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Marine Ecology Progress Series

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MEPS 432:277-290 (2011)  -  DOI:

Foraging effort does not influence body condition and stress level in little auks

Dariusz Jakubas1,*, Marta Głuchowska2, Katarzyna Wojczulanis-Jakubas1, Nina J. Karnovsky3, Liliana Keslinka1, Dorota Kidawa1, Wojciech Walkusz2,4, Rafał Boehnke2, Małgorzata Cisek2, Sławomir Kwaśiewski2, Lech Stempniewicz1

1University of Gdańsk, Department of Vertebrate Ecology and Zoology, Legionów 9, 80-441 Gdańsk, Poland
2Institute of Oceanology, Polish Academy of Sciences, Powsta΄nców Warszawy 55, 81-712 Sopot, Poland
3Pomona College, Department of Biology, 175 W. 6th St., Claremont, California 91711, USA
4Department of Fisheries and Oceans, 501 University Crescent, Winnipeg, Manitoba R3T 2N6, Canada

ABSTRACT: In conditions of deteriorating food availability, seabirds may maximize their breeding success by increasing reproductive effort, which compromises body condition, stress level, survival, and future reproductive success. We studied a small planktivorous alcid, the little auk Alle alle, in 2 breeding colonies in west Spitsbergen, Norway (Hornsund and Magdalenefjorden) with contrasting oceanographic conditions (Arctic and Atlantic environments, respectively). We hypothesized that the chick diet composition and parental foraging effort differs between these colonies, which results in intercolony variation in body mass and stress level of both adults and chicks. We found differences in sea temperature and salinity (both lower in Hornsund) and the abundance of Atlantic copepod Calanus finmarchicus (3.6 times less abundant in Hornsund) between foraging areas. Birds from both colonies foraged selectively on Calanus glacialis CV. Composition, total biomass and energy content of food loads were similar in both colonies, though food delivered to nestlings in Magdalenefjorden was more diverse. The frequency of feeds was also similar in both colonies. Parent little auks in ­Magdalenefjorden, however, performed longer foraging trips than in Hornsund (medians 183 vs. 124 min). Longer foraging trips suggest that these birds traveled longer distances to find abundant prey at the marginal sea ice zone and/or spent more time foraging close to the colony but in poorer foraging areas. Despite increased parental efforts in Magdalenefjorden, body mass and stress levels of adults and chicks were similar in both colonies. This suggests that little auks from northwest Spitsbergen did not reach a threshold requiring prioritization of self-maintenance over chick provisioning.

KEY WORDS: Little auk · Diet composition · Parental efforts · Body mass · Stress level

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Cite this article as: Jakubas D, Głuchowska M, Wojczulanis-Jakubas K, Karnovsky NJ and others (2011) Foraging effort does not influence body condition and stress level in little auks. Mar Ecol Prog Ser 432:277-290.

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