Rook,But Not Jackdaw,Post‐Conflict Third‐Party Affiliation Reduces Aggression for Aggressors

Post‐conflict (PC) affiliation refers to positive social interactions that occur after fights. Although this behavior has been widely studied, its functions are rarely tested. We examine a potential function of PC third‐party affiliation (affiliation between former opponents and bystanders) in rooks and jackdaws by investigating the hypothesis that conflicts lead to further aggression and that PC third‐party affiliation increases to reduce such aggression. The results show that PC affiliation reduces PC aggression for rook aggressors who were less likely to receive aggression after conflicts when they were affiliating with another vs. when they were alone. The opposite result was found for victims of both species who received more aggression after conflicts, and this aggression was not reduced by the act of affiliating. Finally, for jackdaw aggressors, the amount of aggression received after conflicts was not influenced by whether the individual was affiliating or alone, indicating that PC third‐party affiliation may serve a function that we did not examine. These findings highlight the importance of investigating functional differences in PC affiliative behavior according to the role played in the conflict.     

Postconflict behavior in captive western lowland gorillas (Gorilla gorilla gorilla)

Postconflict (PC) behaviors, including reconciliation and consolation, have been observed in many primate and several nonprimate species. Using the PC-matched control (MC) method, PC behavior was examined in two groups (n=13) of captive western lowland gorillas, a species for which no conflict resolution data have been published. Analyses of 223 conflicts showed significantly more affiliation between former opponents after a conflict when compared to control periods, indicating reconciliation. Results also showed significantly more affiliation between the victim and a third-party after a conflict, indicating consolation. Both solicited and unsolicited consolation were observed. The majority of the affiliative interactions observed for both reconciliation and consolation were social proximity, which suggests that unlike most nonhuman primates, proximity, rather than physical contact, may be the main mechanism for resolving conflicts in western lowland gorillas. PC behavior was not uniform throughout the groups, but rather varied according to dyad type.     

Pregnancy diagnosis in the common marmoset (Callithrix jacchus jacchus).

Abdominal palpation of the uterus was carried out on 25 pregnant and 29 non-pregnant marmosets (Callithrix jacchus jacchus). 195 complete 24-hour urine specimens, collected between the first week of gestation and term (21 weeks), were tested with the Sub-Human Primate Tube (SHPT) test. No significant differences between the two methods in their ability to diagnose pregnancy were obtained between the first and 13th week of gestation. The SHPT test was seldom positive after the 13th week of pregnancy, whereas, with one exception, palpation always indicated pregnancy.     

Ingestion of calcium solutions by common marmosets (Callithrix jacchus)

Callithrix jacchus, the common marmoset, is a small New World primate that feeds on insects, fruit, and gum, and has a high reproductive rate for a primate. Insects are generally a poor source of dietary calcium, while gums may contain significant levels of calcium. Their high reproductive rate also suggests that reproductive female C. jacchus might be susceptible to calcium deficiency. Thus, we hypothesized that common marmosets might find solutions containing calcium to be palatable. We used choice experiments to examine this phenomenon in 14 male and 19 female common marmosets. Animals were presented with identical water bottles containing either deionized water or a calcium lactate solution (either 2% or 4% calcium lactate by weight) and intake was measured. Serum 25-OH-vitamin D was monitored in a subset of the animals in the experiment to examine the role of vitamin D in this behavior. Our results demonstrated that C. jacchus can distinguish between plain water and a calcium lactate solution, and that in general they prefer calcium solutions. Although animals with marginal vitamin D status did have strong preferences for calcium solutions, they did not ingest significantly more of the calcium solutions than animals that were vitamin D-replete. Nulliparous females and males did not differ in the amounts of calcium solutions ingested. Lactating females ingested the greatest volume of the calcium solutions.     

Neighbor effects in marmosets: social contagion of agonism and affiliation in captive Callithrix jacchus

Researchers have demonstrated the neighbor effect for affiliative and agonistic neighbor vocalizations in captive chimpanzees. We extend the investigation of the neighbor effect to New World monkeys, Callithrix jacchus. We collected data on vocalizations and behaviors of 31 focal individuals and concurrent neighbor vocalization within three behavioral categories: intragroup and intergroup aggression and intragroup affiliation. We investigated whether there was an influence of neighbor vocalizations on focal behavior within the same behavioral category. For data analysis we used approximate randomization of paired‐sample t‐tests. We found that marmosets performed intergroup aggressive behavior (bristle, anogenital present for neighbor loud shrill only) for significantly longer, and emitted significantly more intergroup agonistic vocalizations (twitter, loud shrill), at a high frequency of intergroup agonistic neighbor vocalizations (twitter, loud shrill) than at low. The marmosets were also significantly more likely to engage in bristle behavior immediately after hearing a neighbor intergroup aggressive call (twitter, loud shrill) than directly beforehand. High neighbor intragroup agonistic calls (chatter) were associated with significantly longer spent in related behavior (composite of: attack, chase, steal food). Affiliative behaviors (share food, grooming invite) were engaged in by marmosets for significantly longer at higher frequencies of affiliative neighbor chirp calls than at low. Marmosets were also significantly more likely to perform food sharing and active affiliative contact immediately after rather than before hearing a neighbor chirp call. Our findings suggest that neighbor vocalizations influence marmoset behavior through social contagion and indicate that the neighbor effect for affiliation and aggression generalizes to the marmoset. Am. J. Primatol. 72:549–558, 2010. © 2010 Wiley‐Liss, Inc.     

