定量评估豢养长江江豚个体间的优势关系

2000年1—4月和2000年4月—2002年4月,分别连续3个月和2年观察了中国科学院水生生物研究所白鱀豚馆6头长江江豚（3雌3雄,8个不同组合群）个体间发生的3种交互关系,即接近—逃开、接近—接触和接近—尾鳍击打。在累计8,162min的观察时间内,共观察到这些交互关系1,685次。本研究将江豚个体间发生的这3种交互关系作为个体间优势关系的指示,并分别给交互双方赋予不同的分值,采用优势比分矩阵方法定量分析了江豚个体之间的优势关系。结果表明江豚群体内存在优势关系。同性别个体之间,优势关系与年龄和饲养时间有关,年龄大的个体比年龄小的个体具有优势,饲养时间短的个体比饲养时间长的个体具有优势。但是,异性成年个体之间,优势关系通常是可变的。

A quantitative assessment of dominance relations among the captive Yangtze finless porpoises (Neophocaena phocaenoides asiaeorientalis)

This study was designed to investigate whether dominance relations exist among captive Yangtze finless porpoises (Neophocaena phocaenoides asiaeorientalis) and how the relations establish, as well as how porpoises maintain the relations stable.The studied captive porpoise group was kept in Baiji Dolphinarium of Institute of Hydrobiology of the Chinese Academy of Sciences, and consisted of three females (two adults and one calf) and three males (two adults and one subadult).Successively, the porpoises were randomly put into eight small groups with different compositions during the study, and were kept in three indoor pools with different dimensions.Three types of interactions, approach-flee, approach-contact and approach-tail flap occurred within each of the small groups were observed using focal sampling method from January to April 2000 and from April 2000 to April 2002, respectively.In all, 1,685 dyadic interactions were recorded during 8,162min of observation during 27-month study.The three types of interactions were used as identifications of dominance relations between pairs of individuals, and either opponent of each pair was assigned different dominant scores in different interactions.Dominance relationships between individuals were analyzed quantitatively using a method of dominant score matrix.Results indicated that dominance relationships among males or females were influenced by the age and captive duration of participants.Old porpoises were dominant to young ones; short-term captive individuals were dominant to long-term captive ones.In contrast, dominance relationships between adult males and females were changeable.