Fig. 3. The ratio of volumetric rate of buccopharyngeal evaporation to volumetric rate of oxygen consumption in Inca doves at four ambient temperatures. This evaporespiratory ratio was nearly quadrupled as ambient temperature increased from 30° to 42°C, indicating that birds were elevating buccopharyngeal evaporation above rates that would occur just as a result of breathing. There is no statistical difference between traces for `Unsealed' and `Sealed' trials. Values shown are means ± s.e.m. (N=8–12).