Social Factors Influencing the Hierarchies of Small Flocks of the Domestic Hen: Interactions between Resident and Part-Time Members of Organized Flocks

Abstract

The interactions between members of organized groups of White Leghorn hens and newcomers to the group, and between hens which were permanently present and those with the group for only part of the time, were studied for a period of 2 years using a total of 12 flocks and 80 hens. The initial hierarchy was first ascertained in each flock, then 2 hens were removed from a given flock, introduced into a 2d group for a time, and returned to the original hierarchy for short periods of time at regular intervals. In this way 7 hens were moved between 2 flocks. In some cases this procedure was repeated so that another 7 hens were rotated between 3 flocks, 2 hens between 4 flocks, and 4 hens were rotated between 5 flocks. In most cases a rotated hen held a different status in the social hierarchy of each flock in which it was a member. Interrelations between permanent and intermittent members showed that, although subordinate newcomers at first were not allowed to mingle with the flock members, within 3 to 6 weeks they became assimilated members of the group, while dominant newcomers apparently became assimilated within 3 days of their introduction. Once assimilated, the part-time members mingled with the other hens and behaved in the same way as hens permanently present with similar social status. In 10 of the 44 introductions of hens which were already members in at least one other group, the newcomer failed to become assimilated. These non-assimilated individuals were not allowed to join in the flock activities such as feeding, nesting, etc. There was evidence of cooperation between partner-birds which were moved together into strange flocks. The dominant of the pair did not usually peck its partner. When one hen of a pair was dominant to a resident, it would frequently peck that resident when the latter pecked the subordinate partner. In one group in which the members were together for only 1 hr. on alternate days, the flock organization was, nevertheless, maintained throughout the 11 months of observations. After 2 of the experimentally rotated hens were each implanted with a pellet of testosterone propionate, they rose in the social hierarchy of each of 5 flocks in which they were members.