Alternative models of conspecific attraction in flies and crabs

Animals are often attracted to one another when selecting habitats, but little is known about the rules governing conspecific attraction. We use Akaike Information Criterion to evaluate alternative models of the effects of conspecifics on individual choice in the context of habitat selection. One set of models was tested using data collected on virgin female flies, Drosophila melanogaster, selecting habitats in the laboratory; a second set of models was tested using data collected on crabs, Ocypode rotundata, selecting foraging patches in the field. Patterns of space use in the flies were most consistent with models indicating that individuals were attracted to other females that selected traps during the same hour, as well as to cues left by females that had entered traps during the previous hour. Results for the crabs were most consistent with a model which assumes that individuals preferred to join the patch with the most crabs but that their ability to assess the number of crabs in alternative patches was constrained by basic psychophysical principles (Weber's law). These results provide support for hypotheses about the functional significance of conspecific attraction in the flies and the crabs and illustrate the richness of information about conspecific attraction that can be obtained when the same data set is confronted with alternative models of the ways that animals respond to one another when selecting habitats. Copyright 2005.