Interaction of operant behaviour and autonomic thermoregulation in the domestic fowl.

1. Domestic fowls were trained to peck a disc in order to receive a limited thermal reinforcement. 2. When subsequently tested, their use of the operant response was a function of ambient temperature, decreasing from 0 to 24 degrees C and rising again steeply from 28 to 42 degrees C. 3. Under cool conditions changes in rate of heat production were of major significance in maintaining homeothermy, whilst in the heat the operant response was used in preference to, or in addition to, thermal panting. 4. Data from the behavioural studies, together with those on autonomic effector mechanisms, indicate that optimal thermal conditions for the fowl are likely to be attained at 22 to 24 degrees C.