Ventilated Capsule Measurements of Cutaneous Evaporation in Mourning Doves

To determine the contribution of cutaneous water loss to evaporative cooling in Mourning Doves (Zenaida macroura), we used a ventilated capsule technique to measure evaporation from the breast, back, and axilla of captive doves at 25 and 35°C. Water loss from these surfaces averaged 4.1 ± 0.4 mg m-2 sec-1 (SE) at 25°C and was highest from the dorsum. At 35°C, cutaneous evaporation increased to 8.3 ± 0.9 mg m-2 sec-1. Mean skin water-vapor diffusion resistance of the breast, back, and axilla together was 111.5 ± 9.5 sec/cm at 25°C and decreased significantly to 69 ± 8.0 sec/cm at 35°C. The large increases in cutaneous evaporation we observed between 25 and 35°C result mainly from temperature-dependent reductions in the skin resistance to water loss. Our results suggest that augmented cutaneous evaporation is utilized as a means of heat defense by Mourning Doves.