Different responses of two strains of chickens to different training procedures for magnetic directions.

In previous conditioning experiments training domestic chickens to magnetic directions, a brown strain solved the task, whereas a white strain seemed unable to do so (Freire et al. Anim Cogn 11:547-552, 2008). To test whether this was possibly caused by loss of magnetic compass orientation in the white chickens, we analyzed the distribution of cryptochrome 1a, the candidate receptor molecule mediating magnetic compass information, in the retinae of Lohmann Browns and White Leghorns and found no difference between the two strains. Yet, subsequent training experiments replicated the former findings: Lohmann Browns used the magnetic field to find an imprinting stimulus hidden behind the screen in a specific magnetic direction, whereas White Leghorns did not solve the task. However, when we altered the training method by training also in a magnetic field with North shifted to geographic East and including a punishment for incorrect choices, the performance of White Leghorns improved to a significant preference for the expected directions. The Lohmann Browns, on the other hand, seemed frightened and chose randomly. Our results thus demonstrate the crucial role of the training method for conditioning to magnetic stimuli, with differences found even between strains of the same species.