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Trophic niche expansion during the non-breeding season in kelp gulls of known breeding colony
- Lisnizer, Nora, Yorio, Pablo
- Marine biology 2019 v.166 no.2 pp. 12
- Larus dominicanus, autumn, birds, breeding, carbon, feathers, foraging, habitats, nitrogen, population dynamics, stable isotopes, summer, winter, Argentina
- Year-round foraging strategies are key determinants of bird population dynamics. However, trophic ecology studies during the non-breeding period rarely focus on individuals from a known breeding colony, precluding links to demographic aspects of the target population or metapopulation. Using stable isotope analysis (δ¹⁵N, δ¹³C) of primary feathers moulted sequentially after breeding, we tested the trophic niche variation during the non-breeding seasons 2010 and 2011 in Kelp Gulls Larus dominicanus from a colony in coastal Patagonia (43º04′S, 64º29′W), Argentina. Isotopic niche position changed gradually from late summer to late autumn/early winter due to a progressive depletion in δ¹⁵N. In addition, niche spread showed a progressive expansion in the same study period. This niche expansion was consistent with the observed differences in the among-individual variability in feeding ecology suggested by niche metrics, being lower during the end of breeding compared to the non-breeding period. Low δ¹³C values of some feathers suggest that this expansion may be in part driven by the utilization of non-marine food resources/habitats by some individuals.