Induced power is calculated following Pennycuick(1989) with the mean wing span and mass from Table 3 and flight speed from Table 2. The induced power factor k is taken as its default value of 1.2. Muscle-mass specific powers are calculated assuming that the pectoralis dominates downstroke power and constitutes 18% of body mass. Muscle force and stress are calculated using the wing geometry (specifically the shoulder to delto-pectoral crest distance and the cross section of the pectoralis) from pigeons used in other studies (Dial and Biewener, 1993; Biewener et al. 1998; Soman et al.,2005) scaled to the mean body mass of the wild-type pigeons used here, for which a value of 7.385 cm² was used for the physiological cross-sectional area of the muscle. These values, therefore, should be considered approximate.