Power and metabolic scope of bird flight: a phylogenetic analysis of biomechanical predictions.
For flying animals aerodynamic theory predicts that mechanical power required to fly scales as P proportional, variant m (7/6) in a series of isometric birds, and that the flight metabolic scope (P/BMR; BMR is basal metabolic rate) scales as P (scope) proportional, variant m (5/12). I tested these predictions by using phylogenetic independent contrasts from a set of 20 bird species, where flight metabolic rate was measured during laboratory conditions (mainly in wind tunnels). The body mass scaling exponent for P was 0.90, significantly lower than the predicted 7/6. This is partially due to the fact that real birds show an allometric scaling of wing span, which reduces flight cost. P (scope) was estimated using direct measurements of BMR in combination with allometric equations. The body mass scaling of P (scope) ranged between 0.31 and 0.51 for three data sets, respectively, and none differed significantly from the prediction of 5/12. Body mass scaling exponents of P (scope) differed significantly from 0 in all cases, and so P (scope) showed a positive body mass scaling in birds in accordance with the prediction.
Department of Theoretical Ecology, Lund University, Ecology Building, 223 62, Lund, Sweden. anders.hedenstrom@teorekol.lu.se
Anders
A
Hedenström
D000818:Animals; D001481:Basal Metabolism / Q000502:physiology*; D001522:Behavior, Animal / Q000502:physiology; D001696:Biomechanical Phenomena; D001717:Birds; D015992:Body Mass Index; D005426:Flight, Animal / Q000502:physiology*; D008954:Models, Biological; D010802:Phylogeny