Ventilated Capsule Measurements of Cutaneous Evaporation in Mourning Doves

Abstract

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 350C. Water loss from these surfaces averaged 4.1 ? 0.4 mg m-2 sec-' (SE) at 250C and was highest from the dorsum. At 350C, cutaneous evaporation increased to 8.3 ? 0.9 mg m-2 sec-'. Mean skin water-vapor diffusion resistance of the breast, back, and axilla together was 111.5 ? 9.5 sec/cm at 250C and decreased significantly to 69 ? 8.0 sec/cm at 350C. The large increases in cutaneous evaporation we observed between 25 and 350C result mainly from temperaturedependent 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.