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.     

Temporal patterns of play bouts in captive common marmosets (Callithrix jacchus)

An objective method for defining a play bout is derived and applied to data collected from six 143–146-day old captive marmosets living in family groups. Temporal patterns within and between play bouts are investigated. There is a tendency for play bouts to occur in sessions. Play sessions are terminated by short rather than long play bouts. The pattern of components within play bouts is nonrandom. Chasing tends not to be performed either at the beginning or at the end of a play bout. Typical latencies from play bout onset to the onset of components within the bout vary from one component to another. It is argued that mechanisms controlling social play must operate at two levels: at the level of the play session, and at the level of the play bout.     

The play partners of immature baboons

In a troop of free-ranging baboons, infants played predominantly with each other, and played most with the infant of the highest-ranking female in their mothers' subgroup. The frequency of infant play appeared to be affected both by age and by the number and ages of other infants in the troop. Juveniles and subadults played more with their siblings than with other animals of their siblings' age. Juvenile and subadult females played primarily with infants, and played most with infants whose mothers ranked higher than their own. Juvenile and subadult males played most with like-sexed peers. The distribution of play partners among immatures illustrates how demographic and maturational factors, as well as those related to kinship, may reinforce or counteract one another during development.     

Social play behavior in infant Sichuan snub-nosed monkeys (Rhinopithecus roxellana) in Qinling Mountains, China

We describe the development of social play behavior and assess factors influencing the development of play in infant Sichuan snub-nosed monkeys (Rhinopithecus roxellana). Infant snub-nosed monkeys began to exhibit social play at 3 months of age, when they spent an average 0.89% of time engaging in this behavior (range: 0.7-1.12%). At 6 months of age, there was a significant increase in the proportion of time spent in social play, averaging 9.78% of observation time (range: 4.92-17.08%). However, from 7 to 9 months of age during the winter, social play decreased gradually before rising again from 10 months of age in the spring. Play behavior in infant snub-nosed monkeys is influenced by environmental temperature. Males were observed to play more than females, although further data on this are required. Social rank did not influence the social play of wild Sichuan snub-nosed monkey infants.     

Age-related Differences in Playfighting Strategies of Captive Male Red-necked Wallabies (Macropus rufogriseus banksianus)

Age-related differences in the playfighting strategy of captive male red-necked wallabies Macropus rufogriseus banksianus was examined. Our purpose was to determine whether wallabies adjusted their play in response to their partner's age and, if so, how. The way in which a wallaby played was dependent on the relative age of its partner, and this pattern tended to be the same regardless of whether it was the initiator or reactor of the interaction. If a wallaby's partner was younger than itself it adopted a defensive strategy in which it self-handicapped by standing flat-footed, Pawing rather than Sparring, and by not using its full strength. Its greater rate of Shaking suggests that this act may function as an appeasement signal in play. Furthermore, it was highly tolerant of the tactics used by its younger partner and took the more active role in prolonging interactions. If, on the other hand, its partner was older than itself, it adopted an offensive strategy involving vigorous Sparring, increased time in the High-stance posture and a greater percentage of bouts that were of high intensity. Indeed, it played with even more vigour than when it playfought with wallabies of the same age as itself. Differences in the play of same-aged partners were in the non-fighting components of play, while those of differently-aged partners were in the fighting components. Play between same-aged partners, however, tended to be more stable and more competitive than that between partners of differing age. These results are discussed with emphasis on the compromises made in order for play to occur and the potential benefits to each partner of play in mixed-age class encounters. We briefly consider the implications of self-handicapping in the categorization of macropodid fights as play or aggression.     

