TUCKER, VANCE A. Metabolism during flight in the laughing gull, Lams atricilla. Am. J. Physiol. 222(2): 237-245. 1972.-The mean metabolic rates of two laughing gulls (mean body mass, 0.30 kg) flying in a wind tunnel were between 23 and 38 w/kg0*325 depending on flight speed and angle of flight. A change in the intensity of air turbulence in the tunnel from 0.88 to 1 .44y0 had little effect on the mean metabolic rate in flight. The drag of the mask and tube carried by the gulls increased metabolic rates by as much as 10 %. The metabolic rates reported for budgerigars flying in a wind tunnel in a previous study are reduced as much as 18 y0 after correction for the drag of the mask and tube. The metabolic rates of the gulls in level flight, after correcting for the drag of the mask and tube, were 6-8 times the metabolic rates of the gulls resting at temperatures between 25 and 35 C, and 12-14 times the mean basal metabolic rate of nonpasserine birds of the same size. The rate of wing flapping was almost constant at 3.8 flaps/set, irrespective of flight speed, and the mean respiratory frequency in flight was 2.5 breaths/set.