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Exploration or exploitation: life expectancy changes the value of learning in foraging strategies


  • Sigrunn Eliassen,

  • Christian Jørgensen,

  • Marc Mangel,

  • Jarl Giske

S. Eliassen (, C. Jørgensen and J. Giske: Dept of Biology, Univ.y of Bergen, P. O. Box 7800, NO-5020 Bergen, Norway. – M. Mangel, Dept of Applied Mathematics and Statistics, Univ. of California Santa Cruz, CA 95064, USA.


The acquisition of information is a fundamental part of individual foraging behaviour in heterogeneous and changing environments. We examine how foragers may benefit from utilizing a simple learning rule to update estimates of temporal changes in resource levels. In the model, initial expectation of resource conditions and rate of replacing past information by new experiences are genetically inherited traits. Patch-time allocation differs between learners and foragers that use a fixed patch-leaving threshold throughout the foraging season. It also deviates from foragers that obtain information about the environment at no cost. At the start of a foraging season, learners sample the environment by frequent movements between patches, sacrificing current resource intake for information acquisition. This is done to obtain more precise and accurate estimates of resource levels, resulting in increased intake rates later in season. Risk of mortality may alter the trade-off between exploration and exploitation and thus change patch sampling effort. As lifetime expectancy decreases, learners invest less in information acquisition and show lower foraging performance when resource level changes through time.