Playing it cool: Characterizing social play,bout termination,and candidate play signals of juvenile and infant Tibetan macaques(Macaca thibetana)

Play behaviors and signals during playful interactions with juvenile conspecifics are important for both the social and cognitive development of young animals.The social organization of a species can also influence juvenile social play. We examined the relationships among play behaviors, candidate play signals, and play bout termination in Tibetan macaques(Macaca thibetana) during juvenile and infant social play to characterize the species play style. As Tibetan macaques are despotic and live in groups with strict linear dominance hierarchies and infrequent reconciliation, we predicted that play would be at risk of misinterpretation by both the individuals engaged in the play bout and by those watching, possibly leading to injury of the players. Animals living in such societies might need to frequently and clearly signal playful intent to play partners and other group members to avoid aggressive outcomes. We gathered video data on 21 individually-identified juvenile and infant macaques(one month to five years of age)from the Valley of the Wild Monkeys, Mt. Huangshan,China. We used all-occurrence sampling to record play behaviors and candidate play signals based on an ethogram. We predicted that play groups would use multiple candidate play signals in a variety of contexts and in association with the number of audience members in proximity to the players and play bout length. In the 283 playful interactions we scored,juvenile and infant macaques used multiple body and facial candidate play signals. Our data showed that juvenile and infant Tibetan macaques use a versatile repertoire of play behaviors and signals to sustain play.     

Play in chimpanzees of the Arnhem Zoo: Self-serving compromises

In a colony of 25 chimpanzees maintained at Arnhem (The Netherlands), play behavior was studied for four months, yielding 1,651 play bouts involving the 11 oldest immature chimpanzees on which detailed data were collected during 88 focal animal samples of 30 min each. Play frequency and object play were negatively correlated with increasing age. These findings potentially reflect changing motivations during development and increasingly perfected skills. Like-aged partners were preferred play partners and older partners initiated play more frequently, probably because younger individuals feared rough responses by older immatures and waited until the latter initiated play bouts in a self-handicapped manner. Moreover, play was frequently interrupted by short breaks. This, in conjunction with the preference for like-aged partners, may be mechanisms to achieve and maintain compromises between the play partners' different interests in social play (which e.g. depend on sex and physical development) and to minimize the risk to being cheated. Males played significantly more often than females and played more chasing games. Male-male play was over-represented whereas female-female play was underrepresented. These facts potentially foreshadow sex differences in (wild) maturing chimpanzees, where males engage in more agonistic conflicts and tend to build coalitions.     

The development of different types of play in gazelles: implications for the nature and functions of play

The development of play behaviour in Cuvier's gazelle, Gazella cuvieri, is described and compared with that of other species. Play was sub-divided into four different types: locomotor play, sexual play, play-fighting and object play. Developmental trends in the types considered were different, supporting the hypothesis that play is a heterogeneous category. Locomotor play started at high frequencies, and accounted for a major proportion of total play, but both measures declined from early months onwards. By contrast, sexual play and play-fighting were infrequent shortly after birth, increased thereafter reaching peaks between 4 and 6 months, and then decreased. The relative importance of these play types steadily increased until they became the predominant types of play. Object play remained infrequent at all ages, and accounted for a small proportion of total play. Young calves played mostly alone, but the proportion of social play increased with age, until all play became social. Before month 4 calves directed more invitations to play and sexual play than they received. Other peers were the major play partners of calves, followed by adult females. Calves directed a higher proportion of invitations and sexual play to adult females and males than they received from either class. These results are discussed in relation to other aspects of the calves' behavioural and social development, and it is argued that they are best explained if play is considered to have immediate benefits.     

Changes in the rhesus mother-infant relationship through the first four months of life

Measurements of the course of interactions between rhesus monkey infants (Macaca mulatta) and their mothers during the infant's first 16 weeks showed changes in the tendencies of both partners to be together and apart. Referring only to the partner who was primarily responsible for an age-related change, by using a single index of responsibility for contact or proximity, was found to be an oversimplification. Maternal rejecting behaviour may have been primarily responsible for changes in the time spent apart only during the first 6 weeks. After the infants' sixth week, both partners' tendencies to be apart increased together. Infants then began to spend longer away partly to interact with social companions other than their mother. Mothers restricted and followed their infants more up to week 4, but after week 8 decreases in these measures allowed infants to spend longer away. Similarities between the time courses of the time spent apart from their mothers by rhesus infants in this study and in field studies are pointed out. The similarities seem striking partly because differences between studies that do not use confidence intervals (or standard errors) cannot be shown easily. Conflict between parent and infant occurred, but how it appears, and how significant it is in each species at each infant age, remains to be discovered.     

