The role of wingbeat frequency and amplitude in flight power

Body-mounted accelerometers provide a new prospect for estimating power use in flying birds, as the signal varies with the two major kinematic determinants of aerodynamic power: wingbeat frequency and amplitude. Yet wingbeat frequency is sometimes used as a proxy for power output in isolation. There is, therefore, a need to understand which kinematic parameter birds vary and whether this is predicted by flight mode (e.g. accelerating, ascending/descending flight), speed or morphology. We investigate this using high-frequency acceleration data from (i) 14 species flying in the wild, (ii) two species flying in controlled conditions in a wind tunnel and (iii) a review of experimental and field studies. While wingbeat frequency and amplitude were positively correlated, R 2 values were generally low, supporting the idea that parameters can vary independently. Indeed, birds were more likely to modulate wingbeat amplitude for more energy-demanding flight modes, including climbing and take-off. Nonetheless, the striking variability, even within species and flight types, highlights the complexity of describing the kinematic relationships, which appear sensitive to both the biological and physical context. Notwithstanding this, acceleration metrics that incorporate both kinematic parameters should be more robust proxies for power than wingbeat frequency alone.Fil: Krishnan, Krishnamoorthy. Swansea University; Reino UnidoFil: Garde, Baptiste. Swansea University; Reino UnidoFil: Bennison, Ashley. University College Cork; IrlandaFil: Cole, Nik C.. No especifíca;Fil: Cole, Emma L.. Swansea University; Reino UnidoFil: Darby, Jamie. University College Cork; IrlandaFil: Elliott, Kyle H.. McGill University; CanadáFil: Fell, Adam. University Of Stirling; Reino UnidoFil: Gómez Laich, Agustina Marta. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: de Grissac, Sophie. No especifíca;Fil: Jessopp, Mark. University College Cork; IrlandaFil: Lempidakis, Emmanouil. Swansea University; Reino UnidoFil: Mizutani, Yuichi. No especifíca;Fil: Prudor, Aurélien. Centre National de la Recherche Scientifique; FranciaFil: Quetting, Michael. No especifíca;Fil: Quintana, Flavio Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; ArgentinaFil: Robotka, Hermina. No especifíca;Fil: Roulin, Alexandre. Universite de Lausanne; SuizaFil: Ryan, Peter G.. University of Cape Town; SudáfricaFil: Schalcher, Kim. Universite de Lausanne; SuizaFil: Schoombie, Stefan. Universite de Lausanne; SuizaFil: Tatayah, Vikash. No especifíca;Fil: Tremblay, Fred. McGill University; CanadáFil: Weimerskirch, Henri. Centre National de la Recherche Scientifique; FranciaFil: Whelan, Shannon. McGill University; CanadáFil: Wikelski, Martin. No especifíca;Fil: Yoda, Ken. No especifíca;Fil: Hedenström, Anders. Lund University; SueciaFil: Shepard, Emily L. C.. Swansea University; Reino Unid