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Carrying capacity models should not use fixed prey density thresholds: a plea for using more tools of behavioural ecology


  • Jan A. Van Gils,

  • Pim Edelaar,

  • Graciela Escudero,

  • Theunis Piersma

Jan A. van Gils, Pim Edelaar, Graciela Escudero and Theunis Piersma, Royal Netherlands Inst. for Sea Research (NIOZ), P.O. Box 59, NL-1790 AB Den Burg, The Netherlands, and Centre for Ecological and Evolutionary Studies, Univ. of Groningen, P.O. Box 14, NL-9750 AA Haren, the Netherlands (


Earlier studies have developed models of carrying capacity to predict the number of animals a certain area can support. These models assume that resources are not renewed after consumption (‘standing stock’ models), and that the initial number of prey and the rate of prey consumption determine the time a population of foragers can live in an area. Within such areas, foragers give up feeding at a sub-site or patch when intake rates no longer cover energy expenditure. To improve the success rate of the models’ predictions, we here change the existing rate-maximising models into fitness-maximising models, and include dynamics in the availability of patches. These new (conceptual) models show that the approaches used so far may over- as well as underestimate carrying capacity. We review empirical studies that have aimed to estimate carrying capacity, and discuss how concepts have been confused. We make explicit suggestions on how to proceed in predicting carrying capacities in future studies.