A case of adoption in a wild group of black-fronted titi monkeys (Callicebus nigrifrons)

We observed a case of infant adoption in an unprovisioned group of wild black-fronted titi monkeys (Callicebus nigrifrons). During our long-term field study we noticed that an infant had moved from one of our study groups (“Desbotado”) to another (“Rio”). Observations of the adoptive group confirm that it was being cared for by the adult male, and initially the group’s adult female was nursing the infant alongside her biological infant. Interestingly, the native and adoptive groups have frequent inter-group interactions, but at no point have we observed the native group trying to retrieve its infant. As of April 2007 the infant has been living in its adoptive group for 19 months. These data document the first case of adoption in this genus; they suggest that infant recognition is poorly developed in this species and that under certain circumstances wild groups of C. nigrifrons can successfully rear twins. In our study population reproductive females give birth to one infant every year; the only case when this has not happened is with the group that adopted the infant, suggesting that adoption may generate a reproductive cost.     

Adoption in free-ranging red howler monkeys,Alouatta seniculus of Venezuela

This report describes three cases of infant adoption in red howler monkeys (Alouatta seniculus) of Venezuela. In one case, a lactating female adopted her infant granddaughter after the infant's mother disappeared and the infant survived for the next 25 months. In the second case, an adult female adopted her infant granddaughter for nine days while the infant's mother was still a group member. In the third case, a nulliparous female temporarily adopted an infant from a neighboring group. The details and the possible reasons for these adoption are described.     

Infant Carrying Behavior in Callitrichid Primates: Callithrix and Leontopithecus

Care of offspring by individuals other than the mother is ubiquitous in callitrichid primates. In spite of its widespread occurrence, however, there is considerable taxonomic variation in the timing and intensity of parental effort by breeding males and nonbreeding juvenile group members. These differences may be attributable to generic and specifies differences in the costs of reproduction for females or in ecological constraints on travel and foraging. We present data on patterns of infant carrying in social groups of two taxa of callitrichid primates (Callithrix and Leontopithecus) throughout the first 3 months of infant life. We evaluated patterns of care in small groups (two or fewer juvenile or subadult helpers) and in large groups (three or more helpers in addition to the breeding adult male and female). Group size had little effect on levels of maternal carrying effort in either marmosets or lion tamarins, and mothers ceased carrying infants by 3 months of age. Carrying efforts by fathers were significantly reduced in groups with many helpers relative to small groups. Helpers carried at consistent rates during the second and third months of infant life in Leontopithecus, while in Callithrix, carrying by helpers peaked during the second month. These results suggest that if helpers reduce energetic demands on lactating females, the mechanism by which helpers reduce these burdens is independent of maternal carrying effort.     

Social behaviour and infant carrying in a group of moustached tamarins,Saguinus mystax (primates: Platyrrhini: Callitrichidae), on Padre Isla,Peruvian Amazonia

The social behaviour of a group of eight moustached tamarins,Saguinus mystax, (five males, three females) was studied on Padre Isla in northeastern Peru. About 60% of all allogrooming was done by the two adult males in the group, and about 11% by a young adult female. All other group members groomed very little. The adult breeding female received more grooming than any other group member. After the death of the adult female (preyed upon by an anaconda) the amount of active allogrooming remained constant for all group members except for the young adult female, who increased her contribution to about 30%. Her preferred grooming partner was the subadult female, which generally screamed when being groomed by the young adult female and terminated grooming by going away. This kind of grooming relation is termed “forced grooming” and is interpreted as a possible social control mechanism. The young adult female groomed the adult males more often after the death of the adult female than before. This might have had the function of strengthening the social bond with the adult males and in obtaining the breeding position in the group. After the death of the adult female, the vulva of the young adult female grew to full adult size. Agonistic behaviour was less frequent than allogrooming. Most aggressive interactions (50%) originated from the subadult male of the group. The young adult female was the target of most of these aggressions. Extremely little aggression occurred between the three females. The young adult female was the only individual who tried to emigrate from the group during the study period. Her attempt to join a neighbour group failed due to rejection by all four members of this group. All group members participated in carrying an infant, but the adult males and the young adult female carried most frequently. Contribution to infant carrying varied with the infant's age.     

Functional responses of Iphiseius degenerans and Neoseiulus teke (Acari: Phytoseiidae) to changes in the density of the cassava green mite, Mononychellus tanajoa (Acari: Tetranychidae)

The functional responses of protonymph and adult female Iphiseius degenerans and Neoseiulus teke to increasing density of three stages of their prey, the cassava green mite (CGM), Mononychellus tanajoa, were studied on excised cassava leaf discs under laboratory conditions. The responses obtained were predominantly sigmoid type III curves with the highest plateau when both stages of I. degenerans and N. teke were preying on CGM eggs. In all cases, the predation rate of the former species exceeded that of the latter. The empirical data were fitted by four different models. From the models, the attack coefficient (a) and handling time (T _h) were estimated. For a given predator stage (protonymph or adult female), the predator's attack coefficient declines and handling time increases as the prey gets larger. For a given prey stage, the predator's attack coefficient increases and handling time decreases as the predator stage becomes larger.     

