spent 17 hours per day feeding, probably as much time as was physically possible. Other parameters of feeding behavior varied predictably with the changes in vegetation characteristics. J. WILDL. MANAGE. 41(1):48-55 Members of the Hudson Bay population of lesser snow geese breed in colonies on coastal, tundra marshes (Cooch 1961). Throughout the summer, breeding adults feed almost exclusively on the green shoots of Gramineae, Cyperaceae, and Juncaceae. Arctic grasslands traditionally have been considered to have a low annual primary productivity and a low vegetational nitrogen content (Russell 1940, Wilson 1954, Bliss 1971). Paired adults arrive on the breeding grounds in late May or early June. Winter snow rarely melts by this time. Nesting starts as soon as suitable sites are available. There is little feeding by nesting adults during incubation, and females may lose more than 30 percent of their body weight during this period-including a large proportion of their breast muscle (Ankney 1974:102-107). This protein drain is exacerbated further by a major molt that occurs within 3 weeks of the end of incubation. Breeding geese must recover their lost body weight, replace their flight feathers, and prepare for southward migration in a twomonth period. They must do this while feeding on what is considered to be a nutrient-poor food supply. Compared to most grazing vertebrates, geese have a simple alimentary tract. Vegetation passes through the gut in 2 to 4 hours (Marriott and Forbes 1970, Ziswiler and Farner 1972:397), and large plant fragments are visible in the faeces. This rapid passage of food leaves little opportunity for any digestive process more complex than the simple absorption of cell solutes. Mattocks (1971) found no evidence of cellulose digestion in the digestive caecae of Anser