Thermal sensitivity of different skin areas in pigeons

Abstract

Pigeons lightly anaesthetized with urethane regulate their body temperature at a hypothermic level. During recovery from anaesthesia there is a continuous shivering at an ambient temperature of about 22 °C. The effect of thermal stimulation (radiant heat) of different skin areas on this ongoing shivering (EMG of the breast muscle) was taken as a measure of the thermal sensitivity of the skin area under study. Feathered skin areas, which were plucked before stimulation, turned out to be very sensitive with regard to the thermoregulatory effector mechanism of shivering. Moderate heating of the most sensitive skin of the back often resulted in cessation of shivering. Similar feathered skin areas on back, wing, and breast showed that there was a decreasing sensitivity in that order they are mentioned. Graded stimulation was followed by a graded response and there was an interaction between different skin areas. Heating the beak caused only a small reduction of shivering. There was no effect at all during heating or cooling naked parts of the feet even during painful thermal stimulation which was often followed by retraction of the whole leg.