Conditioned response to magnetic anomaly in the Pekin duck (Anas platyrhynchos domestica) involves the trigeminal nerve.

There have been recent calls to develop protocols that collect unambiguous measures of behaviour using automatic techniquesin conditioning experiments on magnetic orientation. Here, we describe an automated technique for recording the behaviour ofPekin ducks in a conditioning test that allows them to express unrestricted searching behaviour. Pekin ducks were trained to findhidden food in one corner of a square arena below which was placed a magnetic coil that produced a local magnetic anomaly.The trigeminal nerve was anaesthetised by injection of lignocaine hydrochloride 2'3'mm caudal to the medial canthus of each eye,medial to the globe, prior to the presentation of unrewarded tests. Lignocaine-treated ducks showed no initial preference for themagnetic anomaly whereas saline-treated control ducks showed a significant preference at the same age. A second experimentwas undertaken in which the trigeminal nerve was surgically severed and 2'3'mm removed, and this surgery abolished thepreviously observed preference for the corner with the magnetic coil in a small number of ducks. These data show that Pekinducks are able to detect and use magnetic stimuli to guide unrestricted search behaviour and are consistent with a hypothesis ofmagnetoreception involving a putative cluster of magnetite in the upper beak.