honey storage levels by honey bees,

Honey bees collect distinct nutrient sources in the form of nectar (energy) and pollen (nitrogen). We investigated the effect of varying energy stores on nectar and pollen foraging. We found no significant changes in nectar foraging in response to changes in honey storage levels within colonies. Individual foragers did not vary activity rates or nectar load sizes in response to changes in honey stores, and colonies did not increase nectar intake rates when honey stores within the hive were decreased. This result contrasts with pollen foraging behavior, which is extremely sensitive to colony state. Our data show that individual foraging decisions during nectar collection and colony regulation of nectar intake are distincdy different from pollen foraging. The behavior of honey bees illustrates that foraging strategy (and therefore foraging models) can incorporate multiple curren-cies, including botJi energy and protein intake. Key words: foraging theory, honey bees, nectar foraging. [Behav Ecol 7:286-291 (1996)] The nutritional requirements of an animal (for example,energy and nitrogen) can vary independendy; thus we might expect that individual foragers have different decision rules to govern collection of different nutrients. However, in most animal systems it is difficult to separate die decision rules for different resources. In honey bees (Apis mellifera), energy and nitrogen requirements are met by two distinct resources