The Phenomenon
Young birds and other animals beg for food from their parents. It appears that in many species the intensity of begging varies with the need of the chick and that parents give more food to those chicks that beg more. Since parents respond differentially, chicks have an incentive to overstate their need since it will result in them receiving more food. If all chicks overstate their need, parents have an incentive to ignore the begging and give food using some other rule.
This situation represents a case of animal signaling where there arises an evolutionary question to explain the maintenance of the signal. The Sir Philip Sidney game formalizes a suggestion from Amotz Zahavi that reliability is maintained by making the signal costly to produce—chicks expend energy in begging. Since it requires energy to beg, only those chicks who are in dire need should be willing to expend the energy to secure food.
Read more about this topic: Sir Philip Sidney Game
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