Affiliative interactions between one-male units in a band of Sichuan snub-nosed monkeys (Rhinopithecus roxellana) living in the Qinling Mountains, China.

We studied affiliative behaviors that occurred within and between one-male units (OMUs) in a band of Sichuan snub-nosed monkeys (Rhinopithecus roxellana) living in the Qinling Mountains, China for 3 years from 2002 to 2004. During the birth season, females handling infants of other females affiliatively interacted with females in neighboring OMUs as well as with females in their own OMU. After these interactions, affiliative encounters occurred without conflict between the OMUs. In the mating season, females sometimes presented their genitals to males of other OMUs. These interactions may facilitate the maintenance of a higher level social organization, a band. Therefore, the band composed of OMUs and all male group(s) is the basic unit of social structure of this species. Almost all other Asian colobines have OMUs that either maintain distance from each other or engage in territorial defense, so these OMUs would not be expected to form a band. Contrary to these species, the 3 species of Rhinopithecus spp. inhabiting China form a band composed of OMUs, because infants and females may function as a bridge connecting OMUs.

Shape of, and body direction in, huddles of Japanese macaques (Macaca fuscata) in Arashiyama, Japan.

We studied huddles of Japanese macaques (Macaca fuscata) in the Arashiyama E troop at the "Arashiyama Monkey Park, Iwatayama" of Kyoto, central Japan. The macaques made physical contact with other individuals and formed huddles when the air was cold. The 99-101 adult females and 26-36 adult males in the study troop formed 345 huddles during 42 scan samples in the winter of 2001 and 376 huddles during 52 scan samples in the winter of 2002. The average size of huddles was 2.3 (range 2-7) individuals. Males huddled less frequently than females. Maternal kin-related dyads formed 2-female huddles more frequently than unrelated dyads. Choice of huddling partners might restrict the size of huddles. The most frequently observed 3 and 4-member huddles were triangular and diamond-shaped. Macaques usually huddled ventro-ventrally, ventro-laterally, and ventro-dorsally. A third individual frequently placed the ventral part of its body against the first individual and simultaneously put the lateral part of its body against the second individual, so that the 3 individuals formed a triangular huddle. This behaviour indicates that Japanese macaques choose their position and body direction in the huddle to reduce the area of body surface exposed to the air, thereby conserving body heat.

Dietary adaptations of temperate primates: comparisons of Japanese and Barbary macaques.

Habitat, diet and leaf chemistry are compared between Japanese and Barbary macaques to reveal the similarities and differences in dietary adaptations of temperate primates living at the eastern and western extremes of the genus Macaca. Tree species diversity and proportion of fleshy-fruited species are much higher in Japan than in North Africa. Both species spend considerable annual feeding time on leaves. Japanese macaques prefer fruits and seeds over leaves, and Barbary macaques prefer seeds. These characteristics are adaptive in temperate regions where fruit availability varies considerably with season, since animals can survive during the lean period by relying on leaf and other vegetative foods. The two species are different with respect to the higher consumption of herbs by Barbary macaques, and the leaves consumed contain high condensed and hydrolysable tannin for Barbary but not for Japanese macaques. Barbary macaques supplement less diverse tree foods with herbs. Because of the low species diversity and high tannin content of the dominant tree species, Barbary macaques may have developed the capacity to cope with tannin. This supports the idea that digestion of leaves is indispensable to survive in temperate regions where fruit and seed foods are not available for a prolonged period during each year.

The influence of snowfall, temperature and social relationships on sleeping clusters of Japanese monkeys during winter in Shiga Heights.

We studied Japanese monkeys (Macaca fuscata) of the Shiga A(1) troop at their sleeping sites in Shiga Heights, Japan, for 41 nights during 3 winters. Monkeys chose their sleeping sites in Japanese cedars and in deciduous broad-leaved forests on non-snowing nights and in Japanese cedar forests on snowing nights. We counted 399 sleeping clusters in which 2 or more monkeys remained in physical contact through the night and 43 solitary sleeping monkeys, though monkeys did not maintain physical contact with others in the daytime. We found 397 clusters on tree branches and 2 clusters on rocks. The mean size of huddling clusters was 3.06+/-1.22 SD. The cluster size (3.17+/-1.26 SD) at lower ambient temperatures between -7 and -4 degrees C was larger than that at higher temperatures between -2 and 4 degrees C (cluster size 2.88+/-1.13 SD). Most clusters were composed of kin. Females kept close to related females in the daytime and huddled with them at night. The highest-ranking male mainly huddled with his kin and his familiar females. Other males kept farther apart from each other in the daytime, probably to avoid social conflicts. Through cold winter nights, however, such males reduced inter-individual distances and huddled with other males. Japanese monkeys appear to recognize three types of inter-individual distances: an intimate distance less than 1 m, a personal distance of 1-3 m and a social distance of 3-20 m; they change their inter-individual distances according to social and ecological circumstances.

The distribution pattern of rhesus and Assamese monkeys in Nepal.

Surveys of the distribution and some ecological characteristics of rhesus monkeys (Macaca mulatta) and Assamese monkeys (M. assamensis) in Nepal were conducted during 234 days in 1976, 1978, and 1984. Rhesus monkeys dominated in the tropical, subtropical, and temperate forests below 3,000 m a.s.l. all over Nepal. Assamese monkeys were patchily distributed along rivers in the tropical and subtropical areas. Both species principally utilized forests parapatrically. The mean troop size of rhesus monkeys (29.5) was significantly larger than that of Assamese monkeys (19.1). Discontinuous distribution of Assamese monkeys probably appeared as a result of the expansion of rhesus monkey distribution in the mid- and late-Pleistocene. Because of small distribution areas and small numbers of monkeys, urgent conservation policy must be pursued.