P1.72 Wednesday, Jan. 4 Flying high: body size, flight performance, and vertical stratification of orchid bee communities in tropical rainforests CRALL, J.D.*; COMBES, S.A.; Harvard University; Harvard University email@example.com
Forests are complex three-dimensional environments, characterized by significant gradients of wind speed and turbulence from the forest floor to the canopy. Such complexity is frequently accompanied by vertical stratification of animal communities. In this study, we collected orchid bees (Apidae: Euglossini) using scent-baiting at various heights in lowland tropical rainforests to investigate patterns of vertical stratification in relation to body size and flight performance. Orchid bee communities appear to be vertically differentiated, with larger-bodied species mostly absent from the upper canopy. Previous work has shown that, while energetically costly, extension of the hind legs improves flight stability of orchid bees in turbulent air by increasing moment of inertia and decreasing rolling moments. In contrast to expectations from isometric scaling, however, the contribution of leg extension to moment of inertia scales negatively with body size, indicating that smaller bees may be relatively more stable in turbulent air than larger bees. This increased stability, along with size-related differences in flight energetics, could help explain patterns of vertical stratification in relation to body size. Overall, our results imply that microhabitat use by flying insects is determined at least in part by flight performance and body size, which has important implications for forest structure and ecology.