REDUCTION OF AGGRESSION AMONG DOMESTIC HENS (GALLUS-DOMESTICUS) IN THE PRESENCE OF A DOMINANT 3RD PARTY

Experiments by earlier authors were repeated and extended to examine, in white leghorn chicken (Gallus domesticus), the underlying mechanisms of the reduction of aggressive behaviour between two subordinate hens in the presence of a third, dominant group member (cock or alpha hen). Analysis of accompanying changes in feeding time showed that the inhibition caused by the cock's presence is aggression-specific (though its nature is still unknown), while the alpha hen, as an aggressive competitor, restricts the subordinates' access to food so that they lack the resource they would defend. The evidence suggests that, with the cock as well as the dominant hen, the low rate of aggression in subordinates is not due to a lack of time for attacks but rather to a lack of aggressive motivation.