Bromocriptine administration lowers serum prolactin and disrupts parental responsiveness in common marmosets (Callithrix j. jacchus)

The influence of prolactin on parental responsiveness was investigated in eight unpaired, parentally inexperienced common marmosets (Callithrix jacchus; 6 female, 2 male). The marmosets were prescreened with infants (1-10 days of age) and required to exhibit short latency retrieval and infant carrying in at least three consecutive pretests as criterion for inclusion in this study. The marmosets were then administered the dopamine agonist bromocriptine (0.5 mg/0.5ml vehicle subcutaneously) and the vehicle alone (0.5 ml 10% ethanol solution) twice daily for 3 consecutive days in random order. Bromocriptine treatment reduced circulating prolactin to nondetectable levels. Bromocriptine treatment eliminated infant retrieval in four of the eight marmosets and was associated with significantly increased retrieval latencies and significantly reduced carrying durations in the four monkeys that continued to retrieve following bromocriptine treatment. When given the vehicle alone, the marmosets retrieved infants significantly faster than during pretests, suggesting a handling effect of the injection series. Bromocriptine treatments were associated with significantly increased movement during the tests. The results of this study indicate that prolactin and/or its regulatory neurotransmitters are involved in the control of the spontaneous display of parental responsiveness in common marmosets.     

Ontogeny of monooxygenase activities in the marmoset monkey (Callithrix jacchus).

The pre- and postnatal development of monooxygenases in the liver and adrenal gland of marmoset monkeys (Callithrix jacchus) was investigated. Cytochrome P450 was detected in the fetal adrenal gland, but aldrin epoxidase, ethoxycoumarin O-deethylase, and ethoxyresorufin O-deethylase activities were below detection limits. Although fetal hepatic cytochrome P450 was not detected, low activities of aldrin epoxidase and ethoxycoumarin O-deethylase, but no ethoxyresorufin O-deethylase, could be detected in fetal liver. These enzymes attained adult marmosets activities when the offspring were approximately 2 months of age.     

X-ray-induced translocations in marmoset (Callithrix jacchus) stem-cell spermatogonia

The induction of reciprocal translocations in spermatogonial stem cells of marmosets (Callithrix jacchus) was studied after irradiation with different doses of X-rays (50, 100 and 200 rad) via spermatocyte analysis many cell generations later. The obtained results show a dose-effect relationship with clear saturation effects at 200 rad. The recorded frequencies of translocations were much lower than those reported for closely related marmosets (Saguinus fuscicollis and Saguinus oepidus). Possible reasons for this difference are discussed.     

Canine Reconciliation and Third‐Party‐Initiated Postconflict Affiliation: Do Peacemaking Social Mechanisms in Dogs Rival Those of Higher Primates?

Conflicts over food, access to mates, or other limited resources can sometimes escalate into aggression. In species that form social groups, these aggressive conflicts can jeopardize the benefits of group living, such as enhanced access to valued resources, necessitating the development of behavioural mechanisms that either mitigate conflicts, prevent aggressive escalation or resolve disputes. Two important mechanisms for managing the effects of disputes involve postconflict (PC) affiliative behaviour, either between the former opponents (called ‘reconciliation’) or between one opponent and a third party. Even though numerous studies have tested reconciliatory and third‐party affiliation tendencies in primates, for non‐primate animals little systematic data are available. We performed behavioural observations on three groups of captive domestic dogs (Canis familiaris) and used a PC/MC method to test the existence of reconciliation and third‐party affiliation in this species. The results of this study clearly indicate that both reconciliation and third‐party PC interactions are present in the domestic dog, and form important social mechanisms of the domestic dog. Furthermore, familiar individuals showed a significantly higher proportion of reconciled conflicts than did unfamiliar individuals, and also displayed fewer conflicts. Finally, we show that most of the third‐party affiliations involve the victim of a conflict and that victim‐directed affiliation outweighs victim‐initiated third‐party affiliation in these PC interactions.     