The ontogeny of social relationships with group companions among free-ranging infant rhesus monkeys I. Social networks and differentiation

Social networks of infant rhesus monkeys (Macaca mulatta) in a free-ranging, lineage-based group on Cayo Santiago are described by assessing the extent to which four measures of positive interaction between infants and finely-divided categories of companions are associated with (1) degree of relatedness through maternal lines; (2) sex of the companion; (3) age of the companion; and (4) dominance rank of the infant's lineage. The results suggest that the infant's social network mirrors that of its mother both in the first weeks of life and as late as 30 weeks of age. Infants have more positive social interaction with close kin than with distant kin or with unrelated individuals, and thus function as members of their lineage from the beginning. They associate more with female companions than with male companions, and more with younger immatures than with older immatures. Finally, infants in the top-ranking lineage spend more time with their own relatives than do infants in other lineages. The fact that these patterns change little as the infant gains independence from the mother supports suggestions that early maternal influence serves to pass on aspects of the mother's social network. It is suggested that the ontogeny of early social relationships resembles a process of differentiation.     

Play Partner Preferences in Siberian Ibex,Capra ibex sibirica

A study of social play in Siberian ibex kids at the Chicago Zoological Park revealed clear play partner preferences. Male kids played much more among themselves than with female kids and elicited more withdrawals by play partners than did ♀♀. ♂♂ and ♀♀ in mixed-sex bouts, played mostly with similarly aged partners. Male kids played a substantial amount with female yearlings; female kids did not. These differences support a motor training explanation of social play because they suggest that young ♂♂ in this sexually selected species discriminate in favor of partners with whom they can play forcefully.     

Social behavior of infant and mother Japanese Macaques (Macaca fuscata): Effects of kinship,partner sex,and infant sex

The behavioral interactions of 22 infant and mother Japanese macaques with other group members were studied. Focal-animal observations were made from the time of each infant’s birth until 1 year of age. Infants and mothers both displayed exceedingly strong preferences for associating with matrilineal kin and, specifically, for female kin. The degree of genetic relatedness was positively correlated with levels of spatial proximity, contact, grooming, aggression, and play. Overall frequencies of interactions with nonkin were very low, and partner sex was not an important factor in interactions with nonkin. There were no significant differences between male and female infants in interactions with kin versus nonkin. There was only one significant difference between male and female infants in interactions with males versus females: female infants showed stronger preferences for initiating proximity with females over males than did male infants. Because mothers provide the focal point for infant interactions during the first year of life, we compared the behavior of infants and mothers. Mothers were the recipients of more social interactions than were infants, mothers engaged in more grooming than did infants, and infants engaged in more social play than did mothers. These findings are only partially consistent with kin-selection theory, and the inadequacies of studying matrilineal kin discrimination to test kin selection are reviewed. The near-absence of infant sex differences in associations with social partners suggests that although maternal kin other than the mother are important to infant socialization, they probably do not contribute to the development of behavioral sex differences until after the first year of life.     

Social development in nursery-reared pigtailed macaques (Macaca nemestrina)

The social development of 240 nursery-reared pigtailed macaques (Macaca nemestrina) was studied from postnatal weeks 4 to 32. The objectives of the study were to document developmental trends and evaluate social behavior in laboratory-reared M. nemestrina raised at the University of Washington Infant Primate Laboratory, and to identify husbandry factors that might affect early social development. Only infants who had not undergone invasive postnatal experimental manipulation and had no chronic illness or injuries were included in the study. Infants were separated from their mothers and housed singly, but had access to peers for 30 min a day, 5 days a week, in a large playroom. Play and social behaviors emerged early in development, increased during the developmental period studied and occupied a large portion of the infants' time budgets. Although disturbance behaviors occurred with some frequency and duration early in development, they occupied a very small portion of the infants' time budget at 8 months of age. Weaning from infant formula at 16–19 weeks retarded development of play behavior. Permanent removal of a cloth comforter (diaper) during weeks 20–24 had no long-term behavioral effects. It was concluded that at 8 months of age these infants showed relatively normal species-typical behavioral repertoires. Am J Primatol 41:23–35, 1997. © 1997 Wiley-Liss, Inc.     

