Fig. 1. Logarithmic plots of daily total evaporative water loss (g day^-1) as a function of body mass. As evaporative water loss from birds is sensitive to ambient temperature, Equation 2 was used to adjust both plotted data and the regression line to a nearly thermally neutral 25°C for comparison with simple and phylogenetic allometric regression models for birds in thermally neutral conditions (equations 2 and 7 in Williams, 1996).