, Volume 90, Issue 5, pp 226–230 | Cite as

To see or not to see: does previewing a future opponent affect the contest behavior of green swordtail males (Xiphophorus helleri)?

  • Ryan L. Earley
  • Megan Tinsley
  • Lee Alan Dugatkin
Short Communication


Animals assess the fighting ability of conspecifics either by engaging in aggressive interactions or observing contests between others. However, whether individuals assess physical prowess outside the context of aggressive interactions remains unknown. We examined whether male green swordtails (Xiphophorus helleri) extract information about the fighting ability of solitary individuals via observation and whether acquiring such information elicits behavioral modifications. Contests preceded by mutual visual assessment were significantly shorter than fights where only one or neither of the two individuals was informed in advance. Focal animals initiated aggressive behavior more often against larger opponents only after previewing their adversary, indicating that swordtails can extract information about relative body size from watching solitary conspecifics. When a fighting disadvantage is perceived, observers adopt tactics that increase their probability of winning the contest.


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Copyright information

© Springer-Verlag 2003

Authors and Affiliations

  • Ryan L. Earley
    • 1
    • 3
  • Megan Tinsley
    • 2
  • Lee Alan Dugatkin
    • 1
  1. 1.Department of Biology, Life Sciences BuildingUniversity of LouisvilleLouisvilleUSA
  2. 2.Department of Ecology and Evolutionary BiologyUniversity of TennesseeKnoxvilleUSA
  3. 3.Department of BiologyGeorgia State UniversityAtlantaUSA

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