We measured brain and colonic temperatures in adult pigeons (Columba livia) with or without oesophageal ligation, and with or without simultaneous eye covering at ambient temperatures between 24 degrees C and 45 degrees C. 2. Colonic and brain temperatures rose at the higher ambient temperatures; the temperature elevations were no different in pigeons with oesophageal ligation, compared to sham-operated controls. The presence of simultaneous eye covering also had no effect on colonic or brain temperatures. 3. Oesophageal inflation decreased from a rate of 2.8 +/- 1.4 per minute (mean +/- SEM) to zero, in anaesthetized pigeons when warmed from a colonic temperature of 40.5 degrees C to 43.8 degrees C. 4. In pigeons oesophageal inflation plays no significant part in body temperature regulation or in the maintenance of a lower brain than body temperature even in hot ambient conditions.
