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SEPG 2090 - Date Awarded 2002
Sex-specific foraging behaviour in tropical boobies: does size matter?
Sue Lewis
Abstract
Sexual differences in the foraging behaviour of parents have been observed in a number of sexually size dimorphic birds, particularly seabirds, and the usual inference has been that these sex-specific differences are mediated primarily by differences in body size. Alternatively these differences could be a consequence of sex rather than size. To examine whether size or sex drives sex differences in foraging behaviour, the foraging behaviour of parents was compared between two species of seabird, the brown booby which is highly sexually size dimorphic and the red-footed booby where sex differences in body size are much less marked. Using temperature and depth loggers, we found that there were significant differences in some aspect of the foraging behaviour of males and female boobies but not in others. Despite the tendency for red-footed boobies to show a sex difference in dive rate, all of the sex differences observed were only statistically significant in the brown boobies. Therefore using these data, we cannot reject the size hypothesis. However, this work highlights the need to investigate sexual differences in the foraging behaviour of seabirds and other species more closely, in order to test alternative theories that do not only rely on differences in body size.
Full report: SEPG2090
Publications:
S. Lewis, E.A. Schreiber, F. Daunt, G.A. Schenk, S. Wanless and K.C. Hamer. (2004) Flexible foraging patterns under different time constraints in tropical boobies. Animal Behaviour, 68, 1331-1337
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