Cats protecting birds: modelling the mesopredator release effect

1. Introduced predators account for a large part of the extinction of endem ic insular species, which constitutes a major component of the loss of biod iversity among vertebrates. Eradication of alien predators from these ecosy stems is often considered the best solution. 2. In some ecosystems, however, it can generate a greater threat for endemi c prey through what is called the 'mesopredator release'. This process pred icts 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 modal, wi th 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 in troduced superpredators, such as feral domestic cats, is not always the bes t solution to protect endemic prey when introduced mesopredators, such as r ats, are also present.