Is lipsmacking an indicator of social status in baboons?

Lipsmacking is performed by many Old World monkey species, and some studies of baboons and macaques suggest that lipsmacking may be associated with social status. We studied 60 adult anubis baboons (Papio cynocephalus anubis) for 18 months, measured social status and the rate of lipsmacking, and used these data to test the hypothesis that lipsmacking is related to social status. Our results indicate that social status and lipsmacking were not significantly correlated for either males or females. Analysis of lipsmacking in relation to social class (high vs. low) showed no significant difference between status classes for either sex. Lipsmacking was, however, found to be positively associated with affinitive behaviors. These results suggest that baboon lipsmacking provides positive social communication independently of social status.     

Giant chacoan peccary: Feeding and social behavior of a captive group in natural habitat

Social behavior of the giant Chacoan peccary, also known as the taguá, is relatively unknown due to the harsh environment and endangered status of the population. In order to characterize feeding and social behaviors, a group of 7 adults, 2 juveniles, and 3 infants was observed in their feeding area for 99.25 hours over 18 days during October and November 1989. All animals were housed in a 2 ha natural-habitat enclosure in the Chaco of Paraguay. It was determined that these peccaries fed in intervals throughout daylight hours and that juveniles spent more time per approach in the feeding area than adult males. It was also observed that infants were accepted and well tolerated by the entire group, including adult males. These observations have relevance to taguá behavior in the wild and provide new insights into social patterns of this recently discovered species.     

Sex and age differences in juvenile social priorities in female philopatric,nondespotic blue monkeys

Juveniles should choose social partners on the basis of both current and future utility. Where one sex is philopatric, one expects members of that sex to develop greater and sex‐typical social integration with group‐mates over the juvenile period. Where a partner's position in a dominance hierarchy is not associated with services it can provide, one would not expect juveniles to choose partners based on rank, nor sex differences in rank‐based preferences. We tested these ideas on 39 wild juvenile (3.2–7.4 years) blue monkeys (Cercopithecus mitis stuhlmanni), cercopithecines with strict female philopatry and muted hierarchies. We made focal animal observations over 6 months, and computed observed:expected amounts of proximity time, approaches and grooming given to various social partners. Overall, our results agree with the hypothesis that juvenile blue monkeys target social partners strategically. Spatial proximity, approaches and active grooming showed similar patterns regarding juvenile social preferences. Females were far more sociable than males, groomed more partners, reciprocated grooming more frequently, and preferred—while males avoided—infants as partners. Older juveniles (5–7 years) spent more time than younger juveniles (3–4 years) near others, and older females were especially attracted to infants. Close kin, especially mothers and less consistently adult sisters, were attractive to both male and female juveniles, regardless of age. Both sexes also preferred same‐sex juveniles as social partners while avoiding opposite‐sex peers. Juveniles of both sexes and ages generally neither preferred nor avoided nonmaternal adult females, but all juveniles avoided adult males. Partner's rank had no consistent effect on juveniles' preference, as expected for a species in which dominance plays a weak role. Juveniles' social preferences likely reflect both future and current benefits, including having tolerant adult kin to protect them against predators and conspecifics, same‐sex play partners, and, for females, infants on which to practice mothering skills. Am. J. Primatol. 72:193–205, 2010. © 2009 Wiley‐Liss, Inc.     

Affiliative relationships between adult males and immature group members in naturally occurring ringtailed lemurs (Lemur catta)

Affiliative relations between adult males and immature group members were studied in three naturally occurring groups of ringtailed lemurs (Lemur catta) over a 12-month period at Beza-Mahafaly Reserve, southwestern Madagascar. No statistically significant difference was found in rates of affiliative interactions between adult males and older immatures (juveniles and adolescents) over reproductive seasons. However, some of the adult males in two focal groups increased their rates of affiliative behaviors with older immatures during the lactation and subsequent 1993 postmigration periods. Female involvement with infants during lactation season, the increasing independence of juveniles and adolescents, and length of male tenure may be factors contributing to such a pattern. Neither adult males nor immatures were significantly responsible for the initiation and maintenance of proximity in male-immature dyadic interactions. Neither dominance rank nor age-class of the adult male affected their rates of affiliative behavior with immatures. The majority of focal males exhibited an interest in infants and occasionally participated in alloparental care. It is suggested that adult males can benefit from affiliative relations with immatures in terms of opportunities for greater spatial centrality in the group, which can lead to enhanced predator protection and greater opportunities to develop affiliative relationships with females. Immatures can benefit from affiliation with males in relation to enhanced predator detection and protection, alloparental care, and opportunities to develop social skills. Am J Phys Anthropol 103:163–171, 1997. © 1997 Wiley-Liss, Inc.     

