Pollinator Foraging Strategies in Mixed Floral Arrays: Density Effects and Floral Constancy

The profitability of any foraging strategy may be in part dependent on the number of foragers adopting it, and so it can be viewed mathematically as a "game." We explore here the implications of a game-theoretic model of pollinators foraging on a mixed array of two flower species, with individual pollinators either specializing on one or the other, or else acting as generalists. We further allow for the possibility of specialist advantages in foraging efficiency. The predicted mixture of pollinator behavioral strategies depends on the overall floral density and the relative densities of the two flower species. Where floral resources are scarce, pollinators should behave as generalists whereas when resources are superabundant, specialization on the single most profitable flower type (all else being equal, the commonest one) is favored. At intermediate floral densities, a mix of floral specializations (floral constancy) is favored, so long as the rarer flower's density does not fall below some critical minimum level. Where the rarer flower is too rare, a mixture of generalists and common-species specialists is favored. Rare flowers are at a reproductive disadvantage in all cases, but their relative success is highest where their pollinators are flower constant.