Journal of Comparative Physiology A

, Volume 165, Issue 4, pp 573–576 | Cite as

Stationary underwater prey missed by reef herons,Egretta gularis: head position and light refraction at the moment of strike

  • Gadi Katzir
  • Arnon Lotem
  • Nathan Intrator


This paper attempts to verify the importance of spatial positioning of the eyes of reef heronsEgretta gularis schistacea, when coping with light refraction at the air-water interface. The herons' striking of prey, while their approach angle was restricted, was observed. (a) The herons' capture success in the restricted situation was markedly lower than in the unrestricted situation. (b) The points of strike (STR) in unsuccessful strikes differed from those of successful strikes, and from those of the unrestricted situation. (c) The larger the difference between the observed and the predicted ratio of prey depth to apparent prey depth, the higher the probability of missing a prey. These results support predictions of a model presented elsewhere (Katzir and Intrator 1987) that a heron will attempt to reach spatial positions at which prey's real depth and apparent depth are linearly correlated.


Refraction Spatial Position Head Position Capture Success Apparent Depth 
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Copyright information

© Springer-Verlag 1989

Authors and Affiliations

  • Gadi Katzir
    • 1
  • Arnon Lotem
    • 1
  • Nathan Intrator
    • 2
  1. 1.Department of ZoologyTel-Aviv UniversityTel-AvivIsrael
  2. 2.Department of Applied MathematicsBrown UniversityProvidenceUSA

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