Ashmole's halo: direct evidence for prey depletion by a seabird

Fish population densities were measured at various distances from 2 large colonies of double-crested cormorants Phalacrocorax auritus to test the hypothesis that seabirds deplete prey close to their colonies. Fish densities were significantly lower in bays used by cormorants for feeding than in thos...

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Bibliographic Details
Published in:Marine ecology. Progress series (Halstenbek) 1987-01, Vol.40 (3), p.205-208
Main Authors: Birt, V. L., Birt, T. P., Goulet, D., Cairns, D. K., Montevecchi, W. A.
Format: Article
Language:English
Subjects:
Bird nesting
Breeding
Ecological competition
Fish
Food supply
Foraging
Insect colonies
Marine
Marine fishes
Phalacrocorax auritus
Pisces
Reproductive success
Sea birds
Teleostei
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Summary:Fish population densities were measured at various distances from 2 large colonies of double-crested cormorants Phalacrocorax auritus to test the hypothesis that seabirds deplete prey close to their colonies. Fish densities were significantly lower in bays used by cormorants for feeding than in those outside their foraging range. Our findings provide direct evidence for prey depletion, and support Ashmole's (1963) hypothesis that seabird populations are limited by food supplies during the breeding season.
ISSN:0171-8630
1616-1599
DOI:10.3354/meps040205