Optimal foraging in bumblebees: Rule of movement between flowers within inflorescences

It is hypothesized that nectar-collecting bumblebees will be found to forage in ways that maximize their net rate of energy intake. Attention is focused, in this paper, on the manner in which these bumblebees move from one flower to another within inflorescences. Observations were made on workers of Bombus appositus, which were collecting nectar from Aconitum columbianum (monkshood). The rule of movement of the bumblebees was determined and compared, in terms of net rate of energy intake, with several possible alternative rules. Two of these alternatives gave equally high net rates of energy intake. The observed rule was very similar in nature to one of these and indistinguishable from both in terms of net rate of energy intake.