A device for monitoring position of unrestrained animals in a temperature gradient

The design and use of an automated system which permits continuous monitoring of the position of an animal in a temperature gradient is demonstrated. Animal position in the gradient is detected with phototransistors. Through simple electronic switching, the information from the phototransistors is converted to an analog DC signal that is directly proportional to the position of the animal in the temperature gradient. The temperature gradient method permits continuous automated monitoring of thermoregulatory behavior in unrestrained animals.