Mitra Setia Tatang, van Schaik Carel P
Fakultas Biology, Universitas Nasional, Jakarta, Indonesia.
Folia Primatol (Basel). 2007;78(4):215-26. doi: 10.1159/000102317. Epub 2007 May 9.
Flanged male orang-utans emit loud vocalizations called long calls. In this study, we examined the correlates of variation in long-calling rates among flanged male Sumatran orang-utans, as well as the ranging responses of adult females and flanged males to these long calls. Males that gave calls more often were more likely to approach calls by others. Results bolster a female attraction function of long calls. Flanged males did not significantly avoid or approach long calls. However, males called more when alone than when guarding a female mate, and adult females significantly approached long calls, especially those of the dominant male, and did so regardless of their reproductive state, allowing them to remain within earshot of calling males. The possible selective advantages of this response include avoidance of harassment and infanticide by males. These findings confirm the existence of some form of social organization above the mother-infant unit.
有凸缘的雄性猩猩会发出一种叫做长叫的响亮叫声。在本研究中，我们调查了有凸缘的苏门答腊雄性猩猩长叫频率变化的相关因素，以及成年雌性和有凸缘的雄性对这些长叫的活动范围反应。叫得更频繁的雄性更有可能接近其他雄性发出的叫声。结果支持了长叫具有吸引雌性的功能。有凸缘的雄性并没有明显避开或接近长叫。然而，雄性在独处时比守护雌性配偶时叫得更多，成年雌性会显著接近长叫，尤其是占主导地位的雄性发出的长叫，而且无论其生殖状态如何都会这样做，以便它们能留在能听到雄性叫声的范围内。这种反应可能的选择优势包括避免受到雄性的骚扰和杀婴行为。这些发现证实了在母婴单元之上存在某种形式的社会组织。
