The caregiving/care-seeking balance in captive common marmosets (Callithrix jacchus)

A hypothesis to explain differences in infant social development in species with multiple caregivers is described. The hypothesis states that the distribution of an infant's time and activities amongst the individuals in its group is determined by the balance between the relative amounts of care-seeking by the infant and caregiving by the other members of the group. This generates several predictions that are investigated by experimentally reducing the care available to a group of infant common marmosets (Callithrix jacchus), and comparing their interactions with caregivers with those of a control group of infants that experienced normal levels of care. The results bear out several of the predictions. Infants receiving less care than usual spend less time in non-care-seeking activities and there are some increases in care-seeking behaviour. Infants continue to seek care differentially from different caregivers, and no compensation among caregivers in their behaviour towards infants is found.     

Scrounging facilitates social learning in common marmosets, Callithrix jacchus

The minimalistic environment of standard laboratory cages can adversely influence the responses of animals in standard behavioural tests and other aspects of the animals' biology. To avoid this, cages should provide for the animals' species-specific behavioural characteristics. We hypothesized that, given their possible capacity for colour vision, laboratory mice, Mus musculus, would show preferences between cages of different colours. Studies show that environmental colour can influence emotionality and task performance in humans, suggesting that cage colour could also affect emotionality and performance of mice in behavioural tests. Seventy-two mice were housed in home cages painted red, black, green or white. Five weeks later, 24 mice were placed individually into an apparatus allowing them to choose between cages of each of the home cage colours. Each mouse showed a highly significant preference, which overall, was unrelated to home cage colour. White cages were most preferred and red were least. Home cage colour had a significant effect on body weight and food consumption as well as on behaviour in a raised plus maze. Mice from red home cages spent most time in the closed arms, indicating greater anxiety, possibly suggesting that the reduced occupancy of the red preference cages resulted from avoidance of environmental conditions that induced a negative mental state. These findings show that laboratory mice have strong preferences between cages of different colours. We also found that an apparently inconsequential environmental variable, home cage colour, can influence responses in standard behavioural tests, which should be considered in assessing the external validity of such tests. Copyright 2003 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.     

Differential endocrine responses to infant odors in common marmoset (Callithrix jacchus) fathers

Olfactory cues can exert priming effects on many mammalian species. Paternally experienced marmosets, Callithrix jacchus, exposed to direct isolated olfactory contact with their own infant's scent show rapid decreases in testosterone levels within 20 min, whereas paternally inexperienced males do not. The following study tests whether there is a differential steroid response to exposure of infant scent from dependent infants (own and novel) and independent infants (own and novel). We examined the serum levels of estradiol, estrone, testosterone, dihydrotestosterone (DHT), and combined estrogens and androgens in eight male marmosets 20 min after exposure to isolated infant scent. Testosterone and androgen levels combined were significantly lower with exposure to own infant scent than a novel infant scent when the infants were at a dependent age but not at an independent age. Estrogen levels elevated significantly in response to own infant scent when the infants were at a dependent age but not at an independent age. These results suggest that marmoset fathers are more responsive to priming cues from related infants and hormonal responses from fathers are greatest when the infant is at a dependent age.     

Playful interactions in family groups of the common marmoset (Callithrix jacchus jacchus)

Play behaviour in six family groups of common marmosets (Callithrix jacchus jacchus) is described. Playful behaviour patterns comprised a distinct repertoire of behaviour and the patterns formed ordered sequences. The differences in the play of adults and offspring are described and analysed. Adult play was infrequent and most took the form of adult-offspring interactions; it contained fewer bouts of chasing and was less active, and adults elicited fewer bouts. No differences attributable to sex could be determined in the play of offspring and the only pattern that decreased with age was bouncing gait. Possible partner preferences were analysed, and it was found that marmoset twins showed an overall preference for playing with the twin. The vocalizations heard during bouts of play were recorded and analysed and their relationship to non-playful vocalization discussed; during bouts of play younger animals were found to vocalize to older animals. Marmoset play wrestling differed in form from aggressive wrestling, and patterns occurred during aggressive interactions which were not observed in play. The play of marmosets is discussed with regard to the socioecology of the species and compared to the play of other mammalian species.     

Bimodal temporal organization of specific vigilance behaviors in captive black tufted-ear marmosets (Callithrix penicillata)

The aerial/terrestrial scan and glance behaviors of 20 captive adult black tufted-ear marmosets (Callithrix penicillata), kept undisturbed in their own familiar social environments, were assessed at 07:00, 09:00, 11:00, 13:00 and 15:00 h, as little is known on the temporal organization of their vigilance repertoire, particularly under normal social and stress-free conditions. For each time point, four 20-min observation sessions were held. Although general high vigilance rates were observed, significantly more time was spent scanning the upper part of the home-cage, particularly during the earliest and latest hours of the day. Significantly higher terrestrial than aerial glance frequencies were also seen, yet both remained constant throughout the day. Therefore, the observed pattern not only varied significantly according to the specific vigilance behavior and time of day, but also seemed associated with eco-physiological factors, such as the search/intake of food, sleep site selection and higher risk of air-born threats.     

