Journal
ECOLOGY
Volume 93, Issue 1, Pages 122-130Publisher
WILEY
DOI: 10.1890/11-0385.1
Keywords
Eudyptes filholi; Eudyptes moseleyi; geolocation; habitat use; niche theory; nonbreeding period; penguins: resource partitioning; space segregation; stable isotopes; time segregation: trophic ecology
Categories
Funding
- ANR [07 Biodiv]
- Institut Polaire Francais Paul-Emile Victor [394]
- Terres Australes et Antarctiques Francaises
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Ecological niche theory predicts segregation mechanisms that mitigate potential competition between closely related organisms. However, little is known outside the breeding season, when central-place foraging animals may move on larger scales. This study tested for segregation mechanisms within the same 2007 inter-breeding period on three neighboring populations of avian predators from the southern Indian Ocean: Eastern Rockhopper Penguins Eudyptes filholi from Crozet and Kerguelen and Northern Rockhopper Penguins E. moseleyi from Amsterdam. Using state-of-the-art geolocation tracking and stable isotope analysis techniques, we quantified and compared the ecological niches in time, space, and diet. The three populations showed large-scale movements over deep oceanic waters near the Subantarctic Front, with generally little individual variation. The two neighboring populations of Eastern Rockhopper Penguins showed strikingly distinct distribution in space, while foraging in similar habitats and at the same trophic level (crustacean-eaters). In contrast, Northern Rockhoppers showed marked spatial overlap with birds of the sibling Eastern species, but their temporal delay of two months enabled them to effectively avoid significant overlap. Our results highlight parsimonious mechanisms of resource partitioning operating at the population level that may explain how animals from neighboring localities can coexist during the nonbreeding period.
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