Functions of an unreported "rocking-embrace" gesture between female Japanese Macaques (Macaca fuscata) in Kinkazan Island, Japan.

Recently, research has focused on the effects of the concurrence of multimodal signals and their efficacy and meaning. We observed an unreported behaviour, a ventro-ventral "rocking-embrace" gesture that is always accompanied by lip smacking as the facial expression and sometimes by a girney call, in wild Japanese macaques (Macaca fuscata) living in Kinkazan Island, northern Japan. This study examined the form and contexts of the occurrence of such multimodal signals in order to elucidate its functions. Eighty-eight cases of rocking embrace were recorded during 183 h of observation over 22 days. Adult females were involved in all of the cases. Of the 71 cases between adult females in which behaviours prior to the rocking embrace could be identified, 13 cases were allogrooming interruptions, 11 were aggression, and 42 were approaches, most of which occurred between non-kin grooming partners. The rocking embrace was often followed by allogrooming. This suggests that rocking embraces occur under stressful conditions and may function to reduce tensions. This conclusion is consistent with the contexts and functions of lip smacking and girneys shown in previous studies. In contrast with lip smacking and girneys, neither a rocking embrace nor a ventro-ventral embrace (without rocking) between anoestrous adult females has been previously shown in Japanese macaques. In other macaque species, however, the latter gesture is often observed as an affiliative behaviour that immediately follows conflict; it functions to reconcile or as a greeting when it occurs immediately after an approach. Rocking embraces among the Kinkazan macaques occur in contexts similar to, and have a similar function to, the ancestral gesture of ventro-ventral embracing (which is hidden in Japanese macaques) and the ancestral display of lip smacking (which is still observed in Japanese macaques). The ventro-ventral embrace as a tactile signal might have been hidden since it was made redundant by the visual signal of lip smacking in ancestral macaques

Variation in Spatial Cohesiveness in a Group of Japanese Macaques (Macaca fuscata)

The spatial cohesiveness of a group is an important element that characterizes the social structure of group-living species. Moreover, remaining cohesive is crucial if individuals are to coordinate their activities and reach collective decisions. We measured interindividual spacing in a group of wild Japanese macaques (Macaca fuscata) to assess the spatial cohesiveness of a social group quantitatively. We used simultaneous focal animal sampling, with 2 observers recording individuals’ locations with a global positioning system (GPS) during 3 seasons. Interindividual distances differed among seasons; they were short in autumn (mean ± SD: 25.6 ± 20.1 m), intermediate in winter (mean ± SD: 46.3 ± 35.7 m), and long in summer (mean ± SD: 62.3 ± 47.1 m). Measurements taken in summer revealed extremely wide spacing (maximum: 1225 m), suggesting subgrouping. Distances also varied with activity during each season; they were short during resting and grooming, intermediate during foraging, and long during moving. Group cohesion was also influenced by food distribution. More group members were ≤20 m of the focal individual during foraging on clumped food than foraging on scattered food in each season, and the group foraged on clumped food most frequently in autumn. Individuals were also likely to aggregate at resting/grooming sites and clumped food patches and to disperse when moving within a day. These results demonstrate that Japanese macaques show considerable variation in spatial cohesiveness both within short time periods, e.g., 1 d, and among seasons, and that they adjust group cohesiveness flexibly depending on the food conditions and foraging tactics

コロンビア マカレナ チイキ ニ オケル クモザル ノ シャカイ セイタイガクテキ ケンキュウ : リゴウ シュウサン ノ キセツ ヘンカ ト セイサ

京都大学0048新制・課程博士博士(理学)甲第10026号理博第2687号新制||理||1365(附属図書館)UT51-2003-H447京都大学大学院理学研究科生物科学専攻(主査)教授 森 明雄, 教授 上原 重男, 助教授 大澤 秀行学位規則第4条第1項該当Doctor of ScienceKyoto UniversityDA

Embracing in a Wild Group of Yakushima Macaques (Macaca fuscata yakui) as an Example of Social Customs

ニホンザル初の社会的慣習を発見. 京都大学プレスリリース. 2015-02-10.Recently, some primatologists have begun studying social customs, which had been neglected in research despite their importance to human culture. We observed embracing behaviors 64 times during 543.8 hours of focal animal sampling, targeting adult females in a wild group of Japanese macaques in Yakushima, Japan, and compared the results with those in macaques in Kinkazan. Embracing occurred immediately after the spontaneous pause of allogrooming, aggressions, and approach between dyads frequently exchanging antagonistic interactions, all of which are considered to be stressful conditions. Embracing in Yakushima may, therefore, serve to reduce stress; this may also be the case in Kinkazan. Despite this functional similarity, the forms of embracing in Yakushima are slightly different from those in Kinkazan. First, not only ventro-ventral embraces, but also ventro-lateral and ventro-dorsal embraces were found in Yakushima. Second, kneading another’s fur by rhythmically opening and closing the palm occurred in Yakushima, instead of a rhythmic, body-rocking movement in Kinkazan. Because we cannot devise genetic or ecological explanations for the subtle local differences in embraces, this type of behavior may be identified as the first evidence for social customs in wild Japanese macaques