Activity and ranging patterns of Colombian woolly monkeys in north-western Amazonia

In this study, I revise three aspects of the socioecology of woolly monkeys (genus Lagothrix) that might give us a better understanding of the patterns found in this species: (1) the association between temporal variation in fruit abundance and diet, activity, and ranging patterns; (2) the individual trade-offs associated with living in small or large groups, and (3) the relationship between social dominance and foraging success. Using behavioral and ecological data collected during 3 years in Tinigua Park, Colombia, I found that woolly monkeys tend to avoid open-degraded forests, where fruit production is generally lower than it is in mature forests. Diet and activity budgets were highly associated with temporal patterns of fruit production. Daily path length was positively correlated with group size and monthly fruit abundance, and negatively correlated with habitat quality. I found differences in activity budgets and the diet preferences of different age/sex classes. For example, adult males rest more and juveniles play more than other classes. Juveniles and adult females without infants look for arthropods more often than adult males and females with young infants, who showed the highest frequencies of fruit feeding. Dominant adult males were not consistently the most efficient foragers on fruits according to two different indexes. Most of these results are consistent with the expectations from strong intra-group competition for resources. However, females with infants received benefits during feeding similar to those of dominant adult males, which may be mediated by differential aggression from males to other group members (juveniles and females without infants).     

Origin and fate of a one-male savanna babbon group formed by fissioning

An adult male chacma baboon,Papio hamadryas ursinus, emigrated from his habituated natal group at age 100 months and joined a neighboring multimale-multifemale group. Subsequently this male, together with eight adult females, all with infants <1 year old, formed a one-male group (OMU). The male was the only adult male in this group for over 200 days. Circumstantial evidence shows that shared parentage of the infants with this male determined which females joined the new group. In addition, 10 juveniles younger than 4.5 years joined the new group. Based upon persistent close physical association, especially at sleeping sites, these juveniles were presumed to be the older independent progeny of the eight adult females. Thus, the founding elements of the new group were the adult male and partial matrilines—mothers, their infants, and their independent juvenile offspring. The OMU status of the group ended with the sequential intrusion of three males known to be low ranking in other groups. The first of these intruders was successful in joining the OMU in spite of the OMU male's earlier successes in rebuffing this and other potentially high-ranking males. Six additional males later entered the fission group during a 6-month interval. Two of them outranked the original male. All additional males present in the last 100 days of observations came from the same group, which was not the group of origin of the females.     

The ontogeny of sex differences in the behavior of patas monkeys

Many studies of sex differences in primates have been based on small experimental groups of peers in which only a limited range of social behavior could be expressed. In addition, the first few months of life are often the focus of such studies, with relatively little attention paid to older juveniles. In this study, 11 male and 9 female juvenile patas monkeys, living in a captive social group with all age-sex classes available, were observed between 1 and 4 years of age. A subset of seven patas monkeys was also observed between birth and 1 year of age. Here, we report the development of sex differences in independence, play, grooming, positioning behavior, and aggression over the juvenile period. Juvenile male patas monkeys played more and in longer bouts than females, but wrestling (rough-and-tumble play) was not more common among males. There were few differences in behaviors directed to male and female juveniles by other group members. Distinct differences emerged only in the behaviors of the juveniles themselves, with females being more active participants in social and aggressive interactions than males. In general, sex differences in patas monkeys show a mixture of patterns, some of which are predictive of adult sex differences and some of which appear to be specific to the particular demands of the juvenile period in this species     

