The effects of animal personality on the ideal free distribution.

The ideal free distribution (IFD) has been used to predict the distribution of foraging animals in a wide variety of systems. However, its predictions do not always match observed distributions of foraging animals. Instead, we often observe that there are more consumers than predicted in low-quality patches and fewer consumers than predicted in high-quality patches (i.e. undermatching). We examine the possibility that animal personality is one explanation for this undermatching. We first conducted a literature search to determine how commonly studies document the personality distribution of populations. Second, we created a simple individual-based model to conceptually demonstrate why knowing the distribution of personalities is important for studies of populations of foragers in context of the IFD. Third, we present a specific example where we calculate the added time to reach the IFD for a population of mud crabs that has a considerable number of individuals with relatively inactive personalities. We suggest that animal personality, particularly the prevalence of inactive personality types, may inhibit the ability of a population to track changes in habitat quality, therefore leading to undermatching of the IFD. This may weaken the IFD as a predictive model moving forward.