MEPS 533:261-276 (2015)  -  DOI: https://doi.org/10.3354/meps11388

Foraging ecology during nesting influences body size in a pursuit-diving seabird

Rosana Paredes1,*, Rachael A. Orben2, Daniel D. Roby3, David B. Irons4, Rebecca Young5, Heather Renner6, Yann Tremblay7, Alexis Will5, Ann M. A. Harding8, Alexander S. Kitaysky5

1Department of Fisheries and Wildlife, 104 Nash Hall, Oregon State University, Corvallis, OR 97331-3803, USA
2Ocean Sciences Department, University of California Santa Cruz, Long Marine Lab, Santa Cruz, CA 95060, USA
3US Geological Survey-Oregon Cooperative Fish and Wildlife Research Unit, 104 Nash Hall, Oregon State University, Corvallis, OR 97331-3803, USA
4US Fish and Wildlife Service, 1011 East Tudor Road, Anchorage, AK 99503, USA
5Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775-7000, USA
6Alaska Maritime National Wildlife Refuge, U.S. Fish and Wildlife Service, Homer, AK 99603, USA
7Marine Biodiversity, Exploitation and Conservation, Institut de Recherche pour le Développement (IRD), UMR248 MARBEC, Avenue Jean Monnet, CS 30171, 34203 Sète cedex, France
8Environmental Science Department, Alaska Pacific University, 4101 University Drive, Anchorage, AK 99508, USA
*Corresponding author:

ABSTRACT: Causes and consequences of differences in seabird foraging strategies between breeding colonies are not well understood. We tested whether body size of a pursuit-diving seabird, the thick-billed murre Uria lomvia, differs between breeding colonies and, if so, how size differences can be understood in the context of differences in foraging behavior, habitat use, and breeding performance. We measured adult murres over 3 seasons (2008 to 2010) at 2 of the Pribilof Islands, St. Paul and St. George, located on the continental shelf of the Bering Sea at different distances from the shelf break. Body mass and size were positively associated with deep diving and negatively associated with long flights, suggesting morphology influences foraging and commuting efficiency. Murres from St. Paul (farther from the shelf break) were larger than those from St. George (nearer the shelf break), foraged exclusively in the middle shelf domain, made deep dives during daylight, and fed on larger benthic prey. In contrast, smaller murres from St. George commuted greater distances to beyond the shelf break, made shallow dives at night, and fed on smaller, high-energy, schooling, vertical-migrating prey. Both foraging strategies resulted in similar chick-feeding rates and fledging success. The largest and the smallest murres experienced less stress during breeding compared to intermediate-sized murres, suggesting divergent selection for body size between islands. Nesting murres, as central-place foragers, may experience strong selection pressure on body size and other adaptive traits that reflect differences between breeding colonies in foraging ecology and the acquisition of resources for reproduction.


KEY WORDS:  Body size · Foraging · Diving · Marine habitats · Stress levels · Bering Sea · Murres · Seabirds


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Cite this article as: Paredes R, Orben RA, Roby DD, Irons DB and others (2015) Foraging ecology during nesting influences body size in a pursuit-diving seabird. Mar Ecol Prog Ser 533:261-276. https://doi.org/10.3354/meps11388

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