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Marine Ecology Progress Series

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MEPS 352:245-258 (2007)  -  DOI:

Stress hormones link food availability and population processes in seabirds

A. S. Kitaysky1,*, J. F. Piatt2, J. C. Wingfield3

1Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, Alaska 99775, USA
2USGS Alaska Science Center, 1011 East Tudor Road, Anchorage, Alaska 99503, USA
3Department of Biology, University of Washington, Seattle, Washington 98195, USA

ABSTRACT: Catastrophic population declines in marine top predators in the northern Pacific have been hypothesized to result from nutritional stress affecting reproduction and survival of individuals. However, empirical evidence for food-related stress in wild animals is frequently lacking or inconclusive. We used a field endocrinology approach to measure stress, identify its causes, and examine a link between stress and population processes in the common murre Uria aalge. We tested the empirical relationship between variations in the stress hormone corticosterone (CORT) and food abundance, reproduction, and persistence of individuals at declining and increasing colonies in Cook Inlet, Alaska, from 1996 to 2001. We found that CORT secretion in murres is independent of colony, reproductive stage effects, and gender of individuals, but is directly negatively correlated with abundance of their food. Baseline CORT reflected current food abundance, whereas acute stress-induced CORT reflected food abundance in the previous month. As food supply diminished, increased CORT secretion predicted a decrease in reproductive performance. At a declining colony, increased baseline levels of CORT during reproduction predicted disappearance of individuals from the population. Persistence of individuals in a growing colony was independent of CORT during reproduction. The obtained results support the hypothesis that nutritional stress during reproduction affects reproduction and survival in seabirds. This study provides the first unequivocal evidence for CORT secretion as a mechanistic link between fluctuations in food abundance and population processes in seabirds.

KEY WORDS: Corticosterone · Food availability · Stress · Seabirds · Population processes

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Cite this article as: Kitaysky AS, Piatt JF, Wingfield JC (2007) Stress hormones link food availability and population processes in seabirds. Mar Ecol Prog Ser 352:245-258.

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