In this lecture, we introduce social foraging as an opportunity for exploitation by conspecifics to either: (a) exploit positive externalities from the foraging behaviors of others, or (b) make foraging choices that reduce the benefit to others around them (imposing negative externalities). We discuss how these pressures complicate understanding the foraging group sizes observed in nature – such as densities of socially foraging bats and sizes of wolf packs. In particular, we introduce the tragedy of the commons (and open-access/common-pool resources) as a conceptual framework for understanding group sizes. We then pivot to focusing on within a group, how do individuals decide whether they should search for food or pay attention to others who are searching for food (and then parasitize the discovered food locations). This gives us an opportunity to use basic game theory to make predictions about behaviorally stable strategies (i.e., strategies that can change dynamically but will have consistent outputs in consistent contexts).
Topic highlights:
- positive and negative externalities in social foraging
- open-access/common-pool resources and the tragedy of the commons
- optimal group size and equilibrium group size
- producer–scrounger game
- Stable Equilibrium Frequency (SEF) and Behaviorally Stable Strategy (BSS)
Important terms: positive externality, negative externality, open-access resource/common-pool resource, tragedy of the commons, “G star” (intake-maximizing group size), “G hat” (open-access equilibrium group size), finder’s advantage, Stable Equilibrium Frequency (SEF), Behaviorally Stable Strategy (BSS)
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