Sympatric Breeding Auks Shift between Dietary and Spatial Resource Partitioning across the Annual Cycle |
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Authors: | Jannie Fries Linnebjerg Jér?me Fort Tim Guilford Anna Reuleaux Anders Mosbech Morten Frederiksen |
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Institution: | 1. Department of Bioscience, Aarhus University, Roskilde, Denmark.; 2. Department of Zoology, University of Oxford, Oxford, Oxfordshire, United Kingdom.; 3. Arctic Research Centre (ARC), Aarhus University, Aarhus, Denmark.; CNRS, Université de Bourgogne, France, |
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Abstract: | When species competing for the same resources coexist, some segregation in the way they utilize those resources is expected. However, little is known about how closely related sympatric breeding species segregate outside the breeding season. We investigated the annual segregation of three closely related seabirds (razorbill
Alca
torda
, common guillemot
Uria
aalge
and Brünnich’s guillemot
U
. lomvia
) breeding at the same colony in Southwest Greenland. By combining GPS and geolocation (GLS) tracking with dive depth and stable isotope analyses, we compared spatial and dietary resource partitioning. During the breeding season, we found the three species to segregate in diet and/or dive depth, but less in foraging area. During both the post-breeding and pre-breeding periods, the three species had an increased overlap in diet, but were dispersed over a larger spatial scale. Dive depths were similar across the annual cycle, suggesting morphological adaptations fixed by evolution. Prey choice, on the other hand, seemed much more flexible and therefore more likely to be affected by the immediate presence of potential competitors. |
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