On dominance rank and kinship of a wild Japanese monkey troop in Arashiyama

Observations on dominance rank and kinship of a wild Japanese monkey troop living in Arashiyama, Kyoto, were made as follows: (1) Ranking exists among consanguineous-relatives, and their dominance relation has a great effect on the ranking of individual infants, the influence of which remains after they have grown; (2) With the development of individual infants, a dominance rank is formed by the age of 1 among males and females of the same age according to the ranking of their mothers in the troop, that is, the ranking of consanguineous-relatives, and it remains unchanged through the age of 2; (3) Comparison between individual males and females in ranking becomes difficult to assess after about 3 years of age, though the dominance rank based on mothers' rank still exists among both males and females of the same age. And this dominance' rank becomes very stable; (4) The principle of “youngest ascendency” becomes effective among sisters more than 4 years old. The youngest sister ranks just below her mother and holds the second rank among lineal consanguineous-relatives; (5) Brothers of very close ages temporarily tend toward youngest ascendency when they are 2 or 3 years old, but this relation is soon reversed into the dominance of the elder brother over the younger; (6) Whether male or female, a younger infant of a higher-ranking mother challenges an elder one of a lower-ranking mother and outranks it. In the case of males especially, disparity of age, joint effects of a group, dependent effects on the central part that attend on peripheralization play an important role in outranking.     

Changes of dominance rank,age, and tenure of wild Japanese macaque males in the Kinkazan a troop during seven years

Male age-rank and tenure-rank relationships were studied for seven years in unprovisioned Japanese macaque (Macaca fuscata fuscata) troop on Kinkazan Island, Japan. Males whose estimated ages were between 15 and 19 yr old monopolized the highest ranks, while older males whose estimated ages were ≥ 20 yr old tended to decline in rank, resulting in a humped age-rank curve. The ranks of males tended to rise as their tenure in the troop increased. The departure of higher-ranking males was the social mechanism for changes in rank, suggesting that the disappearance of higher-ranking males plays an important role in determining rank dominance.     

The daily activity rhythm in a troop of wild Japanese monkey

An assessment of the daily activity rhythm of wild Japanese monkeys was tried both from the calculation of the proportion that each activity occupied in the total activities and the “nomadograph,” representing temporary change in the pace of the daily movement. Seasonal and day-to-day changes are recognized in the daily activity rhythm of the troop of wild Japanese monkeys. It seems that seasonal change in the daily activity rhythm corresponds to the seasonal fluctuation of food supply and atmospheric temperature. From autumn to early winter, when much food is available, a clear-cut pattern of activity emerges; namely, three intensive feeding periods are recognized in a day. Moreover, day-to-day variation in the activity rhythm is fairly small and the activity pattern thus becomes standardized. In winter, when least food is available, activity of monkeys drops to the lowest level of the year. Day-to-day variation in the activity rhythm is great. Two to four intensive feeding periods in a day are recognized. In early spring and summer, when food supply is rather scarce, there exist two to three intensive feeding periods in a day. During the heat of the day in summer, activity of monkeys is conspicuously low.     

Mirror responses in a Japanese macaque troop (Arashiyama West)

Behavior toward two mirrors in the field was observed in the Arashiyama West troop ofMacaca fuscata. Counts of visits to the mirrors, plus scan and focal animal sampling were used. Some animals were marked with fluorescent paint to test informally for self-recognition. A relatively high mean frequency of visits to the reflecting side of both mirrors by all age classes, ranks, and sexes was recorded. There was no age difference in frequency of mirror visits per sample but adults spent more time per visit than subadults who in turn spent more time than juveniles. There was no indication of self-recognition by paint-marked animals. Mirrors appeared to be used to monitor the reflected scene and to look at the self-image. Social behavior in the mirror zone that was not directed toward the mirror was common to all age classes. Species-typical behavior directed toward the mirror was seen in younger animals but very seldom in adults. No threat displays by any animal were observed. We suggest that for adults the mirror image was not seen simply as another monkey.     

Agonistic behavior in a transplanted troop of Japanese macaques: Arashiyama west

Arashiyama A troop was transplanted from Japan to Texas, U.S.A. in February 1972 and released into a large outdoor enclosure (42 ha) in a semi-free ranging condition. Agonistic behavior was quantified during the first six months after the release. Agonistic interactions occurred at about one incident per 100 monkeys every 2 to 9 minutes. In general, peaks in frequency of agonistic interactions coincided with peaks in feeding activity. 97.5% of all incidents were of a “mild” type, and 85.7% were simple one-to-one, unidirectional interactions. “Severe” forms of agonistic behavior occurred only during the first month and then only rarely. Adult females and juveniles were initiators in about 93% of all cases. In general, the more severe the form of attack, the more pronounced was the form of submission.     

