Cats protecting birds: modelling the mesopredator release effect

Authors

  • Franck Courchamp,

    1. Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Drive – La Jolla, CA 92093–0202, USA; and
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  • Michel Langlais,

    1. ERS CNRS 123 ‘Mathématiques Appliquées de Bordeaux’, Université Victor Segalen Bordeaux 2, 146 rue Léo Saignat, F-33076 Bordeaux Cédex, France
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  • George Sugihara

    1. Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Drive – La Jolla, CA 92093–0202, USA; and
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Franck Courchamp, Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, UK. E-mail fc219@cam.ac.uk. Tel: 01223-336643. Fax: 01223-336676.

Abstract

1. Introduced predators account for a large part of the extinction of endemic insular species, which constitutes a major component of the loss of biodiversity among vertebrates. Eradication of alien predators from these ecosystems is often considered the best solution.

2. In some ecosystems, however, it can generate a greater threat for endemic prey through what is called the ‘mesopredator release’. This process predicts that, once superpredators are suppressed, a burst of mesopredators may follow which leads their shared prey to extinction.

3. This process is studied through a mathematical model describing a three species system (prey–mesopredator–superpredator). Analysis of the model, with and without control of meso- and superpredators, shows that this process does indeed exist and can drive shared prey to rapid extinction.

4. This work emphasizes that, although counter-intuitive, eradication of introduced superpredators, such as feral domestic cats, is not always the best solution to protect endemic prey when introduced mesopredators, such as rats, are also present.

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