The distribution of unequal predators across food patches is not necessarily (semi)truncated

Game theoretical studies on contest behavior suggest that in foraging predators, interference through loss of foraging time is strongest between equal competitors. However, this phenomenon has not been incorporated into mechanistic models of interference. Instead, such models currently assume that individuals suffer most from dominant competitors, resulting in (semi)truncated, ideal free distributions (IFDs) of animals. Here, we develop a mechanistic interference model for 2 types of competitors: subordinates and dominants. The assumptions are that subordinates suffer interference through loss of foraging time from dominants but not vice versa. Time loss is greatest when 2 equal searchers interfere. A striking property of this 2-phenotype interference model is that dominants are most superior at intermediate values of the parameters prey density, handling time, and searching efficiency. This is because there the proportion of interfering subordinates relative to interfering dominants was highest. As the interference area for equal searchers increases, the difference in interference between dominants and subordinates diminishes. The IFD of the model is a mixed one with a larger share of dominants on the better patch but where the range of feeding rates exhibited by dominants and subordinates is the same for each patch. This contrasts with the (semi)truncated IFD predicted from other mechanistic interference models. We illustrate the generality of the model assumptions on interference and suggest that our modeling framework is applicable to many predator--prey systems. Copyright 2009, Oxford University Press.