本研究では, 複雑な社会行動が進化している鳥類カラスを対象に, 情動が介在する社会行動機能と生理機構の解明を行った. カラスの飼育群れ内および2個体間で生じる競合・宥和行動について, (1) 行動機能, (2) 行動調節機構, (3) 自律神経系の関与を調べた. (1) では, 飼育群れの社会行動の長期データから, 同性個体間の利他的羽繕いが, 優位性誇示の機能を持つことを発見した. (2)では, 3個体同時交渉における個体間距離を解析し, 1位個体の存在が, 他の2個体間の距離を近づけることを見出した. (3) では, 交渉中のカラスの心拍を計測し, 優位個体との対面によって, 劣位個体は副交感神経優位な活動になることを見出した.
This research project aimed to examine the social function and physiological mechanisms of social behaviour of crows. We found primarily three findings. First, analysis of long-term behavioural data from group-housed crows suggested that allopreening within same-sex individuals functions as a dominance signal function. Second, analysis of inter-individual distance in a social interaction involving three individuals revealed that the presence of the 1st dominant male caused the distance between the other two individuals to be close. Third, based on EEG data recorded from freely interacting crows, heart-rate variability analysis uncovered that subordinate crows showed the lower heart rate and higher rMSSD during the interaction with dominant birds than during being alone, indicating the involvement of the parasympathetic autonomic nervous system in social interaction of subordinate birds.
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