The hidden cost of information in collective foraging.
Many animals nest or roost colonially. At the start of a potential foraging period, they may set out independently or await information from returning foragers. When should such individuals act independently and when should they wait for information? In a social insect colony, for example, information transfer may greatly increase a recruit's probability of finding food, and it is commonly assumed that this will always increase the colony's net energy gain. We test this assumption with a mathematical model. Energy gain by a colony is a function both of the probability of finding food sources and of the duration of their availability. A key factor is the ratio of pro-active foragers to re-active foragers. When leaving the nest, pro-active foragers search for food independently, whereas re-active foragers rely on information from successful foragers to find food. Under certain conditions, the optimum strategy is totally independent (pro-active) foraging because potentially valuable information that re-active foragers may gain from successful foragers is not worth waiting for. This counter-intuitive outcome is remarkably robust over a wide range of parameters. It occurs because food sources are only available for a limited period. Our study emphasizes the importance of time constraints and the analysis of dynamics, not just steady states, to understand social insect foraging.
Dechaume-Moncharmont
François-Xavier
FX
Centre for Behavioural Biology, School of Biological Sciences, University of Bristol, Woodland Road, Bristol BS8 1UG, UK. fx.dechaume@bristol.ac.uk
Dornhaus
Anna
A
Houston
Alasdair I
AI
McNamara
John M
JM
Collins
Edmund J
EJ
Franks
Nigel R
NR
D000819:Animal Communication; D000818:Animals; D003198:Computer Simulation; D005247:Feeding Behavior / Q000502:physiology*; D033181:Information Dissemination; D007313:Insecta / Q000502:physiology*; D008962:Models, Theoretical; D012919:Social Behavior; D013997:Time Factors