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Type: Video
Host Agency:
  • US Forest Service, Missoula Fire Sciences Laboratory
Publication Date: October 18, 2012

This seminar is part of the USFS Missoula Fire Lab Seminar Series.

This webinar is a three-part sampler platter of research in the flight lab at the Field Research Station, each presentation will be ~12 min in length, with ~3 min for questions between presentations. The presenters include Bret Tobalske, Kristen Crandell, and Brett Klaassen from the University of Montana. 1) Tobalske, Power Output and Intermittent Flight: Flight is the most costly form of animal locomotion in terms of energy consumption per unit time (power). Unlike in terrestrial locomotion where power costs increase linearly with speed, flight costs vary according to a U-shaped curve as speed increases. We have measured in vivo work and power output in medium-sized and larger birds using surgically implanted strain gauges and sonommicrometry tranducers. The primary flight muscles of birds exhibit large strains (30-40%) to output work. Intermittent flight is one strategy to reduce average power costs. Flap-bounding, common in small birds, consists of flapping phases interspersed with flexed-wing bounds. It is an aerodynamically attractive strategy because birds can generate lift using just their body and tail. 2) Crandell, Unsteady Aerodynamics and the Function of Clap-and-Peel: Until recently, the aerodynamics of birds have been modeled using engineering principles associated with airplanes. However, complex wing motions suggest that unsteady aerodynamic mechanisms, time-dependent airflow around and about a wing, plays a large role. This is particularly true during slow, energetically costly flight. I will discuss various unsteady mechanisms and go in to detail on the 'clap and peel;' a mechanism many birds use to improve force production by 50% using a surprising technique similar to a squid. 3) Klaassen, Understanding the Wing Continuum: Birds face extreme selective pressures to stay aloft. Morphological adaptation to different aerial environments may seem intuitive at first glance, but exactly what makes one wing better than another in certain conditions is not well-known. For example, albatross and condors both spend a majority of their time soaring, but their wing shapes are markedly different. What environmental variables contribute to these morphological differences, and how do these varying morphologies affect aerodynamics? Through empirical wind tunnel studies, computational fluid dynamics, and particle image velocimetry of both living and dead animals, I hope to elucidate the mechanisms influencing morphological adaptation occurring at the wing-air-ecology interface. This short talk will introduce some of our preliminary findings, difficulties, and future directions.

Recording Length: 1:03:29
Online Link(s):
Link to this recording (390 MB; wmv)
Link to this recording (62 MB; mp4)

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  • avian aerodynamics
  • avian locomotion
  • avian wing motions
Record Last Modified:
Record Maintained By: FRAMES Staff (
FRAMES Record Number: 13978