Learning of magnetic compass directions in pigeons

Abstract

A proof of magnetic compass learning by pigeons under laboratory conditions has been attempted for decades, but all experiments have failed so far. The aim of the present study was to test whether pigeons can learn magnetic compass directions in an operant chamber if magnetic cues are presented as true spatial cues. Experimental sessions were carried out in the local geomagnetic field and in magnetic fields with matched total intensity and inclination, but different directions generated with Helmholtz-coils. Birds demonstrated successful learning with a performance level comparable to that in learning studies with magnetic anomalies. In addition, we compared the data from magnetic learning in the laboratory with performance from homing experiments in the field. The birds that were more successful in the learning experiment had vanishing bearings farther away from the home direction than the group mean at unfamiliar, but not at familiar sites. This might suggest that better learners explore unknown locations in a different way. Our findings represent the first evidence for operant magnetic compass learning in pigeons and also provide a link between behavioural data from the field and the laboratory.

Conditioned discrimination of magnetic inclination in a spatial-orientation arena task by homing pigeons (Columba livia)

“…Previous successful magnetic conditioning studies with pigeons had trained the animals to discriminate magnetic anomalies, which consisted of both changes in magnetic intensity and inclination, and were generated either by magnetic coils or a group of bar magnets (Mora et al, 2004;Thalau et al, 2007;Freire et al, 2012). Studies with homing pigeons (Wilzeck et al, 2010) as well as two other bird species, the domestic chicken (Gallus gallus) (Freire et al, 2005) and zebra finch (Taeniopygia guttata) (Voss et al, 2007;Keary et al, 2009), conditioned the birds to a shift in the horizontal component of the magnetic field.…”

“…Previous attempts to condition homing pigeons or other birds to magnetic stimuli have focused either on magnetic anomalies, which varied both in magnetic intensity and inclination in an uncontrolled way (Mora et al, 2004;Thalau et al, 2007;Freire et al, 2012), or on changes in the horizontal component (Freire et al, 2005;Voss et al, 2007;Keary et al, 2009;Wilzeck et al, 2010). To investigate whether homing pigeons could be trained to discriminate differences in magnetic field inclination only, we developed a behavioral conditioning paradigm that required pigeons to discriminate changes in magnetic inclination to obtain a food reward in a spatial-orientation arena task.…”

Functional MRI and functional connectivity of the visual system of awake pigeons

“…In addition, the ophthalmic branch of the trigeminal nerve is activated by a changing magnetic-field stimulus and relays this information to the bird brainstem [49]. It is likely that also pigeons sense the magnetic field in terms of a magnetic compass and/or local magnetic deviations [25,50,51]. In this case, our pigeons possibly perceived a visual and a trigeminal stimulation that accompanied the changes of the strong magnetic field within the scanner.…”

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

“…Conditioning birds to respond to magnetic direction has similarly only recently been achieved by training animals to move in a certain magnetic direction in order to obtain a reward (Freire et al, 2005;Voss et al, 2007;Wilzeck et al, 2010). This response appears to be modulated by chemical reactions that respond to Earth-strength magnetic fields and forms the basis of the avian magnetic compass (Rodgers and Hore, 2009).…”