Social Structure of the Japanese Wagtail Motacilla grandis

1. Social Behaviour and Spatial Structure

抄録

The vocalization of the Japanese wagtail was classified into location call, warning call, threatening sound and song, each being composed of basic sounds and phrases. The epigamic behavioural sequence to copulation was related to the following behaviours: Female-appeasement display, flying courtship display and repelling; Male-courtship display, bill opening and back showing. Aggressive behaviours (chasing, threatening and physical combat) were most frequently observed between the same sexes. The most intensive exclusiveness was also seen between the same sexes showing the above aggressive behaviours. Spatial relationships between the song and two aggressive behaviours (chasing and threatening) were interpreted in relation to 1) the area which an owner tried to occupy, 2) the dominance relationship between the owner and others which tried to intrude, and 3) the aggressive area where the owner's aggressiveness existed. The border line of territory as "any defended area" was defined here as the outer limit of aggressive area where the neighbour was absent and as the positions of mutual threatening where the neighbour existed.