COMPARISON OF THE NUTRIENT CONTENTS OF THE PRINCIPAL FORAGE PLANTS UTILIZED BY LESSER SNOW GEESE ON SUMMER BREEDING GROUNDS

1. Goslings and adult lesser snow geese on the breeding grounds requir e large amounts of nutrients in summer for growth and to build reserve s for autumnal migration. As the birds are essentially herbivorous, fo rage of high nutritional quality is required to meet nutritional deman ds. 2. Preferred forage species (Carer subspathacea, Puccinellia phryg anodes) during the post-hatch period in summer at La Perouse Bay, Mani toba, have a higher nutrient content than alternative forage species ( Festuca rubra, Calamagrostis deschampsioides, Carer aquatilis, C. x fl avicans). Geese appear able to detect forage of high nutritional quali ty. 3. 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 broa dly met the estimated dietary requirements of the geese. Amounts of po tassium, magnesium, sodium and manganese in both preferred and alterna tive forage species were adequate for the growth of the geese. These e stimates were based on the requirements of domestic geese. 4. The redu ced availability of the preferred salt-marsh forage species and the in creased use of alternative forage species are associated with a long-t erm decline in gosling size. Elsewhere in the Arctic where these six f orage species do not occur or are infrequent, goslings of lesser snow geese hedge successfully, which indicates that there are guilds of for age species capable of meeting the nutritional demands of the birds. T wo such species, Dupontia fisheri and Arctophila fulva, are known to h ave nutrient contents comparable to the salt-marsh graminoids examined in this study.