Habitat selection and population interactions: the search for mechanism

Competition within a single species forces the use of a wide variety of habitats. A second, competing species can reverse the effects of competition within a species, producing habitat selection where it would not otherwise exist. This effect is really a cluster of effects. Whether competition restores selectivity depends on the kind of competition at work and on the information-gathering abilities of foragers. So does the extent to which it is restored. Generally, the strongest separation of species by habitat selection results from distinct-preference competition between species whose individuals have very limited abilities to assess the density of food in a patch. But if individuals have much ability to assess food density, there is little or no increase likely in their selectivity compared with the single-species case. Habitat selection may stabilize predation as well as competition. The conditions required for stabilization closely resemble those predicted by optimal-foraging theory: victims need to prefer the safer habitat most when their populations are lowest or when their chance of being killed in the riskier habitat is highest. Multispecies studies emphasize the potential for differential susceptibility and optimal habitat selection to maintain diverse communities. -from Author