An attempted within-group infanticide in wild chimpanzees

Two high-ranking adult male chimpanzees (Pan troglodytes) of M group in the Mahale Mountains National Park, Tanzania, tried to get a newborn female infant of an adult female who was born in M group. The mother was not seen to mate with these adult males during the probable conception cycle of the infant, but she disappeared from the group during the later cycle, when she may have been inseminated by a male of one of the neighboring unit groups. The adult males failed to get the infant because the grandmother of the newborn and her female friend cooperated to protect the mother and infant from attacks by the males. The sexual selection hypothesis for infanticide by adult male chimpanzees holds for this observed case. The sudden disappearance of another infant, a healthy female, strongly suggests the killing of female infants too. Therefore, the asserted male-biased infanticide in chimpanzees appears to be less tenable.     

Attacks on neonates by a male mangabey (Cercocebus atys)

Aggressive behavior by an adult male toward selected infants and their mothers was observed during a long-term study of reproduction in a captive social group of sooty mangabeys (Cercocebus atys). The highest-ranking adult male in this group was observed to attack and bite three neonates out of a total of 13 infants born in 1982. All three attacks were directed attacks in which infants were grabbed from their mothers and bitten in the head. The first infant was fatally injured; the other two probably would have sustained fatal wounds had the male's canines not been blunted beforehand and had observers not intervened. The attacks were preceded by a pattern in which the male persistently stalked or chased the mother-infant pairs, a behavior first observed in the hours immediately following parturition. Unlike attacks in wild baboon groups following male immigration, these attacks on infants occurred in a stable social group in which the male attacker had been a lifelong resident. This male, however, had gained alpha rank only 3 months before attacking the first infant. These attacks, in the context of other evidence of aggression and wounding, are discussed relative to current models of infanticide in primates.     

Social integration of a bonobo mother and her dependent daughter into an unfamiliar group

In the present study, we obtained quantitative behavioral data on the integration process of an adult female with her dependent daughter into a resident zoo population of six bonobos (Pan paniscus). During the whole observation time of almost two months, the integration happened very peacefully without significant increases of aggressive or agonistic tendencies. The integration was mediated and actively supported mainly by two processes: contacts of resident infants and juveniles towards the immigrating animals and contacts of the immigrating adult female to a “specific senior female” of the resident group. Adult males and adolescent females seemed not to play a role in the social integration of new group members. The new adult female soon became a preferred partner for sexual interactions such as genito-genital rubbing. The social integration of the 18-month-old young was controlled by her mother and finished only after the adult female had reached a stable and safe position in the new group. According to our observations, the exchange of an adult female bonobo including her young between zoos has no negative effects on the animals involved.     

Adult male replacement and social change in two troops of hanuman langurs (Presbytis entellus) at Jodhpur,India

I studied the process of adult male replacement and social change in two one- male troops (B20 and B21) of hanuman langurs (Presbytis entellus)at Jodhpur, India. Male-male competition lasted for about 6 months before the successful takeover of one troop (B20). During that period, five adult males from three neighboring bands (AMB7, AMB9, and AMB10) and a resident male of a neighboring troop (B21) were involved in taking over the troop. The latter male also copulated with six females during his interim residency, which suggests that he may have opportunistically maximized his mating chances with females of a neighboring group. During an intertroop interaction, a 14-month-old female infant of the other troop (B21) was fatally attacked by an adult female of the first troop and the infant eventually died. The attacker may have taken advantage of the disorganization created by male-male competition, perhaps to eliminate a future food competitor. In addition, the first troop gained an additional feeding area from the other troop’s range; it included a sleeping site and a waterhole, indicating that territorial fights during social instability may have led to the expansion of the winner’s resource area.     

Fatal intragroup kidnapping in yellow baboons

The fatal kidnapping of a 5-day-old baboon (Papio cynocephalus) in Amboseli National Park, Kenya, is described. Although pulling and rough handling of primate infants by nonmothers are frequently observed, records of fatal intragroup kidnappings are rare. In the instance described here, the mother, a healthy, primiparous female, did not retrieve the infant from the kidnapper, a higher-ranking juvenile female of the same group, until he died 3 days later, presumably from starvation or dehydration. This incident is compared with other fatal intragroup kidnappings in nonhuman primates and related to adaptive interpretations.     

