Chickens orient using a magnetic compass

Although behavioural experiments show that a wide range of animals use the earth's magnetic field as a compass for orientation, evidence from conditioning experiments has proved elusive. In birds, the only two successful attempts of operant conditioning to magnetic stimuli both involved magnetic anomalies rather than changes in magnetic direction. By using the young domestic chick's motivation to locate a hidden social stimulus, we have demonstrated the first conditioned magnetic compass response in birds and show that the ability to orient using magnetic cues has been retained after thousands of years of domestication. Eight layer-strain domestic chicks were imprinted on a red table tennis ball and subsequently trained to locate this ball hidden behind one of four screens in the north, east, south or west corners of a square arena (Figure 1A). Each chick was released in the centre of the arena to search for the ball that had been hidden behind one of the screens. After finding the ball and remaining with it for one minute (reward), the chick was returned to the home pen while the arena was rotated. The chick was re-introduced after approximately 2-5 minutes into the arena for the next trial to locate its reward. Training continued until the chick approached the ball without deviation in three consecutive training trials (criterion). Unrewarded tests - no ball hidden behind screen - followed, in which we recorded the direction of the first screen that the chick walked behind.