著者

一方井 祐子 伊澤 栄一

出版者

慶應義塾大学大学院社会学研究科

雑誌

慶應義塾大学大学院社会学研究科紀要 : 社会学・心理学・教育学 : 人間と社会の探究 (ISSN:0912456X)

巻号頁・発行日

no.73, pp.49-55, 2012

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論文Affiliative social interactions play a crucial role in the formation and maintenance of social bonding in the form of a cooperative relationship among group members in a wide range of social animals. Behavioural functions of affiliative interactions have been extensively investigated in mammals including primates and carnivores, but little is known about such behavioural functions in birds. Because many bird species form and maintain male‒female pair bonding as a cooperative social unit, they are good animal models to study the evolution of cooperative behaviour. In this study, we investigated the involvement of affiliative interactions in the formation and maintenance of pair bonds in a life-long monogamous bird, budgerigar (Melopsittacus undulatus). To verify the involvement of these interactions, we compared the frequency of affiliative interactions between pair bonded and non-pair bonded male‒female dyads over 3 months after introducing a novel flock. To characterize the potential frequency change in affiliative interactions, a similar comparison was conducted for aggressive interactions. We observed that affiliative interactions drastically increased together with pair bond formation 2 weeks after introducing the flock and decreased thereafter. However, a certain high frequency level of affiliative interactions was maintained even after pair bond formation. In contrast, aggressive interactions were observed to transiently increase along with pair bond formation but gradually disappeared thereafter. No such change was found in non-pair bonded male‒female dyads in both affiliative and aggressive interactions. These results suggest that affiliative interactions are involved in pair bond formation and maintenance.