QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online October 7, 2004
Journal of Experimental Biology 207, 3969-3976 (2004)
Published by The Company of Biologists 2004
doi: 10.1242/jeb.01234

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Hambly, C. Articles by Speakman, J. R. Search for Related Content PubMed PubMed Citation Articles by Hambly, C. Articles by Speakman, J. R. Social Bookmarking                         What's this?

The energy cost of loaded flight is substantially lower than expected due to alterations in flight kinematics

C. Hambly^1,*, E. J. Harper² and J. R. Speakman^1,3

¹ Aberdeen Centre for Energy Regulation and Obesity, School of Biological Sciences, University of Aberdeen, Aberdeen AB24 2TZ, Scotland, UK
² The Waltham Centre for Pet Nutrition, Waltham-on-the-Wolds, Leicestershire, LE14 4RT, England, UK
³ Aberdeen Centre for Energy Regulation and Obesity, Division of Energy Balance and Obesity, Rowett Research Institute, Bucksburn, Aberdeen AB21 9BS, Scotland, UK

^* Author for correspondence (e-mail: c.hambly{at}rowett.ac.uk)

Accepted 10 August 2004

The effect of experimentally increased wing loading on the energy cost of flight was examined in cockatiels Nyphicus hollandicus. Five individuals were flown for periods of approximately 2 min, while carrying additional payload mass amounting to between 5 and 20% of unloaded body mass. The energy cost of flight was measured using the ¹³C-labelled bicarbonate technique, which was also calibrated in a separate experiment on resting birds, by comparing the elimination rate of ¹³C in breath with a simultaneous measurement of oxygen consumption by indirect calorimetry. It was not possible to perform a similar calibration during flight when energy costs were higher, so we extrapolated the relationship from the resting calibration to predict flight cost. Flight cost in the pre-manipulated individuals averaged 16.7±1.8 W. Flight cost in the pre-manipulated birds was significantly related to the interaction between downstroke duration and flight speed. There was no significant increase in flight cost with increases in payload mass. The birds responded to payload masses between 5 and 15% of their unloaded body mass by decreasing flight speed relative to unloaded birds, while maintaining wing beat frequency (F_b). At a payload mass equivalent to 20% of body mass, however, the birds flew at higher speeds than unloaded controls, and had a significantly higher F_b, generated by a reduction in both the upstroke and downstroke durations. Wing amplitude was unaffected by the increase in loading. Using the measured flight parameters, the effect of loading was not significantly different than predicted using aerodynamic models.

Key words: cockatiel, Nyphicus hollandicus, flight cost, wing loading, labelled bicarbonate, kinematics

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?

This article has been cited by other articles:

				K. Sato, F. Daunt, Y. Watanuki, A. Takahashi, and S. Wanless A new method to quantify prey acquisition in diving seabirds using wing stroke frequency J. Exp. Biol., January 1, 2008; 211(1): 58 - 65. [Abstract] [Full Text] [PDF]