Pattern of play behavior in infant (age 1 to 12 months) white‐headed langurs in limestone forests,southwest China

Play behavior is a significant trait of immature nonhuman primates (hereafter primates) that plays an important role in sensory, locomotor, socio‐cognitive, and developmental processes. It has been suggested that the function of play is to practice and improve motor skills related to foraging, avoiding predators, attracting mates, raising offspring, and strengthening the skills needed for the formation and maintenance of social bonds. From September 2009 to August 2010, we investigated the play behavior of 1–12 month‐old infant white‐headed langurs (Trachypithecus leucocephalus) a Critically Endangered primate species endemic to China. We carried out this study in the Guangxi Chongzuo White‐headed Langur National Nature Reserve, and recorded 4421 play bouts and 1302 min of play engaged in by seven infants. We found that infants of different ages exhibited different patterns of play behavior. Specifically, nonsocial play behaviors appeared at one month of age, social play behaviors at two months, and an expanded repertoire of social and non‐social play behaviors at three months of age. The frequency and duration of nonsocial play peaked at five months of age and then decreased, while social play gradually increased with age. Nonsocial play did not differ between the sexes, whereas social play showed sex specificity, with a higher frequency and longer duration of social play in male infants compared to female infants. In addition, male and female white‐headed langur infants appeared to prefer individuals of same sex as social playmates, but no obvious choice preference for a specific individual. In conclusion, we provide the first report of play behavior in a population of wild Critically Endangered white‐headed langurs. We suggest that age‐ and sex‐specific differences in play behavior of infants form the bases for age and sex‐based differences in the social interactions of adult langurs.     

Social grooming and play behavior of a captive group of chimpanzees

Aspects of the social grooming and play behavior of a group of six adolescent and young adult chimpanzees are contrasted and compared. Eleven months’ data indicate that older chimpanzees groomed more and played less than younger individuals. This transition period occurred earlier for females than males. Grooming behavior appeared to vary with reproductive state. A positive correlation was found between the estrous condition of cycling females and the amount of grooming that they received from the males. A mother of a young infant received particularly high levels of grooming from the other group members. Less variation among individuals was found for frequencies of play as compared to grooming. Play dropped following the death of one individual and was entirely inhibited for three weeks following the group’s transfer to a new environment and the reintroduction of a former group member. Comparison to a free-ranging population indicates important differences in both frequencies and general patterns of play and grooming.     

The development of infant play in a captive group of lowland gorillas (Gorilla gorilla gorilla)

Three infant gorillas born at the Yerkes Regional Primate Research Center of Emory University were studied during their first year and one-half of life for various aspects of behavior, including solitary and social play, using both focal animal and one-zero sampling. The appearance of play in these infants followed a developmental trend, beginning with mother-infant play, and followed by solitary play, and then social play among peers. Mothers were initially very vigilant, repeatedly interrupting infant peer play bouts, this relaxing toward the end of the first year. Evidence for a possible sex difference in active social play is presented.     

Social behaviour of the calves of semi-wild Maremma cattle,Bos primigenius taurus