Interactions between parents and infants,and the development of independence in the common marmoset (Callithrix jacchus)

Detailed observations were made of the parent-infant interactions of five adult pairs and 31 infant common marmosets (Callithrix jachus), housed in captive family groups. Records of parental measures were taken up to 4 months old and comparisons made between infants in similar social situations. These comparisons investigate sex differences, birth-order variations, those between singleton and twin infants, parental variation and the proportion of time that older siblings carry infants. Correlations between the measures reveal that both parents are responsible for promoting and regulating increasing infant independence. In the discussion, comparisons are made with other parent-infant studies and problems of the adaptiveness of the Callitrichid social system considered.     

Reproduction in captive common marmosets (Callithrix jacchus)

Though sexual maturation may begin at around one year of age, first successful reproduction of the common marmoset (Callithrix jacchus) is likely to be later, and it is generally recommended that animals not be mated before 1.5 years of age. The average gestation period is estimated to be 143 to 144 days. A crown-rump length measurement taken by use of ultrasonography during the linear, rapid, prenatal growth phase (between approx. days 60 and 95) can be compared against standard growth curves to estimate delivery date to within 3 to 4 days, on average. Marmosets produce more young per delivery than does any other anthropoid primate, and have more variation in litter size. Many long-established colonies report that triplets are the most common litter size, and there is documented association between higher maternal body weight and higher ovulation numbers. Higher litter sizes generally do not generate higher numbers of viable young. Marmosets are unusual among primates in having a postpartum ovulation that typically results in conception and successful delivery; reported median inter-birth intervals range from 154 to 162 days. However, pregnancy losses are quite common; one study of a large breeding colony indicated 50 percent loss between conception and term delivery. The average life span for breeding females is around six years; the range of reported average lifetime number of litters for a breeding pair is 3.45 to 4.0. Our purpose is to provide an overview of reproduction in the common marmoset, including basic reproductive life history, lactation and weaning, social housing requirements, and common problems encountered in the captive breeding of this species. A brief comparison between marmoset and tamarin reproduction also will be provided.     

Birth and perinatal behaviour in family groups of the common marmoset (Callithrix jacchus jacchus), compared to other primates

Birth and perinatal behaviour in five family groups of the common marmoset are described. Information is given on 16 births, seven of which are described in detail.The birth process was divided into five stages; data are presented on the durations of the stages and the behaviours exhibited by the female in each stage.Infant marmosets cling unaided to the pelage of the female from birth, and the behaviour of neonates and the reactions of the female to infants are discussed.The interactions of other group members to the mother and neonates were analysed. The adult male's first interactions with the neonates appeared to occur much earlier (less than one hour after birth) than in other non-human primate species.Perinatal behaviour in marmosets is compared to that recorded in other non-human primate species and discussed in relation to the social organisation of C. j. jacchus.     

The development of infant-caregiver relationships in captive common marmosets (Callithrix jacchus)

The growing independence of infant common marmosets from their caregivers is promoted primarily by their caregivers, who increasingly often prevent the infants from climbing onto them and decreasingly often pick the infants up. Infants achieve independence from their mothers, fathers, and older siblings at different rates and develop characteristically different relationships with them. Infants that are most rejected by caregivers spend the least time on them. When rejected by their parents, infants tend to spend their time with their twins, rather than seeking to climb onto other caregivers. Caregivers do not compensate for unduly large or small amounts of care given by other members of the group. It is argued that if we are to understand the development of caregiver-infant relationships in species with multiple caregivers, we must discover the rules by which infants assess the amount of care they perceive themselves to have received and caregivers assess the amount of care they perceive themselves to have offered. The implications of a simple model based on expected levels of caregiving and careseeking are explored, particularly with respect to competition and compensation.     

Differential infant carrying in captive and wild common marmosets (Callithrix jacchus)

Callitrichids are communal breeders that lack sexual dimorphism, and only a few studies have examined behavioral gender differences among them. The purpose of this study was to investigate gender differences in infant carrying in 16 captive and seven wild common marmoset groups. Our results showed that female–female twin pairs were carried significantly more often by fathers than were male–male and male–female pairs both in the wild and in captivity. We suggest these differences may be related to different reproductive potentials of male and female Callithrix jacchus and possibly to future breeding competition among females.     

