Evaporative water loss from endotherms in thermally and hygrically complex environments: An empirical approach for interspecific comparisons

Summary Evaporative water loss was measured from black-tailed prairie dogs (Cynomys ludovicianus) at eight air temperatures between 10 and 40°C, and over a broad range of humidities at each temperature. Evaporation increased, decreased, or remained constant below thermoneutrality, depending on humidity, and increased at higher temperatures indirectly with humidity. Evaporation was negatively related to humidity at different temperatures with a series of linear regressions that provided for statistical comparisons. Significantly different intercepts and slopes at different temperatures occurred for prairie dogs, and for deer mice (Peromyscus maniculatus) and house mice (Mus musculus) using published data. A general model, based on the equation for a straight line, was developed to relate evaporation to humidity; the intercept and slope were empirically derived mathematical functions of temperature. The model provided three-dimensional graphic responses for evaporation that showed different interactions between temperature and humidity for the three species.