Landmarks or Obstacles: The Effects of Spatial Heterogeneity on Bumble Bee Foraging Behavior

Abstract

Nectar-collecting bumble bees were followed on their foraging routes between plants of Hieracium aurantiacum and the effects of environmental heterogeneity on interplant flight distance and directionality were examined. In both natural environments and those in which landmarks (environmental features protruding above the herb layer) were removed, there was a significant inverse relationship between residence time per flowering head and distance of the next inter-plant flight made. However, bumble bees moved differently in areas containing landmarks versus uniform flower stands in two respects: 1) Inter-plant flight distances were significantly longer in uniform areas. 2) Significantly fewer backwards-oriented flights were made in uniform areas. Thus, bumble bees are likely to move more rapidly through uniform habitats than those with boundary or landmark features. Studies of optimal foraging behavior in pollinators, and gene flow in the plants that they service, should consider more comprehensively the range of habitats in which the organisms are found.