Agonistic behaviour influenced by strangeness, crowding and heredity in female domestic fowl ( Gallus gallus)

Abstract

Effects of strangeness, crowding and heredity on agonistic behaviour in the female domestic fowl were investigated. Strains differentiated for social dominance ability within each of two breeds were used. Significant differences were found between flocks within strain-treatment groups for several criteria of agonistic behaviour, indicating a critical need for adequate replication in such studies. Strangeness and crowding were associated with higher frequencies of social interaction than found in socially undisturbed and uncrowded flocks. Results suggested, however, that individual rates of social interaction were reduced by crowding. Distances between nearest neighbours, compared to distances expected with random distribution, were greater for crowded than for uncrowded flocks. Social interaction frequencies and variances of social tension indexes were greater within socially dominant strains indicating higher levels of social stress. A large breed difference in behavioural response to changing flock membership was found. However, strains within breeds failed to show differential responses in social interaction frequency, when subjected to changing flock membership or crowding.