The effects of infant births on male–female relationships in Cebus capucinus

Most primates are characterized by cohesive male–female bonds that are maintained year round. While recent studies have addressed the selective pressures influencing the evolution of male–female relationships in primates, we know relatively little about the proximate mechanisms affecting them. It has been demonstrated that newborn white‐faced capuchins (Cebus capucinus) attract the attention of other group members and this may be an important mechanism influencing male–female relationships. We studied two groups of C. capucinus in the Area de Conservación Guanacaste, Costa Rica, between February and July 2007. A total of 348 hr of focal data were collected on all adult males (n=6) residing in each of the study groups. During our study, 13 of the 14 group females were either pregnant or lactating, and 9 infants were born. We calculated an average daily affiliation rate between all group males combined and each adult female four weeks before and four weeks after the birth of her infant. Repeated measures ANOVAs revealed no significant changes in affiliation following infant births (F=2.262, df=1, P<0.176). Results remained nonsignificant for rank (F=1.550, df=1, P<0.260) and group membership (F=0.729, df=1, P<0.429). Infant sex was the only variable with a significant effect on affiliation rates between males and females (F=10.020, df=1, P<0.019). Adult males increased their affiliation with all adult females that gave birth to male infants (n=4), while their rates decreased with all but one of the adult females with female infants (n=4). While preliminary, these results indicate that the adult males may cultivate relationships with other males at a young age. Am. J. Primatol. 71:380–383, 2009. © 2009 Wiley‐Liss, Inc.     

Infant Development and Parental Care in Free-Ranging <Emphasis Type="Italic">Aotus azarai azarai</Emphasis> in Argentina

Studies of infant development and parental behavior in free-ranging owl monkeys have been constrained by their nocturnal habits. Taking advantage of the cathemeral activity pattern of Aotus azarai azarai in the Argentinean Chaco, we describe the development of a cohort of free-ranging infants born in an owl monkey population in Formosa Province. We observed 7 infants, whose birth dates are known to the nearest week, to record details of their development and care between October 1999 and March 2000. We collected 92 h of behavioral data in 76 sessions. The infants were almost never off the parents during the first 4 wk of life, and we observed no infant being transported by a nonadult. The parent carrying the infant traveled most frequently in the middle of the group, sometimes first, but rarely last. The mean duration of 33 nursing episodes is 69 sec. After nursing, the infant was more likely to return to the nonnursing adult than to remain with the mother suggesting that in owl monkeys the infant may be primarily attached to the adult male in the group. Infants began to explore, to manipulate and to consume solid foods during the second month. Our observations are comparable to ones on captive breeding groups of Colombian owl monkeys (Aotus lemurinus) and Bolivian owl monkeys (A. azarai boliviensis) under controlled conditions of temperature, illumination and food availability.     

Infanticide in chimpanzees: Review of cases and a new within-group observation from the Kanyawara study group in Kibale National Park

A prolonged attack on a mother and 2-year-old infant that resulted in the death of the infant was observed in the Kanyawara study group in Kibale National Park. The mother was a border-area resident who was first observed associating with unit-group males six years previously. The attackers were an adult male and an adult female with a 6-week-old infant clinging ventrally to her. The attack was unusual in several respects: it is the first time a male and a female chimpanzee have been observed cooperating closely in an infanticidal attack; the adult female initially attempted to intervene in the victim's behalf, but later joined in the attack after receiving aggression from the male; and the episode was longer in duration than other reported cases. In the year following the incident, the mother did not increase her association with community males, but was seen with the male who killed her infant. The relevance of these observations to sexual selection-based explanations for infanticide in chimpanzees is discussed.     

Infant care in the spectral tarsier ( Tarsius spectrum ) Sulawesi, Indonesia

I present quantitative and qualitative data on infant caretaking behaviors collected during a preliminary field study of spectral tarsiers (Tarsius spectrum),in a northern Sulawesi rain forest. The primary goal of the study is to identify the basic pattern of infant care in this species. I studied tarsiers at Tangkoko-Dua Saudara Nature Reserve in Sulawesi, Indonesia, from May to July 1992. I observed two infants, from two groups for a total of 96 hr using focal follows. During individual focal follows, ranging from 20 min to 6 hr, I recorded behaviors at 5-min intervals. I also recorded distances of group members relative to the infant at 5-min intervals. I subsampled the data at 35-min intervals to control for statistical autocorrelation between data points. Infants were alone between 40 and 50% of the time. The two subadults were more frequently in proximity to the infant than the adult males, the nonmatemal adult female, or the mothers were. This pattern of the subadults maintaining proximity to the infant continued when the mothers were absent. These results suggest that subadults may be guarding or babysitting infants. It is also possible that subadults are not traveling as far from the sleeping site as adults do and are therefore more likely to be found in association with the infant.     

