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

Effects of Maternal Care During Rearing in White Leghorn and Brown Nick Layer Hens on Cognition, Sociality and Fear

Both genetic background and maternal care can have a strong influence on cognitive and emotional development. To investigate these effects and their possible interaction, White Leghorn (LH) and Brown Nick (BN) chicks, two hybrid lines of layer hen commonly used commercially, were housed either with or without a mother hen in their first five weeks of life. From three weeks of age, the chicks were tested in a series of experiments to deduce the effects of breed and maternal care on their fear response, foraging and social motivation, and cognitive abilities. The LH were found to explore more and showed more attempts to reinstate social contact than BN. The BN were less active in all tests and less motivated than LH by social contact or by foraging opportunity. No hybrid differences were found in cognitive performance in the holeboard task. In general, the presence of a mother hen had unexpectedly little effect on behavior in both LH and BN chicks. It is hypothesized that hens from commercially used genetic backgrounds may have been inadvertently selected to be less responsive to maternal care than ancestral or non-commercial breeds. The consistent and strong behavioral differences between genetic strains highlights the importance of breed-specific welfare management processes.

The magnetic compass of domestic chickens

In a recent paper, we showed that domestic chickens can be trained to search for a social stimulus in specific magnetic directions. Chickens can hardly fly and have only small home ranges, hence their having a functional magnetic compass may seem rather surprising. Yet considering the natural habitat of their ancestors and their lifestyle until recently, the advantages of a magnetic compass become evident.

Ontogenetic development of magnetic compass orientation in domestic chickens (Gallus gallus)

Domestic chickens (Gallus gallus) can be trained to search for a social stimulus in a specific magnetic direction, and cryptochrome 1a found in the retina has been proposed as a receptor molecule mediating magnetic directions. The present study combines immuno-histochemical and behavioural data to analyse the ontogenetic development of this ability. Newly hatched chicks already have a small amount of cryptochrome 1a in their violet cones; on day 5, the amount of cryptochrome 1a has reached the same level as in adult chickens, suggesting that the physical basis for magnetoreception is present. In behavioural tests, however, young chicks 5 to 7 days old failed to show a preference of the training direction; on days 8, 9 and 12, they could be successfully trained to search along a specific magnetic axis. Trained and tested again a week later, the chicks that had not shown a directional preference on day 5 to 7 continued to search randomly, while the chicks tested from day 8 onward preferred the correct magnetic axis when tested one week later. The observation that the magnetic compass is not functional before day 8 suggests that certain maturation processes in the magnetosensitive system in the brain are not yet complete before that day. The reasons why chicks that have been trained before that day fail to learn the task later remain unclear.