Competition versus cooperation: success of individuals foraging alone and in groups.

Using a variant of information-sharing models, we examine the pros and cons of group foraging against the alternative of staying alone. Models of this category-assuming that in groups food finding by one results in food sharing by many-conclude that patch-finding rate improves with group size. In our modification interference among individuals reduces pooled searching efficiency of the group. We introduce a term, s, the probability of an individual's being among the ones sharing the food in a patch found by the group. Not unexpectedly, these fine-tunings prolong food-finding rates that push individuals in the group toward the foraging status of a solitary individual. With phenotype-related differences in s, foraging in groups turns out to be a less profitable option the lower an individual is ranked in the group. The model suggests that, in terms of food finding, individuals have to pay attention to their performance in the foraging group. The option of foraging alone may easily be a better strategy than that of a low-ranking individual foraging in a group. If so, the model also suggests groups assorted by phenotype.