Foraging ecology during nesting influences body size in a pursuit-diving seabird
|Author(s)||Paredes Rosana1, Orben Rachael A.2, Roby Daniel D.3, Irons David B.4, Young Rebecca5, Renner Heather6, Tremblay Yann7, Will Alexis5, Harding Ann M. A.8, Kitaysky Alexander S.5|
|Affiliation(s)||1 : Oregon State Univ, Dept Fisheries & Wildlife, Corvallis, OR 97331 USA.
2 : Univ Calif Santa Cruz, Long Marine Lab, Ocean Sci Dept, Santa Cruz, CA 95060 USA.
3 : Oregon State Univ, US Geol Survey, Oregon Cooperat Fish & Wildlife Res Unit, Corvallis, OR 97331 USA.
4 : US Fish & Wildlife Serv, Anchorage, AK 99503 USA.
5 : Univ Alaska Fairbanks, Inst Arctic Biol, Fairbanks, AK 99775 USA.
6 : US Fish & Wildlife Serv, Alaska Maritime Natl Wildlife Refuge, Homer, AK 99603 USA.
7 : IRD, Marine Biodivers Exploitat & Conservat, MARBEC UMR248, F-34203 Sete, France.
8 : Alaska Pacific Univ, Environm Sci Dept, Anchorage, AK 99508 USA.
|Source||Marine Ecology Progress Series (0171-8630) (Inter-research), 2015-08 , Vol. 533 , P. 261-276|
|WOS© Times Cited||10|
|Keyword(s)||Body size, Foraging, Diving, Marine habitats, Stress levels, Bering Sea, Murres, Seabirds|
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.