Behavioural consequences of divergent selection on general locomotor activity in chickens.

•Hens from lines selected divergently on activity over 8 generations were examined.•These hens were found to differ significantly in the level of activity.•These heritable changes in activity were accompanied by changes in fearfulness.•Hens selected for high activity were more fearful than those selected for low activity.•Social behaviour was not affected by selection on general locomotor activity.