The social behaviour of semi-wild free-ranging Maremma calves, Bos primigenius taurus, was observed daily in their first 2 months from birth at the estate La Trappola (Ponticelli Reserve), 10 Km south-west of Grosseto, Tuscany, Italy. In the first 2–3 days of life the calves hid in the maquis, while the cows grazed in the surrounding area. The time spent at close range to the cows decreased with the increase in the age of the calves, but the time spent far from the mother was always greater than that spent at close or intermediate ranges. Lying down was the dominant activity at a distance over 15 m from the mother, while the time spent in standing still decreased daily. The daily mean of the minutes spent by the calves with their peers reached peaks between their 11th and 40th days of life. Sucking bouts reached a peak between 09.00 and 10.00 h, after the herd reached the grazing area from the night dormitory. Another peak occurred between 15.00 and 16.00 h. Calves solicited and terminated sucking bouts spontaneously more than cows. The mean duration of each sucking bout increased with calf age, but was negatively correlated with the mean daily number of sucking bouts. Immediately before or after a sucking bout, cows mainly sniffed their calves in the muzzle and tail area. Calves sniffed and licked the cows mainly in the area of the udder. Play activity reached a peak in the early morning, decreased strongly at mid-day and increased again in mid-afternoon. Grazing, and to a lesser extent moving to and from the pasture land, were the most frequent activities occurring before and after play. Frontal pushes were the most preferred kind of play by both females and males. Female calves soliciting play in males showed significantly more “frontal pushing” than “non-reproductive mounts”. The male calves were more often initiators of play than were females.     

The development of peer-mate relationships in Japanese macaque infants

The play behavior of Japanese macaque infants was studied for 6 months at Arashiyama, Japan. Three types of play were identified. The first (solitary play) was observed in five to 12-week old infants. The second type of play (parallel play) was observed in infants from 12 to 21 weeks old. After the 12th week, the third type of play (associate play) was seen. At this point the infants seldom played without partners. It is in associate play that dominant and submissive behavior may be seen, and from which dominance relations may be assumed. It is said that the rank of a 12 week-old infant parallels that of its mother.     

Activity profile of young soccer players during actual match play

This study investigated the activity profile of young soccer players (mean age 11.8 +/- 0.6 years; N = 12) with the aim of providing information for the development of training strategies. Data for movements of each player were obtained using 2 cameras that aimed at the subject throughout the match (Play Controller, Phromos, Italy). Encoders transmitted camera movements to a computer. The collected signals were then converted into distances, times, and speed attained at arbitrarily selected match categories. Players were monitored during official 11 vs. 11 matches (N = 12), with each match consisting of 2 halves, each lasting 30 minutes played on a regular soccer pitch. Mean total match distance amounted to 6,175 +/- 318 m. During the second half, players covered 5.5% less distance (p > 0.05). At speeds between 13.1 and 18.0 km.h(-1), players covered 12% less distance during the second half (p < 0.05). Players stood still 11% of the total time played (3,789 +/- 109 seconds). At speeds faster than 18 km.h(-1), players performed 33 +/- 4 bouts during match play, with a mean time length of 2.3 +/- 0.6 seconds per bout. Mean time interval between two successive maximal sprint bouts was 118.5 +/- 20.5 seconds. Players stood still longer during the course of the second half (229 +/- 76 seconds vs. 173 +/- 61 seconds, p < 0.05). Players tended to play in small areas of the football pitch and spent 9% of the total match time at high intensity. In order to promote a more active space coverage of the young player, at least for the age considered in the present study, the dimensions of the football pitch and the number of players should be reduced.     

Social relations in a free-ranging troop of stumptail macaques (Macaca arctoides): Male-care behaviour I

The occurrence of male-care behaviour directed from juvenile and adult males to infants was studied in a free-ranging troop of Stumptail macaques. The study period lasted two months comprising about 140 hours of recorded observations. Infants were a focal subgroup and their interactions with older males were recorded. The following variables were examined in relationship to the sending and receiving of male-care: the infant (its age, sex, and dominance rank), older males (their age and dominance rank), and genetic ties. Infants I received more male-care than infants II and differences in the type of male-care received by infants I and II were found. Male infants received more male-care than female infants and sex differences in the type of care received were evident. No relationship was found between the infant’s dominance rank and the amount of male-care received. A substantial amount of male-care behaviour was sent to genetic kin. Two-three year olds displayed more male care than yearlings. Juveniles as a class displayed more male-care than adults. A positive association was found between the juveniles’ dominance rank and the sending of male-care. However, among the adults, the subordinate male displayed more care behaviour than the alpha male. The presence or absence of the mother was found to influence the older males’ interest in the infant. The results are discussed and compared with data available on other primate species. Supported by grants from the Behavioral Science Foundation (U.S.) and by the Mexican Institute of Anthropology.