Individual recognition during bouts of antiphonal calling in common marmosets

Many vocalizations are encoded with a diversity of acoustic information about the signal producer. Amongst this information content are social categories related to the identity of the caller that are important for determining if and how a signal receiver may interact with that individual. Here, we employed a novel playback method in common marmosets (Callithrix jacchus) to test individual recognition during bouts of antiphonal calling. These experiments utilized custom, interactive playback software that effectively engaged subjects in antiphonal calling using vocalizations produced by a single individual and presented 'probe' vocalization stimuli representing a different individual at specific points within bouts of calling. The aim here was to test whether marmosets would recognize that the probe stimulus was a phee call produced by a different individual. Data indicated that marmosets were able to detect the change in caller identity; subjects produced significantly fewer antiphonal call responses to probe than control stimuli and, in some conditions, exhibited a shorter latency to produce the vocal response. These data suggest that marmosets recognize the identity of the individual during bouts of antiphonal calling. Furthermore, these results provide a methodological foundation for implementing the probe playback procedure to examine a broader range of social categorization during vocal interactions.     

Effects of positive interaction with caretakers on the behaviour of socially housed common marmosets (Callithrix jacchus)

Every aspect of the life of the captive non-human primates should be carefully attended to, as updated refinement concept recommends. Interaction with humans as environmental enrichment for these animals is believed to be of value, but it has been subject to little quantitative evaluation. This study investigates the effects of positive interaction with humans on the behaviour of a captive colony of common marmosets (Callithrix jacchus). The study was composed of two phases: baseline condition, where the interaction with humans was represented by routine care and management; and a second phase (‘Human Interaction Effects’), in which a familiar caretaker spent additional 20 min per day with each family, interacting actively and positively with the monkeys. In order to assess potential durable effects of such interaction, data were collected only when caretaker was absent. Between the two phases, a period of interaction 4 weeks long per family took place with the caretaker. The sampling method used was a 10 s scan sampling, with daily sessions 30 min long. Following the period of additional interaction with caretaker, the marmosets showed an increased level of grooming and playful activities, generally considered signs of increased level of welfare; however, they also showed lower levels of self-scratching and locomotion. A trend towards reduced contact vocalizations was also observed. These results suggest that simple, unstructured positive interactions between humans and marmoset monkeys may be part of a program aimed at maximising the level of welfare of captive non-human primates.     

Sex differences in food acquisition and aggression in captive common marmosets (Callithrix jacchus)

Competition for food within the social group has been postulated as an important factor affecting primate social organization. This study examined how factors such as sex, aggression, dispersion of food, and amount of difficulty involved in obtaining food affect the distribution of food in common marmoset (Callithrix jacchus) social groups. Mated pairs of adultC. jacchus were presented with food that was either dispersed or concentrated, and either difficult or easy, to obtain. The number of food pieces obtained, aggressive displays, incidents of physical aggression, and amount of time spent searching for food were recorded for each animal. Neither dispersion nor difficulty in obtaining food had significant effects on the distribution of food or any of the other behaviors examined. The primary factors affecting food distribution were aggression and amount of time spent searching. Females obtained more food than males in all situations because they were more aggressive and apparently more motivated to search for food than were males.     

Prolactin's mediative role in male parenting in parentally experienced marmosets (Callithrix jacchus)

Prolactin has been implicated in promoting paternal care behaviors but little evidence of causality has been found to date except for birds and fish. This study was designed to examine the possible causal relationships between prolactin and male parenting behaviors, reproductive hormones, and physical changes in cooperatively breeding common marmosets, Callithrix jacchus. Fifteen parentally experienced fathers were studied over three consecutive infant care periods during two weeks prior and three weeks following their mates' parturition under three-treatment conditions: normal control pregnancy, decreased prolactin and elevated prolactin. The treatments significantly altered the serum prolactin levels in the fathers. Using three methods of determining a father's level of parental care: infant carrying, family effort and responsiveness to infant stimulus tests, we found that only the male response to infant stimuli was altered by the hormone treatments. Lowering prolactin significantly reduced male responsiveness to infant stimuli but elevating prolactin showed the same effect. Hormonal sampling indicated that testosterone levels showed an inverse relationship to prolactin levels during a normal peripartum period and prolactin treatment reduced this relationship. Prepartum estradiol levels were significantly elevated during the lowered prolactin treatment and estradiol was significantly lowered postpartum with the elevated prolactin treatment. Father's weight decreased significantly by the third week of infant care during the normal treatment. Males in the elevated prolactin treatment lost little or no weight from prepartum while in the lowered prolactin treatment showed the most weight loss. The present findings did not distinguish a direct causal relationship of prolactin on behavior in experienced fathers but did find an interaction with other hormones and weight gain.