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Marine Ecology Progress Series

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MEPS 352:269-274 (2007)  -  DOI:

Seabird behavior as an indicator of food supplies: sensitivity across the breeding season

Ann M. A. Harding1, John F. Piatt2,*, Joel A. Schmutz2

1Environmental Science Department, Alaska Pacific University, 4101 University Drive, Anchorage, Alaska 99508, USA
2US Geological Survey, Alaska Science Center, 1011 East Tudor Road, Anchorage, Alaska 99503, USA
*Corresponding author. Email:

ABSTRACT: We used empirical data on the time allocation of common murres Uria aalge in relation to measures of local prey density to examine whether adults provisioning chicks are more sensitive to changes in prey density than birds that are incubating eggs. We hypothesized that seasonal differences in food requirements of incubating and chick-rearing parents would affect the form of the relationship between time spent at the colony and local food density. We found that the relationship did differ between the incubation and chick-rearing period in 3 important ways: (1) there was a strong non-linear relationship between food density and colony attendance during chick-rearing and a weaker relationship during incubation; (2) incubating birds were able to maintain relatively constant rates of attendance over a wider range of food densities than chick-rearing birds and only reduced colony attendance under extremely poor feeding conditions, if at all; and (3) incubating birds spent more time attending nest sites at the colony than provisioning birds. These differences confirmed that chick-rearing parents are more sensitive to changes in food density than incubating parents, and that measurements of time allocation during the incubation period would have limited value as an indicator of ecosystem change.

KEY WORDS: Colony attendance · Prey density · Seabird · Uria aalge · Hydroacoustic surveys · Incubation · Provisioning · Chick-rearing

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Cite this article as: Harding AMA, Piatt JF, Schmutz JA (2007) Seabird behavior as an indicator of food supplies: sensitivity across the breeding season. Mar Ecol Prog Ser 352:269-274.

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