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Predator inadvertent social information use favours reduced clumping of its prey


  • Steven Hamblin,

  • Kimberley J. Mathot,

  • Julie Morand-Ferron,

  • Joseph J. Nocera,

  • Guillaume Rieucau,

  • Luc-Alain Giraldeau

S. Hamblin (, K. J. Mathot, J. Morand-Ferron, J. J. Nocera, G. Rieucau and L-A. Giraldeau, Groupe de recherche en écologie comportementale et animale, Dépt des Sciences Biologiques, Univ. du Québec à Montréal, C.P. 8888, Succursale Centre-ville, Montréal, QC, H3C 3P8, Canada. Present address for JJN: Ontario Ministry of Natural Resources, Trent Univ., DNA Building, 2140 East Bank Drive, Peterborough, ON, K9J 7B8, Canada.


When animals forage socially, individuals can obtain prey from their own searching (producer tactic) or by using the behaviour of others (scrounger tactic) when it provides inadvertent social information (ISI) that food has been located. This ISI may either indicate the location of food (social information, SI), or it may indicate the quality of the resource (public information, PI). To date, few studies have explored the selective consequences for prey of being exploited by predators that use ISI. Prey exploited by such predators should evolve traits that favour high levels of ISI use (scrounging) because this would result in lower predator search efficiency given that fewer predators would be searching directly for the prey. Our simulations confirm that ISI-using predators should increase their use of ISI when their prey form larger clumps resulting in higher prey survival. Our objective therefore is to explore whether prey will evolve towards higher clumpiness when their predators use ISI, using genetic algorithm simulation. The prey were subjected to one of three types of predators for over 500 prey generations. The predators either used: (1) no social information (NS), (2) SI only, or (3) PI. Surprisingly, the prey evolved the highest clumpiness for NS predators. Prey evolved towards smaller clump sizes with SI predators and the clumps were marginally larger when predators used PI. The result is due to the prey evolving the minimum clumpiness required to cause maximal ISI use by their predators. We discuss how this response by prey may favour the use of PI over SI in their ISI-using predators.