Maternal aggression and inter-individual distance in the broody hen (Gallus gallus).

The broody hen behaves in an aggressive way towards other hens. Pairs of either two broody hens, or two non-broody hens, or one broody and one non-broody hen, were observed in a small enclosure. Pecking of pen mates was found in pairs of broody hens while no pecking was found in pairs of non-broody hens. In pairs of one broody and one non-broody hen only the broody hen did aggressive pecking. Pairs of broody hens keep at a greater distance from each other than pairs of non-broody hens. It is suggested that these behaviours function to maintain the brood as a discrete unit and facilitate the development and maintenance of the hen-chick relationship.