Animal Flight Laboratory

Research

Flight has been a significant underpinning to adaptive radiation in insects, birds, and bats. Moreover, wing flapping in both insects and volant vertebrates provides a general problem for biomechanical analysis in that neither maneuverability nor limits to flight performance are well understood. Equally unclear is the extent to which biomechanical capacity to fly is actually utilized in nature, either for extant taxa or for possible evolutionary intermediates. Our approach to these problems involves a variety of volant taxa and is two-fold in character: laboratory investigations of physiological and biomechanical constraints on flight performance, and fieldwork to elucidate the biomechanics of animal flight under natural circumstances. The overall goal of this research program is to elucidate both evolutionary origins and subsequent diversification of flight mechanisms, broadly construed.
Representative Research
1.Biomechanics and evolution of gliding flight in arthropods
Working in Peru and Panama, I and collaborators Steve Yanoviak and Mike Kaspari are investigating aerial behaviors and the biomechanical underpinnings to directed aerial descent in arboreal arthropods. We use a canopy walkway and climb rainforest trees to obtain a broad diversity of wingless taxa for study. Documentation of aerial behaviors in these groups has important implications for our understanding of the evolutionary origins of insect flight.

2. Animal flight performance across elevational gradients
Increasing elevation involves a substantial reduction in both air density and oxygen partial pressure, which in concert potentially compromise the ability of animals to fly. In Peru, I and collaborators Jim McGuire, Chris Witt, and Doug Altshuler are linking hemoglobin sequence variation to hematological parameters, whole-animal flight energetics, and hypoxia resistance, using hovering hummingbirds as a model system. In Sichuan, southwestern China, I and collaborator Michael Dillon are studying, both inter- and intraspecifically, the ability of bumblebees to hover across a 4000 meter elevational gradient.

3. Allometry of lift and power production in hovering insects and hummingbirds
The size-dependence of maximum performance in hovering animals remains quantitatively unresolved. Using a maximal load-lifting method of, I and collaborators Doug Altshuler (hummingbirds) and Michael Dillon (orchid bees) are evaluating interspecific variation in maximum lifting performance for approximately fifty hummingbird species and twelve orchid bee species. Prior interspecific comparisons of animal flight performance have violated statistical assumptions of independence of data points. We are implementing phylogenetically controlled interspecific analyses of maximum lifting performance, and are linking mechanistically the negative allometry of wingbeat frequency with geometrical constraints on stroke amplitude to evaluate changes in hovering capacity with body mass.

Current research projects

  • Elevational variation in flight mechanics and energetics of the giant hummingbird - M.Jose Fernandez
  • Relative contribution of morphology and behavior to mimicry in ithomiine butterflies - Ryan Hill