‘Take-away’ foraging spatially uncouples predator and prey-attack distributions

Authors

  • Isabel M. Smallegange,

    Corresponding author
    1. Royal Netherlands Institute for Sea Research (NIOZ), Department of Marine Ecology and Evolution, P.O. Box 59, 1790 AB, Den Burg (Texel), The Netherlands
      Correspondence author. E-mail: i.smallegange@imperial.ac.uk
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    • Present address: Division of Biology, Imperial College London, Silwood Park, Ascot, SL5 7PY, UK.

  • Jaap Van Der Meer,

    1. Royal Netherlands Institute for Sea Research (NIOZ), Department of Marine Ecology and Evolution, P.O. Box 59, 1790 AB, Den Burg (Texel), The Netherlands
    2. Free University, Institute of Ecological Science, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands
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  • Maurice W. Sabelis

    1. Institute for Biodiversity and Ecosystem Dynamics, Section Population Biology, P.O. Box 94084, 1090 GB, Amsterdam, The Netherlands
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Correspondence author. E-mail: i.smallegange@imperial.ac.uk

Summary

1. Ideal-free distribution theory assumes that in a patchy environment foragers maximize fitness and hence their feeding rate by balancing gains from more food against losses from more competition. Ultimately, individuals cannot increase their feeding rate by moving to another patch and they distribute themselves over patches in proportion to prey density per patch.

2. In our experiments with shore crabs Carcinus maenas foraging on two adjacent patches with mussels Mytilus edulis, the implicit assumption of ideal-free distribution theory that catch should match time spent in a prey patch is not met, however. Despite aggregating their attack where it is most profitable shore crabs distributed themselves homogeneously across mussel patches: they ‘take away’ the prey caught and consume it elsewhere to reduce interference.

3. Thus, predator distributions can be quite different from prey-attack distributions. This is important because the latter is shown to be decisive for persistence of predator and prey populations in ecological models.

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