Social interactions in Red Junglefowl ( Gallus gallus ) and White Leghorn layers in stable groups and after re-grouping

1. Although social behaviour is a major factor affecting the coping of poultry in production environments little is known about how it has been affected by intensive selection processes in fowl. We attempted to clarify selection effects on overall repertoire and occurrence of different social behaviours as well as on aggressive responses to re-grouping with unfamiliar birds by comparing high-producing White Leghorn layers to wild type Red Junglefowl. 2. In the first experiment we observed 8 stable mixed sex groups/breed each consisting of four 24-week-old birds previously familiar to each other. During 9 consecutive days, a wide range of social signals, sexual and aggressive interactions as well as spacing behaviour and activity were recorded over a 12-h photoperiod. 3. In the second experiment, starting at 19 weeks of age, 16 single sex groups of three birds from each breed were formed by mixing unfamiliar individuals. Aggressive behaviours were recorded 0, 5, 24 and 48?h after re-grouping. 4. Results from the stable groups indicated that the repertoire of social behaviours has been preserved during selection with few changes in frequencies and intensities. However, Leghorns showed a more cohesive spacing pattern than junglefowl. 5. In the second experiment, aggressive activity was higher immediately and after 24?h following re-grouping in Leghorns, but there was a drop in the aggressiveness at 5?h to the same level as junglefowl. We suggest that this may indicate poorer social learning capacity with a weaker ability to cope with group disruptions compared to the ancestral breed.