Women from Venus, men from Mars: inter-sex foraging differences in the imperial cormorant Phalacrocorax atriceps a colonial seabird
Colonial seabirds are central place foragers and likely to be subject to substantial competition for resources. Mechanisms proposed for reducing intra-specific competition include differential inter-sex area use mediated by adult choice. We used GPS loggers and dive recorders to study area use and d...
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Published in | Oikos Vol. 120; no. 3; pp. 350 - 358 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
Oxford, UK
Blackwell Publishing Ltd
01.03.2011
Blackwell Publishers Blackwell |
Subjects | |
Online Access | Get full text |
ISSN | 0030-1299 1600-0706 1600-0706 |
DOI | 10.1111/j.1600-0706.2010.18387.x |
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Summary: | Colonial seabirds are central place foragers and likely to be subject to substantial competition for resources. Mechanisms proposed for reducing intra-specific competition include differential inter-sex area use mediated by adult choice. We used GPS loggers and dive recorders to study area use and dive depth in a total of 27 male and 26 female imperial cormorants Phalacrocorax atriceps breeding at a colony of some 6500 birds at Punta Leon, Chubut, Argentina during 2004 and 2005. Although time spent travelling and distances between the colony and foraging sites were similar for both sexes, males and females travelled away from their colony using routes virtually perpendicular to each other so that their foraging areas were distinctly different; females hunted close to the coast while males foraged offshore in deeper water. Consideration of foraging efficiency underwater, defined as the duration spent on the bottom divided by the dive cycle duration, showed that females were more efficient at depths < 40 m while males more efficient at depths > 40 m. We suggest that the substantial sexual dimorphism in this species may be responsible for the different depth-linked foraging efficiencies and that selection for appropriate depths could lead to differential habitat use and putative differences in prey selection. |
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Bibliography: | http://dx.doi.org/10.1111/j.1600-0706.2010.18387.x ark:/67375/WNG-V97CKM47-8 ArticleID:OIK18387 istex:DB6BA5FAEF76D3F47ACA64D0CDA3A05371D64863 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 14 ObjectType-Article-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0030-1299 1600-0706 1600-0706 |
DOI: | 10.1111/j.1600-0706.2010.18387.x |