Comparison of the nutrient contents of the principal forage plants utilized by lesser snow geese on summer breeding grounds.
Nutritional contents of preferred and alternative forage species at La Pérouse Bay, Manitoba were determined, and these values were compared with the nutritional requirements of lesser snow goose (Anser caerulescens caerulescens) goslings. Goslings and adult lesser snow geese on the breeding grounds require large amounts of nutrients in summer for growth and to build reserves for autumnal migration. As the birds are essentially herbivorous, forage of high nutritional quality is required to meet nutritional demands. Preferred forage species (Carex subspathacea, Puccinellia phryganodes) during the post-hatch period in summer at La Pérouse Bay, had a higher nutrient content than alternative forage species (Festuca rubra, Calamagrostis deschampsioides, Carex aquatilis, C. × flavicans). Geese were able to detect forage of high nutritional quality. The three elements that were potentially in short supply in the forage for the growth of geese were nitrogen, calcium, and phosphorus. Quantities of these elements in the preferred salt-marsh forage broadly met the estimated dietary requirements of the geese. Amounts of potassium, magnesium, sodium and manganese in both preferred and alternative forage species were adequate for the growth of the geese. These estimates were based on the requirements of domestic geese. The reduced availability of the preferred salt-marsh forage species and the increased use of alternative forage species were associated with a long-term decline in gosling size. Elsewhere in the Arctic where these six forage species do not occur or are infrequent, goslings of lesser snow geese fledged successfully, which indicates that there are guilds of forage species capable of meeting the nutritional demands of the birds. Two such species, Dupontia fisheri and Arctophila fulva, are known to have nutrient contents comparable to the salt-marsh graminoids examined in this study.