Figure 3.
Conceptual model (thick black line) for the expected physical relationship between evaporative water loss (EWL) and water vapour pressure deficit (Δwvp), based on diffusion (Fick's law), compared with the relative EWL for various endotherms from the literature (numbers indicate source). The Δwvp is calculated as ((100 − ambient RH)/100)*saturation water vapour pressure at the ambient temperature. EWL is scaled for each species, so that the EWL for the lowest measured Δwvp fits on the expected physical model line. Data that fall below the expected physical line are consistent with a regulated decrease in EWL (i.e. water conservation), whereas data that fall above the expected physical line are consistent with an increased EWL at higher Δwvp (i.e. enhanced water loss).