Lactation and care for unrelated infants in forest-living ringtailed Lemurs

An adult female ringtailed lemur (Lemur catta) known not to have been pregnant showed spontaneous lactation in response to twin infants born to an unrelated female. The females had met only 7 months earlier, when they and two other unrelated adult females were released from separate locations in a forest enclosure to form a new social group. Three months after release, an adult male from an adjacent enclosure gained access to the new group for 1 day, the day of one female's estrus. No males had access to the females throughout the remainder of the breeding season. Within 2 weeks of the birth of the twins, one of the other adult females began carrying the infants frequently, typically one at a time. All three females were checked for lactation when the infants were two months old. Both their mother and the unrelated adult who had been carrying the infants were producing milk. The third adult female, who never carried either infant, had no milk. The third adult female, who never carried either infant, had no milk. This female, however, like the two maternal females, frequently attacked unfamiliar immigrating adult males when the males approached the infants. Potential implications of these observations concerning the social organization of ringtailed lemurs are discussed.     

Social organization of white‐headed langurs (Trachypithecus leucocephalus) in the Nongguan Karst Hills,Guangxi, China

The number of males per group is the most variable aspect of primate social organization and is often related to the monopolizability of females, which is mainly determined by the number of females per group and their reproductive synchrony. Colobines show both inter‐specific and intra‐specific variations in the number of males per group. Compared with other colobine species, little is known about the social organization of white‐headed langur (Trachypithecus leucocephalus), despite its endangered status and unusual limestone habitat. As a part of a long‐term study of the white‐headed langurs in the Nongguan Karst Hills, Guangxi, China, we quantitatively investigated their social organization by analyzing census data from 1998 to 2003. The population censuses revealed that the predominant social organization of bisexual groups was the one‐male group, similar to a previous report on this species and many other Asian colobines. In such groups, one adult male associated with 5.1 adult females, 0.1 sub‐adult males, 2.6 juveniles and 2.9 infants on average, with a mean group size of 11.7 individuals. In addition, three multi‐male groups were recorded, consisting of 2–3 adult males, 1–5 adult females, 0–2 sub‐adult males, 0–7 juveniles and 0–2 infants. They did not contain more adult females than the one‐male groups and were unstable in group membership. The langurs outside bisexual groups were organized into small nonreproductive groups or lived as solitaries. The nonreproductive groups averaged 1.3 adult males, 1.3 sub‐adult males and 2.6 juveniles. Juvenile females were present in such groups on 52.4% of all occasions. As predicted by the monopolization model, the prevalence of the one‐male pattern in this species may mainly be attributed to the small number of females in the group. The possible reasons for the occurrence of multi‐male groups and the presence of juvenile females in nonreproductive groups are also discussed. Am. J. Primatol. 71:206–213, 2009. © 2008 Wiley‐Liss, Inc.     

Changes in social interactions during adolescence in male mandrills (Mandrillus sphinx)

The adolescent period in male mandrills extends from the time the testicles descend (at the age of 3-4 years) to the time adult characteristics develop (at the age of 10 years), and is thus one of the longest adolescent periods in cercopithecines. In this short cross-sectional study of 11 male mandrills (4.7-9.1 years old), we analyzed social behavioral patterns to investigate partner preference and changes in types of interactions throughout puberty. The mandrills were separated into two clusters on the basis of all of the social interactions scored, as well as the age and sex of the protagonist. During early to mid puberty, immature individuals interacted preferentially with other male adolescents and juveniles. Playing was an important activity, and some affiliative interactions with juveniles were observed. Older adolescents interacted more with adult males and females. These older adolescents were predominantly aggressive toward other adolescents, females, and juveniles, and showed little or no affiliative or playful behaviors. These results indicate a shift in social partners: older males interacted more frequently with adult males, and their behavior involved more aggression and less submission compared to younger adolescents, which showed predominantly submissive and playful behavior. These changes are consistent with preparation for dispersal and future intermale competition.     

