FERNANDEZ, M.J*; BOZINOVIC, F.B; Pontificia Universidad Catolica de Chile; Pontificia Universidad Catolica de Chile: Flight efficiency and energetic costs along an altitudinal gradient in the world’s largest hummingbird: Patagona gigas

Patagona gigas is an outlier in the body size distribution of the approximately 330 species of hummingbirds, weighing twice as much as the second largest one. Hovering flight has been described as the most energetically expensive form of locomotion, and is increasingly costly with increasing size. Its seasonal migrations, tracking the availability of floral nectar, take it from southern South America to the equator and from coastal regions to mountain regions of the Andes. Due to the lower barometric pressure of air at altitude, hovering flight becomes more difficult and hummingbirds must increase power production, yet the lower availability of oxygen may impose a physiological constraint on the metabolic power available for hovering flight. In this study we explore these potential mechanical and physiological constraints on hovering flight along an altitudinal gradient by measuring the power output (wing beat kinematic and morphometric parameters) and the power input (VO2 consumption during hovering flight) in order to estimate the flight efficiency .Coupling this information with behavioral studies examining the amount of time these hummingbirds performed various activities in the field to determine if P. gigas makes changes in its life-style at altitude that could be attributed to its extreme size.