The influence of social experience on the ontogenetic change in the relation between aggression, fear and display behaviour in black-headed gulls

Abstract

This study investigated whether changes in motivation of displays, occurring during normalontogeny in black-headed gulls, Larus ridibundus, are under the influence of social experience. To this end, birds were reared either in isolation or in groups of three. In the latter, the birds had social interactions, but did not show agonistic behaviour. The development of overt aggression and display behaviour was tested with a standard stimulus object, namely a stuffed or a live adult conspecific. In several aspects, the change in relation between aggression, fear and display was retarded in the experimental birds compared with that of control birds reared in a large group of at least nine birds. After re-housing in similar large groups, birds reared in isolation showed persistent deviations in frequency and orientation of agonistic and sexual behaviour. It is argued that the changes in motivation of display during ontogeny are influenced by specific experience with agonistic interactions, and may involve learning based on operant conditioning.