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Effect of sexual dimorphism in bill length on foraging behavior: an experimental analysis of hummingbirds

Oecologia volume 94, pages 87–94 (1993)Cite this article

Abstract

We examined whether sexual differences in trophic morphology are associated with sexual differences in foraging behavior through two laboratory experiments on rufous hummingbirds (Selasphorus rufus) designed to compare probing abilities (maximum extraction depths) and handling times of sexes at flowers. Bills of female S. rufus are about 10.5% longer than bills of males, and this difference was associated with sexual differences in foraging abilities. Maximum extraction depths of female S. rufus were significantly greater than those of males, and no overlap between the sexes was observed. Moreover, handling times of females were shorter than handling times of males at flowers having longer corollas (≥15 mm). Thus, because of their longer bills, female S. rufus have the potential to feed from longer flowers than males, and can do so more quickly. We suggest that no single mechanism is responsible for the evolution of sexual dimorphism in bill lengths of hummingbirds, but rather that the dimorphism probably reflects the combined effects of reproductive role division and intersexual food competition, and possibly, sexual selection.

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Author notes

  1. Ethan J. Temeles

    Present address: National Zoological Park, Smithsonian Institution, 20008, Washington, DC, USA

Authors and Affiliations

  1. Department of Zoology, University of British Columbia, V6T 1Z4, Vancouver, British Columbia, Canada

    Ethan J. Temeles & W. Mark Roberts

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  1. Ethan J. Temeles
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  2. W. Mark Roberts
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Temeles, E.J., Roberts, W.M. Effect of sexual dimorphism in bill length on foraging behavior: an experimental analysis of hummingbirds. Oecologia 94, 87–94 (1993). https://doi.org/10.1007/BF00317307

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  • DOI: https://doi.org/10.1007/BF00317307

Key words

  • Sexual dimorphism
  • Foraging behavior
  • Plant-pollinator interactions
  • Hummingbirds
  • Trochilidae