Frequency of aggressive behavior and a case of mortal attack in wildMacaca sylvanus in the Middle Atlas region (Morocco)

We observed a mortal attack against an adult female in a wild population ofMacaca sylvanus in the Middle Atlas Cedar forest ecosystem near the town of Azrou, Morocco. This species is generally believed to be the least aggressive in the whole GenusMacaca. We investigated the possible factors responsible for such an extreme case of increased aggression such as: 1) density of population, 2) availability of food rescues, 3) male competition for females. During a twelve month behavioral observation, we compared the hourly agesex class aggression frequency in the population where the mortal attack occurred with another macaque population living in different ecological conditions relative to density, food distribution and distance from human settlements. The pattern of age-sex seasonal distribution of aggression shows that, in the Middle Atlas, the adult female is the age-sex class most involved in aggressions and especially during food shortage and when resources are patchily distributed, as in the case were the mortal attack occurred.     

Predation on giant flying squirrels (Petaurista philippensis) by black crested gibbons (Nomascus concolor jingdongensis) at Mt. Wuliang, Yunnan, China

Predation on vertebrates is infrequent in gibbons. In a 14-month field study of the central Yunnan black crested gibbon (Nomascus concolor jingdongensis) at Mt. Wuliang, Yunnan, China, we observed gibbons attacking, killing and eating giant flying squirrels (Petaurista philippensis). During 845 h of observation on one study group, the gibbons attacked giant flying squirrels 11 times, and succeeded in 4 cases. Although all members of the group attempted to attack the squirrels, all four successful attacks were made by the same adult female. The victims were infants in three cases and a juvenile or sub-adult in one case. Black crested gibbons also attacked adult giant flying squirrels by grabbing their long tails and throwing them from the canopy, but they failed to catch or kill the prey in three cases observed. Passive meat sharing occurred in three out of four successful cases. Besides hunting giant flying squirrels, the black crested gibbons also ate eggs or chicks in two birds’ nests and one lizard.     

Evidence for sexually selected infanticide in captiveCercopithecus mitis,Cercocebus torquatus,andMandrillus leucophaeus

Adult resident males of one-male-multi-female primate groups housed at the Hannover Zoo exhibited aggression, when confronted with nonadult individuals, which were fathered by other males: (1) a new adult resident male in a group of blue monkeys killed a 5.8-month-old female infant: (2) a new adult resident male in a group of white collared mangabeys injured a 24.0-month-old female and an 18.9-month-old male severely; they would have died without veterinary care; and (3) the resident male of a group of drills threatened an 1.8-month-old foreign female infant seriously; efforts to introduce the infant were discontinued. Pathological explanations are unlikely because the adult males showed no aggression towards own nonadult offspring under the same captive conditions. By and large, the events support the theory that infanticide is the result of sexual selection among males.     

EQUIPMENT REVIEWS

ABSTRACT

Research on African elephant (Loxodonta africana) vocal communication has increased in recent years, yet there has been very little data collected on the vocal production of infant African elephants. Vocalizations were recorded from a group of five adult female African elephants and 3 dependent offspring (1 male and 2 female) at Disney's Animal Kingdom, Florida, U.S.A., using custom-designed audio-recording collars worn by the adult females. We measured both source and filter features of infant ‘rumble’ vocalizations made during affiliative social interactions and after cessation of nursing from adult females. Rumble vocalizations produced in the ‘nurse cessation’ context exhibited an upward shift in formant frequency locations, compared to rumbles produced during the ‘affiliation’ context. Additionally, call duration increased and fundamental frequencies decreased after nurse cessations for the male, but both females showed the opposite acoustic response. When infant rumbles accompanied nurse cessations, nursing was more likely to resume within 30 seconds compared to nurse cessations without vocalizations. These results suggest that infant rumbles associated with cessation of nursing reflect the motivational state of infants and may influence maternal responsiveness.     

Discrimination of mother by infant among Japanese Macaques (Macaca fuscata)

Experiments on five mother-infant pairs of Japanese monkeys (Macaca fuscata)living together in a captive group were conducted during the first 12 weeks after birth in order to assess the time at which infants begin to discriminate their own mothers from other adult females. After removal from their social group, infants exposed to their mothers and three unfamiliar adult females at a distance of 150 cm failed to orient visually toward their mothers. However, when the infants were allowed to approach the four females, they responded preferentially to their mothers during the third month of life. We concluded that by 8–12 weeks of age, infant Japanese macaques are able to discriminate between their mothers and other adult females.     

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.