Inter-individual relationships in proboscis monkeys:a preliminary comparison with other non-human primates

Ikki Matsuda, Augustine Tuuga, Henry Bernard and Takeshi Furuichi

今までテングザルにおける，個体識別に基づいた詳細な行動観察は行われてこなかったため，本研究により多くの新しい知見を得ることが出来た．2005年から2006年にかけて，マレーシア・サバ州において，テングザル1群（オトナ♂:1，オトナ♀：6，未成熟個体：9）のオトナ個体の社会交渉を個体追跡法により記録した（観察時間　♂：1,968h，♀：1,539h）．解析の結果，群内の個体間には希薄ながらも優劣関係が認められたが，個体間の毛づくろいの方向性には優劣関係は反映されていないことが明らかになった．また，テングザルの毛づくろいネットワークを，他の霊長類（ハヌマンラングール；カップドラングール；ニホンザル；ボノボ；チンパンジー）と比較・検討した結果，テングザルのネットワークは，父系，双系社会の霊長類種と類似していることがわかった．母系的な社会が示唆されてきたテングザルだが，本解析と，実際にオス・メスの移出入が報告されていることなどから，テングザルは双系タイプの社会の特徴を保持していることが明らかとなった． 

http://www.springerlink.com/content/086762238q564rr4/

Primates (in press: DOI: 10.1007/s10329-011-0259-1);

This is the first report on inter-individual relationships within a one-male group of proboscis monkeys (Nasalis larvatus) based on detailed identification of individuals. From May 2005 to 2006, focal and ad libitum data of agonistic and grooming behaviour were collected in a forest along the Menanggul River, Sabah, Malaysia. During the study period, we collected over 1,968 h of focal data on the adult male and 1,539 h of focal data on the six females. Their social interactions, including agonistic and grooming behaviour, appeared to follow typical patterns reported for other colobines: the incidence of social interaction within groups is low. Of 39 agonistic events, 26 were displacement from sleeping places along the river, 6 were the α male threatening other monkeys to mediate quarrels between females and between females and juveniles, and 7 were displacement from feeding places. Although the agonistic behaviour matrix based on the 33 intra-group agonistic events (excluding events between adults and juveniles and between adults and infants) was indicative of non-significant linearity, there were some specific dominated individuals within the group of proboscis monkeys. Nonetheless, grooming behaviour among adult females within a group were not affected by the dominance hierarchy. This study also conducted initial comparisons of grooming patterns among proboscis monkeys and other primate species. On the basis of comparison of their grooming networks, similar grooming patterns among both-sex-disperse and male-philopatric/female-disperse species were detected. Because adult females in these species migrate to groups repeatedly, it may be difficult to establish the firm grooming exchange relationship for particular individuals within groups, unlike in female-philopatric/male-disperse species. However, grooming distribution patterns within groups among primate species were difficult to explain solely on the basis of their dispersal patterns. Newly immigrated females in some species including proboscis monkeys are eager to have social interactions with senior group members to improve their social position.

http://www.springerlink.com/content/086762238q564rr4/

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