Variable predators and switching behavior

Models are developed in which prey preferences vary between individual predators but the preference of an individual does not change with prey relative density. These two properties generally lead to the surprising conclusion that the aggregate preference of a population of predators does change with prey relative density. This phenomenon may result in negative or positive switching, depending on the circumstances, with negative switching being the more likely result. Such population negative switching is found in previously published experimental data. Implications are given for the analysis of ecological data, and some implications for the stability of field populations are suggested.