Spitting at the dinner table: archerfish (Toxotes chatareus) kleptoparasitism and social foraging

Juvenile archerfish forage in small groups by spitting down overhanging insects and by kleptoparasitizing prey downed by others. To explore factors affecting the use and success of kleptoparasitism, countermeasures, and tactics within a producer-scrounger framework, ten archerfish (Toxotes chatareus) were presented in groups of three, five, and seven with crickets of varying sizes and heights. Matching observations across taxa, kleptoparasitism increased with increasing group size, prey size, and handling time. Although some predictions of producer-scrounger theory were met (tactic preference and tactic use reflecting tactic success), the assumption of negative frequency dependent kleptoparasitism success was not, and the theory did not account for important factors found to affect tactic economics, including positioning, non-autonomous “producing”, and a frequency dependent “finder’s share”. This study confirms universal factors affecting kleptoparasitism and illustrates the difficulty of applying general theory to unique and complex systems. Suggestions for improving future social foraging studies are discussed.