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Sex-Specific Foraging Distributions of Brown Boobies in the Eastern Tropical Pacific

James D. Gilardi
Colonial Waterbirds
Vol. 15, No. 1 (1992), pp. 148-151
Published by: Waterbird Society
DOI: 10.2307/1521367
Stable URL: http://www.jstor.org/stable/1521367
Page Count: 4
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Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Sex-Specific Foraging Distributions of Brown Boobies in the Eastern Tropical Pacific
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Abstract

This study investigates sex differences in the distribution of foraging Brown Boobies (Sula leucogaster) near Clipperton Island in the eastern tropical Pacific. Females tended to forage farther from shore than males: eg., the sex ratio varied from strongly male-biased near the colony (within ∼20 km) to female-biased away from the colony (beyond ∼90 km). Males also returned to the colony earlier in the evening than females, again suggesting more proximate foraging locations in males. An hypothesis linking these foraging differences to sex role partitioning and sexual size dimorphism is proposed. Selection on females for increased chick provisioning may have lead to increased size and foraging range. Conversely, males are selected to remain close to the colony to maintain territories and prevent or acquire extra-pair copulations, thus reducing their foraging range and body size.

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