Daily patterns of optimal producer and scrounger use under predation hazard: A state-dependent dynamic game analysis

Feeding in groups often gives rise to joining: feeding From other's discove ries. The joining decision has been modeled as a producer-scrounger game wh ere the producer strategy consists of searching for one's food and the scro unger strategy consists of searching for food discovered by others. Previou s models revealed that the evolutionarily stable proportion of scrounging m ostly depends on the fraction of each food patch available only to its prod ucer. These early models are static and state independent and are therefore unable to explore whether the time of day, the animal's state, and the deg ree of predation hazard influence an individual's decision of whether to us e the producer or scrounger strategy. To investigate these issues, we devel oped a state-dependent dynamic producer-scrounger game model. The model pre dicts that, early in the day, low reserves promote a preference for the scr ounger strategy, while the same condition late in the day favors the use of the producer strategy. Under rich and clumped food, the availability of sc rounging can improve the daily survival of any average group member. The mo del suggests only weak effects of predation hazard on the use of scrounging . Future developments should consider the effects of dominance asymmetries and allowing foragers a choice between foraging alone or in a group harbori ng an evolutionarily stable Frequency of scrounger.