Infanticide and juvenilicide in Hanuman langurs (Presbytis entellus) around Jodhpur,India

Ten cases of infant killings and 2 cases of juvenile killings were observed in two troops of Hanuman langurs, (Presbytis entellus) around Jodhpur, India. Fatal attacks on infants and juveniles are classified into four categories. The process of infanticide was observed from start to end and is described in detail for 3 cases. The age of the victims ranged from 0.2 to 48 months. The interbirth interval among females whose infants were killed is significantly shorter compared to females whose infants survived. In ourt study, 7 cases support the reproductive advantage hypothesis, that infanticide is an adaptive behaviour to increase male reproductive success. The remaining 5 cases do not fit into the reproductive advantage hypothesis. In these cases, victims are over 8 months old, and as such their deaths could not shorten the interbirth interval. It appears that by killing older infants and juveniles the males obtain an advantage in resource competition for their offspring. An alternative is that new males chase or peripheralise the older infants and juveniles, which leads to 97% predominant uni-male troop structure in Jodhpur.     

Social and solitary play in a colony of vervet monkeys (Cercopithecus aethiops)

This study describes and defines play in a laboratory colony of vervet monkeys (Cercopithecus aethiops). Play is divided into 26 units of behavior and the frequencies of these behaviors are recorded. Analysis shows that sex, age, and dominance have effects on some play behaviors. The play behavior of each age/sex group within the colony is described both quantitatively and qualitatively. Adult females are characterized by reinforcement of the play of immature monkeys, adult males by rough play with older male juveniles, four-year-old females and three-year-old males by stimulation of play in young infants, and males in general by a preference to play within their peer group. It is suggested that modified repetition of behaviors, diversified interactions, and innovative behaviors, are important qualities of play, and are essential to the adaptive plasticity of behavior in primates.     

Behavior of nursery/peer-reared and mother-reared rhesus monkeys from birth through 2 years of age

The behavior of 8 nursery/peer-reared and 16 mother-only reared rhesus macaques was observed between birth and 5 months of age, with follow-up studies conducted when the animals were 10–21 months old and living in large social groups. Nursery-reared neonates were more awake, active, and irritable than mother-only reared monkeys. From 1 to 5 months of age the nursery/peer-reared animals exhibited a greater variety of behaviors than the mother-only reared infants, which spent the majority of the time in ventral contact with mothers. As juveniles the groups were indistinguishable with the exception of more self-directed behaviors observed in the nursery/peer-reared monkeys. Both rearing conditions, by virtue of their atypicality, imposed restrictions on social development. The behavioral similarity of the juveniles while in the large social group may be a function of maturation or due to the rehabilitative effect of the large social group.     

Social influences on the development of foraging behavior in free-living common marmosets (Callithrix jacchus)

In this study we investigated the extent and pattern of social influences (i.e., the use of a conspecific as a model) on the foraging behavior of immature, wild common marmosets (Callithrix jacchus) as a function of the age of individuals. We compared the foraging activities and interactions with subadult and adult group members (older than 15 months) of young infants (1-2 months old), older infants (3-4 months old), and juveniles (5-10 months old). In addition to measuring the intensities of model-independent foraging (MIF) and merely paying attention to the model's foraging activities, we examined the frequencies of three types of model-dependent foraging (MDF): "follow the model", "manipulate the same object", and "forage together". We found that older infants were the most attentive and most socially-influenced foragers among the three age categories in absolute terms, but were not more attentive than young infants given their low foraging activity. Juveniles, in contrast, tended to have reduced overall foraging intensity compared to infants, but showed relatively more MDF in cases in which they observed subadult or adult models. Female models appeared to be more attractive than male models. These findings suggest that infants are generally more attentive to the foraging behavior of subadults and adults than juveniles, with the latter being more influenced when they had observed a model before. These subtle age-dependent effects of social foraging not only extend the assumption that young primates seek information from adults, they also suggest a complex interplay among physical and cognitive maturation, independence, and social dynamics.     

