中文摘要：

海南长臂猿（Nomascushainanus）是野外研究最少的长臂猿种类之一。在过去的十多年中，只了解其种群数量、种群结构、栖息地和有关于其食物种类的极少量信息。对于世界上最濒危的灵长类之一的海南长臂猿，在长达4年的野外研究中，主要采用扫描取样法和焦点动物取样法观察到了4次海南长臂猿的合群现象，并发现了现存的两群海南长臂猿之间的合群行为不同于其他长臂猿，如白掌长臂猿（Hylobateslar）的合群行为。在海南长臂猿的合群行为中，只观察到了雌雄性成年个体和雄性亚成体以及青年雄性个体之间的呜叫和追逐行为，而没有发现像白掌长臂猿样的两群体成员问的玩耍和理毛行为，更没有偷情行为和白掌长臂猿那样致命的激烈打斗行为的存在，即只存在着呜叫行为和竞争性行为。两群体的雌性成年母猿根本就不参与到追逐行为中，它们只是在相距合群行为发生地点20一30m处休息和观望。同时，海南长臂猿相遇的持续时间也不像其他种类的长臂猿那样长，只有24—51min。另外，也没有发生打斗行为。对于海南长臂猿雌雄性成年个体在群体相遇时的行为，我们认为是它们对其领域的保护，而未成年个体则是通过参与这种追逐方式学习如何保护自己今后的领域。

英文摘要：

The Hainan gibbon （Nomascus hainanus） is one of the most endangered primates and the least studied gibbon species in the fieldwork. In the past decades only a little information was known about its population size, population structure, habitat and food kinds. Through four years field work, we observed their inter-group encounters for four times. We found that their encounter behaviors were much different from other gibbon species. Only vocal and chasing behavior happened between the adult females, male sub-adults and male juveniles of the Hainan gibbon encounters. The time of inter-group encounters was much shorter than other gibbon species, just 24-51 minutes. Not like the Hylobates lar encounters, no fighting was observed among the Hainan gibbon encounters; there was also no such behaviors as playing and grooming, even the extra-group-copulations. The adult females of two groups didn＇t take par in the chasing and they only rested and watched 20-30m away. We speculated that the behavior of the adult females may be interpreted as protecting their territory and by the way of chasing the sub-adults can learn how to protect their territory in the future.