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Are age-related variations in breeding performance greatest when food availability is limited?

Published online by Cambridge University Press:  18 May 2005

A. Bunce
Affiliation:
Department of Zoology, University of Melbourne, Victoria 3010, Australia School of Ecology and Environment, Deakin University, 221 Burwood Highway, Burwood, Victoria 3125, Australia
S. J. Ward
Affiliation:
Department of Zoology, University of Melbourne, Victoria 3010, Australia
F. I. Norman
Affiliation:
Arthur Rylah Institute for Environmental Research, Department of Sustainability and Environment, P.O. Box 137, Heidelberg, Victoria 3084, Australia
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Abstract

Age-related improvements in reproductive performance in seabirds have been well documented, and may be explained by improvements in foraging efficiency or increased experience and reproductive effort with age. The interactive effects of parental age and food supply on reproductive performance, however, remain poorly understood. A widespread mass mortality of pilchards Sardinops sagax in southern Australian waters in 1998 provided a unique opportunity to investigate the effects of a sudden reduction in the availability of amajor prey species on Australasian gannets Morus serrator, an important local marine predator. Age-related differences in the breeding performance of gannets were evident in 1 year of reduced pilchard availability; when food was not limited, both young and experienced parents were equally capable of rearing chicks and had similar levels of breeding success. These data clearly demonstrate the interactive effects of parental age and food supply on breeding performance and suggest that such differences only become apparent when conditions become more stressful.

Type
Research Article
Copyright
2005 The Zoological Society of London

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