Social Foraging by Honey Bees: Mechanisms, Dynamics, and Adaptation

There are two main components of social foraging by honey bees. First, there is a continuous adjustment of the number of bees dedicated to exploitation of forage sites and wide-area exploration for new forage options. Second, there is a persistent reallocation of the proportions of the foraging workforce dedicated to exploiting each site in order to match unpredictably changing relative forage site profitabilities. In this paper we develop a model of bees’ foraging for nectar that can represent individual-level sensing, decision-making, and communication mechanisms, along with known restrictions on information flow in the hive. Our model also represents that as additional bees forage at a site its profitability generally degrades due to exploitation competition; hence, we can study the intimate coupling between the dynamics of forage site profitability and the hive’s reallocation of foragers. To illustrate these dynamics, we first show how in spite of the fact that no bee can know the profitability of all sites, the hive achieves an approximate “ideal free distribution” (IFD) of foragers with an allocation of foragers proportional to relative site profitability. We identify the mechanisms underlying the achievement of the emergent distribution and the hive’s ability to completely ignore forage sites of relatively inferior quality. We explain how the mechanisms lead to fast reallocations when there are sudden and significant site profitability changes or new site discoveries. Next, we show that natural selection seems to have settled on values of the behavioral parameters representing the dance strength determination rule that balance the desire to maximize nectar intake, yet minimize the time-energy investments in dancing. We show that achievement of this balance allows for individual-level forage site profitability assessment errors since the foraging process effectively filters such errors at the colony level. Finally, we identify the close relationships between the dynamics of social foraging and nest-site selection by honey bees since it provides an excellent example of how changing a single individual-level behavioral rule can result in dramatically different emergent group behavior. Building on these relationships we briefly discuss how social foraging can be viewed as a group cognition process.