Food adaptations of a transplanted Japanese macaque troop (Arashiyama West)

In 1972 Arashiyama West troop of Japanese macaques was transplanted to southcentral United States and kept in semi-free ranging conditions. The new environment provided an opportunity to assess aspects of the species' adaptive potential. About 1,500 feeding observations were made monthly over 6.5 months. Unlimited provisioned food was available, but monkeys utilized native plants immediately and use increased until it included 50+ % of the diet by weight. Shrubs provided 75% of foods in first month and 32% thereafter. Sorghum comprised 25% in May–July. Soil, arthropods, fungi, bulbs, and roots each comprised less 5%. Between 21 and 37 foods were utilized monthly. Monthly food uses corresponded to availability. Many food plants required unique handling by monkeys. Four general adaptive responses to potential foods are described. Evolution has clearly shaped the Japanese macaque into a highly omnivorous and behaviorally flexible animal.     

Interindividual distance and influence of dominance on feeding in a natural Japanese macaque troop

In a natural troop of Japanese macaques (Macaca fuscata yakui), the dominant-subordinate relationship restricted the feeding behavior of the subordinate in two ways: (1) the dominant drives away the subordinate through agonistic interactions; and (2) the subordinate avoids approaching the dominant without any agonistic interactions. These occurred only infrequently, and only when an interindividual distance was less than a certain distance, which is called the “tolerance/intolerance” (T/I) distance. On the other hand, the usual interindividual distance when feeding was much greater than the T/I distance. Therefore dominance has little influence on feeding in the study troop. In the study troop, the T/I distance between kin-related females was shorter than that between unrelated individuals. Although this difference may facilitate kin selection if the troop faces severe competition over concentrated food, the difference does not seem to influence survival or reproductive rate in the study troop.     

Some spacing relations among the central males of a transplanted troop of Japanese macaques (Arashiyama west)

In February, 1972, a troop of 150 Japanese macaques was tranplanted from Kyoto, Japan, to Laredo, Texas, USA, after 20 years of study in Japan. As part of the general adaptation of the troop to its new environment, spacing behavior was observed in the central adult males [by independent rank, (1)Dai, (2)W, (3)Bus 62, and (4)Kojiwa 59]. Spot checks of locations, vertical space use, mobility patterns, and paths to and from a box of apples suggested that the major influences on spacing were rank, personality and history, social interactions, and several environmental factors (availability of vertical space, water, and shade, extreme heat, daily provisioning, etc).Dai exceeded the other males in use of vertical space, rate and distance of travel, and proximity to the apple box.W confined his high use of vertical space use primarily to one structure. His distance and rate of travel were low, and he maintained the greatest distance from the apple box.Bus 62 ranked second in use of vertical space, distance and rate of travel, and proximity to the apple box.Kojiwa 59 frequently changed sites in his use of vertical space. His distance and rate of travel were low, and he maintained long distances from the apple box.     

Male life history in natural populations of Japanese macaques: Migration, dominance rank, and troop participation of males in two habitats

This paper compares male life history parameters of two populations of Japanese macaques (Macaca fuscata Blyth, 1875), studied without provisioning: Yakushima (M. f. yakui), a subtropical forest habitat in southwestern Japan, and Kinkazan (M. f. fuscata), a temperate, deciduous forest habitat in northeastern Japan. The males of the two sites experienced similar life histories with respect to several traits. Age at natal dispersal was at about 5 years. Average troop residence was about three years. Most males joined troops at the bottom of the rank order, although a few males joined troops at the top rank. Dominance ranks of males tended to rise with the death or departure of higher ranking males. Visiting males accounted for about 41% of observed mating at both sites. However, the two sites differed in the sex ratio of troops, partly because a larger proportion of males apparently lived outside of troops in the Kinkazan site compared to Yakushima. In particular, non-natal young males were absent from the main study troop at Kinkazan. Large within-species variation may exist in the degree to which males associate with troops.     

Playmate relationships among individuals of the Japanese monkey troop in arashiyama

Observations of play behavior were made on a troop of Japanese monkeys for five months. The troop consisted of 125 animals during the study period. Only 104 animals were observed playing with the troop members while the other 21 animals were never observed playing with other individuals. Two-member play was the most frequent. On the average, a monkey played with 20.7 individuals. A total of 6,068 play bouts were observed. The frequency of play appeared to be affected by age, sex, and degree of relatedness. One-year-old infant males played most with other members and the frequency of play decreased with age. Between monkeys whose disparity of age was less than two years, 5,763 bouts (95.0% of the total) were observed. Moreover, among sameaged monkeys who comprised 10.6% of the possible pair combinations, 2,739 play bouts (45.1%) were observed. Juvenile males played with same-sexed peers more than with opposite-sexed peers, whereas older juvenile females appeared to play with infants of both sexes. Individuals who were related and similarly-ranked tended to play together. There was no apparent preference for animals to play with the offspring of the highest-ranking female. Dominance rank of infnats and juveniles was primarily affected by rank of their mothers and to a lesser extent by play partners. Dominance rank of older juvenile males is more likely to be affected by play partners than females. It may be a critical time for males when they leave their natal troop and join a new troop. The timing of troop shifting by males seemed to be affected by the presence or absence of play-mates. For male Japanese monkeys, play is very important in developing social bonds. Play may act to perpetuate social bonds, enhance the chance of survival, and may contribute to their future reproductive success.     

