Coherent use of information by hens assisting to the victory or defeat of their former dominant by a stranger: a case of transitive inference?

Abstract

We examine the role of observation during the formation of triads in females of the domestic fowl. During hierarchy formation, a hen observing agonistic interactions and conflict settlement between its former dominant and a stranger uses this information when in turn confronted by the latter. Under a first condition, bystanders witnessed their prior dominant being defeated by a stranger before being introduced to them. In a second condition, bystanders witnessed the victory of their prior dominant over a stranger. In a third condition, bystanders witnessed two strangers establishing a dominance relationship before being introduced to their prior dominant and to a stranger the former had just defeated. It was found that behavioural strategies of bystanders depended on the issue of the conflict they had just witnessed. Bystanders which had attended to the defeat of their prior dominant behaved as having no chance of defeating the stranger. They never initiated an attack against it, and upon being attacked, readily submitted in turn to the stranger. On the contrary, bystanders which had witnessed the victory of their prior dominant over the stranger behaved as having some chances against the stranger. They initiated attacks in 50% of cases, and won 50% of conflicts against the stranger. When bystanders had not attended the meeting of their prior dominant, they first initiated contact with the strangers in only 27% of cases, which approximates the average of their chances for defeating the stranger. However, bystanders finally defeated the strangers in 40% of cases. These results suggest that bystanders which had witnessed the encounter of their prior dominant with the stranger had gained some information on the relationship established between them. When confronted in turn to the stranger, observers used this information coherently, perhaps through transitive inference, thus contributing to the existence of transitive relationships within the triads. It is proposed that observational or vicarious learning could account for «transitive inference» in this case: the observer would simply reproduce the behaviour the prior dominant had shown towards the stranger. The paper in in French