title: Diet dichotomy between two migrant seabirds breeding near a high Arctic polynya.
abstract: High Arctic polynyas are predictable areas of open water, which offer long-distance migrant seabirds a reliable source of food during a period when they have to replenish and accumulate energy for reproduction. Investigating the interaction between species nesting sympatrically in the vicinity of polynyas should provide insights into the role that such oceanographic features play for pre-breeding seabirds. We used stable isotopes (δ13C and δ15N) to compare the diet of two ground-nesting seabirds, Sabine's gull (Xema sabini) and Arctic tern (Sterna paradisaea), nesting on an island adjacent to a recurring polynya in the Canadian high Arctic in 2008 and 2009. We show that, unlike Arctic terns, the diet of Sabine's gulls appears to include a non-negligible amount of terrestrially derived prey during early incubation, and that overall both species segregate their dietary niche during pre-laying and early incubation.
authors.affiliation: Department of Biology, Acadia University, 15 University Drive, Wolfville, Nova Scotia, CanadaB4P 2R6; High Arctic Gull Research Group, 109 Kings Road, Bamfield, British Columbia, CanadaV0R 1B0.
authors.forename: Isabeau
authors.identifier: 0000-0001-6144-6135
authors.initials: I
authors.lastname: Pratte
authors.affiliation: High Arctic Gull Research Group , 109 Kings Road, Bamfield, British Columbia , Canada V0R 1B0.
authors.forename: Kelly A
authors.initials: KA
authors.lastname: Boadway
authors.affiliation: High Arctic Gull Research Group , 109 Kings Road, Bamfield, British Columbia , Canada V0R 1B0.
authors.forename: Shanti E
authors.initials: SE
authors.lastname: Davis
authors.affiliation: High Arctic Gull Research Group , 109 Kings Road, Bamfield, British Columbia , Canada V0R 1B0.
authors.forename: Mark
authors.initials: M
authors.lastname: Maftei
authors.affiliation: Department of Biology, Acadia University, 15 University Drive, Wolfville, Nova Scotia, CanadaB4P 2R6; High Arctic Gull Research Group, 109 Kings Road, Bamfield, British Columbia, CanadaV0R 1B0.
authors.forename: Mark L
authors.initials: ML
authors.lastname: Mallory
keywords: Arctic tern; Sabine's gull; incubation; niche segregation; stable isotopes