Behavioral patterns of estrous females of the Arashiyama West troop of Japanese macaques (Macaca fuscata)

This report contains detailed data on the sexual behavior of the 60 sexually mature females of the Arashiyama West troop of Japanese macaques. The study group was a natural troop transported intact in 1972 to a ranch in South Texas. Since transplantation, the monkeys have been free to roam and feed within a 42.2 ha enclosure. Analysis of data collected on the 140 monkeys that composed the troop during the 1973–74 and 1974–75 breeding seasons revealed: (1) Female-male mounting is an important aspect of Japanese macaque sexual behavior; (2) All females had preferred partners and most avoided both heterosexual and homosexual interactions with close kin; (3) Pubescent and adult females exhibit different patterns of sexual behavior; (4) Pubescent and adult females were affected somewhat differently by the transportation from Japan to their current home in South Texas. These behavioral patterns and their implications are discussed. The study was partially supported by PHS Biomedical Science Grant 50-262-1112.     

Comparative study of grooming relationships among wild Japanese macaques in Kinkazan A troop and Yakushima M troop

The influences of socionomic sex ratio (SSR; adult males/adult female) and troop size upon male-male, female-female, and male-female grooming relationships were examined and compared between two wild Japanese macaque troops (Kinkazan A and Yakushima M troops) in Japan. The Yakushima M troop was smaller and had a higher-SSR than the Kinkazan A troop. Between the troops, (1) the male-male grooming frequency and number of partners were greater in the Yakushima M troop than in the Kinkazan A troop; (2) the female-female grooming frequency and number of partners were not different; and (3) the male-female grooming frequency and number of partners were not different. Based on these features, the patterns of female-female and male-female grooming relationships appear to be independent of SSR and troop size variations. In contrast, male-male grooming relationships are influenced by both factors, especially SSR. Frequent grooming interactions among males may be useful for the continued coexistence of relatively many males especially in a higher-SSR troop.     

Inter-male associations in a wild Japanese macaque troop on Yakushima Island,Japan

Adult male association and its annual change were studied in a wild population of Japanese macaques (Macaca fuscata yakui) on Yakushima Island, Japan. Unlike many other Japanese macaque troops, adult troop males frequently maintained proximity and exchanged grooming with one another in both the mating and non-mating seasons, and the dominance relationship rarely appeared in such inter-male associations. The few cases of agonistic interactions occurred mostly when estrous females or food resources were immediately concerned. Although troop males were very intolerant to newly appeared solitary males (new males) during the mating season, close associations were formed between troop males and new males as soon as the mating season terminated. The consort of new males and lower-ranking troop males with estrous females was frequently disturbed, but these males could copulate no less frequently than higher-ranking males. A comparison among macaque species suggests the existence of two forms of inter-male association: (1) the frequent association based on the symmetrical exchange of social behaviors; and (2) the infrequent and asymmetrical association related to the dominance relationship. The form of inter-male association seems to be influenced by whether or not males can keep close associations with females throughout the year.     

Initiation and solicitation in male-female grooming in a wild Japanese macaque troop on yakushima island

Grooming initiation among adult males and females of a Japanese macaque troop was analyzed during the non-mating season. Some gestures (“solicitation”) elicited grooming from partners at a high rate. Grooming initiation patterns were divided into two main types: (1) a male often solicited a female to groom him immediately after approaching her and was groomed by her; and (2) a female approached an alpha male selectively, and immediately groomed him. After a female groomed a male, she rarely solicited him to groom her and instead often moved away from him. These results indicated that males were motivated to be groomed, while females were more highly motivated to groom. Sex differences in grooming motivation can be explained by sex differences in the benefit to be groomed.     

A description of genealogical rank changes in a troop of Japanese monkeys (Macaca fuscata)

Rank changes among females of a troop of 154 Japanese monkeys (Macaca fuscata) are described. A medium ranking female, with support from the alpha male, successfully challenged the alpha female. Following this dominance shift, almost all members of the two genealogical groups underwent rank changes. The observations provide some evidence that the role of alpha female may be competed for, just as the alpha male position is, in macaque social groups.     

A new approach to evaluating troop deployment in wild Japanese Monkeys

In winter when the mountain slopes are covered with deep snow, it is easy to obtain quantitative data on the two-dimensional deployment of members of a troop of wild Japanese monkeys. We observed the deployment of a troop on a slope from the opposite side of a river. The deployment patterns, evaluated on the basis of the relative distance from the central point (centroid) of the troop, were different for each sex and age category. Adult females, infants, and 1-year-olds tended to be grouped together and were concentrated near the center of the troop. On the other hand, adult males were randomly spaced. These tendencies suggest that the deployment reflects the social structure of the duplicate concentric-circle model originally proposed by J. Itani (1954).