On the ecology and behavior ofCebus albifrons in eastern Colombia: II. Behavior

A 503-contact-hr study of a 35 member group ofCebus albifrons was conducted in eastern Colombia in 1977 and 1978. The reactions of the group often centered on the largest adult male, which seemed dominant over all other members of the group. This “alpha” male reacted to perceived danger by putting himself between the group and the danger where he threatened and observed until the other members left the scene. Many members of the group sought the alpha's physical support while using threatening behaviors. Much tolerance towards juveniles and infants was shown by adult and subadult males which included carrying young animals out of danger. Territorial behavior was observed towards neighboring groups. Many behaviors were similar to other species ofCebus.     

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.     

Time budgets ofMacaca mulatta

We measured the amount of time that 20 rhesus monkeys,Macaca mulatta, (four adult males, 10 adult females, four juvenile males, and two juvenile females) contained in two enclosed social groups devoted to 16 activities. For 14 of these 16 behaviors we found significant differences between age-sex classes. For 14 behaviors, there were also differences between individual monkeys. Twelve of the 16 activities showed significant diurnal variations. We discuss the relation between the use of time and social position, the adaptive significance of diurnal variation, and compare our data with that available for free ranging rhesus.     

Spatial movements and social networks in juvenile male song sparrows

The time between fledging and breeding is a critical period in songbird ontogeny, but the behavior of young songbirds in the wild is relatively unstudied. The types of social relationships juveniles form with other individuals can provide insight into the process through which they learn complex behaviors crucial for survival, territory establishment, and mate attraction. We used radio telemetry to observe social associations of young male song sparrows (Melospiza melodia) from May to November. Juvenile song sparrows were frequently observed in social flocks and generally associated with more birds in the summer than in the autumn months. Most juvenile subjects formed stable social relationships with other birds and were seen with the same individual on up to 60% of the days observed. The strongest associations occurred with other juvenile males, and these individuals were often seen <1 m from the subject, even when the subject moved large distances between tracking observations. Associations also had long-term behavioral consequences as subjects were more likely to establish territories near their associates and learn shared song types. Our results indicate that male song sparrows spend a large percentage of the juvenile life stage forming social relationships and suggest that these associations may be important for the ecology of young birds and the ontogeny of their behaviors.     

Adoption of a Wild orphaned ringtailed lemur infant by natal group members: Adaptive explanations

In December 1992 an infant ringtailed lemur, approximately 7 weeks of age, was orphaned in one of the regularly-censused social groups at the Beza-Mahafaly Reserve, southwestern Madagascar. The infant was initially adopted by a subadult (2 yr-old) male from the group. Continuous-time focal animal data were collected for a 12-hr period, from the time that the infant was retrieved by the young male, in order to document the adoption process. Ten members of the infant's social group (total group number=18) engaged in infant care behaviors over the 12-hr period. The subadult male spent the most time engaged in infant care, and he and one adult female exhibited the highest frequency of caregiving behaviors over the 12-hr period (p<0.001). Four adult males also initially cared for the infant. The orphan was one of only six infants in the reserve population to survive that year. She was censused two years later as an adolescent member of her natal group. Adaptive explanations for this adoption vary depending upon the care-giver. For the subadult male and adult female caregivers, kin selection can be suggested, as the infant was related to all females and immature animals in the group. Adult males may have exhibited caregiving behaviors as a strategy related to affiliation with adult females which could lead to potential mating and reproductive success.     

Social scratch: Another custom in wild chimpanzees?

Chimpanzees (Pan troglodytes schweinfurthii) in the Mahale Mountains National Park, Tanzania, scratch other individual's bodies while they groom them. This behavioral pattern of “social scratch” is another example of locality-specific social behavior, or custom, as it is not found in the Gombe National Park, Tanzania, about 150 km north of Mahale, nor has it been reported from any other sites of chimpanzee study. Frequency of social scratch was correlated with frequency of social grooming, but not with frequency of self-scratch. Frequencies of social scratch per grooming bout among adult and adoles-cent males, and from lactating females to infants or juveniles, were high, and among males, higher-ranking males especially received more. These facts indicate some social function of the behavior. Social scratch was directed mostly to the dorsal side of the body. However, when lactating females social scratched to infants or juveniles, they scratched other body parts. Social scratch was not lateralized to left or right. We present four hypotheses on the functional origin and on the learning process of this cultural behavioral pattern.