Rozenfeld S.B., Sheremetev I.S., Baranyuk V.V.
Zoologicheskiy zhurnal 2017; 96(5): 511-521
The Lesser Snow Goose (Anser caerulescens caerulescens) is one of the most abundant geese globally. Its nesting distribution area which mostly lies in North America is presently expanding, with the numbers over the last 50 years grown from 1 to 15 million. Yet this goose species which has been exterminated in Eurasia fails to recover its historical range. The only large breeding colony in Eurasia has persisted on Wrangel Island, where the birds share food resources with ruminants. To find out what prevents the geese from dispersal and the establishment of new colonies on the island, we estimated the trophic niche overlap and competitive advantages in habitat choice. We show that ruminants are stronger trophic competitors to geese, while in most of the habitat types associated with the goose colony the level of trophic competition and/or resource shortage is higher than in post-colonial ones, where the resources are more diverse and abundant. We conclude that, in the present conditions of goose numbers growth on Wrangel Island, neither the restoration of extinct nor the initiation of new colonies is hampered by resource shortage and/or the stronger competitors (ruminants). The factors related to the distribution of food resources and to competition fail to determine the choice of a nesting site. This probably concerns arctic Eurasia in general.
