Mechanical power curve measured in the wake of pied flycatchers indicates modulation of parasite power across flight speeds.

ABSTRACT: How aerodynamic power required for animal flight varies with flight speed determines optimal speeds during foraging and migratory flight. Despite its relevance, aerodynamic power provides an elusive quantity to measure directly in animal flight. Here, we determine the aerodynamic power from wake velocity fields, measured using tomographical particle image velocimetry, of pied flycatchers flying freely in a wind tunnel. We find a shallow U-shaped power curve, which is flatter than expected by theory. Based on how the birds vary body angle with speed, we speculate that the shallow curve results from increased body drag coefficient and body frontal area at lower flight speeds. Including modulation of body drag in the model results in a more reasonable fit with data than the traditional model.

SUBMITTER: Johansson LC 

PROVIDER: S-EPMC5805985 | biostudies-literature | 2018 Jan

REPOSITORIES: biostudies-literature