Heinz bodies do not modify the membrane characteristics of common marmoset (Callithrix jacchus) erythrocytes

The possibility was examined that the membrane function of erythrocytes obtained from healthy common marmosets (Callithrix jacchus) was modified by the presence in the cells of Heinz bodies. No significant differences were found in erythrocyte endogenous free malonyl dialdehyde (MDA) or reduced glutathione (GSH) between normal human erythrocytes and marmoset erythrocytes containing Heinz bodies. Membrane fluorescent chromolipids, surface charge and thiol levels were similar in both species but average membrane bulk lipid fluidity was slightly elevated in the marmosets. It was concluded that, in contrast to the situation in human erythrocytes, the presence of Heinz bodies in red cells of marmosets does not adversely affect the properties of the membrane.     

Reconciliation following aggression in patas monkeys,Erythrocebus patas

Following intra-group aggression, obvious conciliatory displays are absent from the behavioural repertoire of patas monkeys, Erythrocebus patas, while many other Old World primate species show special reconciliation gestures. When 10-min focal-animal samples that began after spontaneous aggression were compared with matched-control samples, captive adult female patas followed up on aggressive interactions, interacting sooner and more often with former opponents during post-conflict observations than during matched-control observations. Almost one-third of post-conflict observations included affiliative behaviour between former opponents, which is termed reconciliation. Matrilineally related opponents were more likely to reconcile with one another than were unrelated animals. No effect of the dominance hierarchy on tendency to reconcile was found. Thus, patas monkeys showed general patterns in post-conflict behaviour that were similar to those seen in other primates previously investigated.     

Postconflict third-party affiliation in rooks, Corvus frugilegus

Conflict features in the lives of many animal species and induces social stress mediated by glucocorticoid hormones [1]. Postconflict affiliation, between former opponents (reconciliation) or between former opponents and a bystander (third-party affiliation), has been suggested as a behavioral mechanism for reducing such stress [2], but has been studied almost exclusively in primates [3]. As with many primates, several bird species live in social groups and form affiliative relationships [4]. Do these distantly related animals also use affiliative behavior to offset the costs of conflict? We studied postconflict affiliation in a captive group of rooks. Unlike polygamous primates, monogamous rooks did not reconcile with former opponents. However, we found clear evidence of third-party affiliation after conflicts. Both initiators and targets of aggression engaged in third-party affiliation with a social partner and employed a specific behavior, bill twining, during the postconflict period. Both former aggressors and uninvolved third parties initiated affiliative contacts. Despite the long history of evolutionary divergence, the pattern of third-party affiliation in rooks is strikingly similar to that observed in tolerant primate species. Furthermore, the absence of reconciliation in rooks makes sense in light of the species differences in social systems.     

Poxvirus infection in a colony of common marmosets (Callithrix jacchus)

An epizootic poxvirus infection occurred in a colony of 80 common marmosets (Callithrix jacchus) recently introduced to a laboratory facility. Over an 18-week period, 29 of the monkeys exhibited skin lesions that persisted for 4-6 weeks. Although eight marmosets died during the outbreak, their deaths were not attributed directly to the poxvirus infection. The skin lesions developed over the entire body surface including the soles and palms. Initially characterized as erythematous papules, they quickly changed to elevated coalescing lesions with extensive scab formation. Histopathologically, the lesions revealed moderate to marked acanthosis, and they progressed to full-thickness epidermal necrosis and ulceration. Intracytoplasmic inclusion bodies were observed occasionally within degenerate keratinocytes. These inclusions most probably constituted the intracytoplasmic aggregates of viral particles observed ultrastructurally and confirmed as members of the poxvirus group by negative staining of direct skin scrapings.     

Post-Conflict Affiliation in Two Captive Groups of Black-and-White Guereza Colobus guereza

Post‐conflict affiliation was studied in two captive groups of black‐and‐white guereza (Colobus guereza), a folivorous, arboreal species which lives in harems. The overall level of aggression was low and each individual was involved in only 0.054 aggressive interactions per hour. After 132 aggressive interactions observed during 364 h, former antagonists were found to seek each other out selectively and exchange affiliative behaviours. The first affiliative behaviour was likely to occur within the first minute after the end of the conflict. The post‐conflict affiliative behaviours most often seen were proximity, social grooming, embrace, reciprocal low‐intensity mouth‐opening, groom present and gentle hand touch, in descending order. The pattern of post‐conflict affiliation is thus similar to that observed in most other primate species studied. One notable exception seems to be the relatively high proportion of conflicts after which former opponents continue to remain within arm's reach (in 1/3 of the conflicts). If these instances of remaining‐in‐proximity were excluded, the corrected conciliatory tendency according to Veenema et al. (1994, Behav. Proc. 31, 29–38) was 45% (60% if they were included).     

Working memory of action: a comparative study of ability to selecting response based on previous action in New World monkeys (Saimiri sciureus and Callithrix jacchus)

Working memory of the outcome of one's own action is important for organizing and learning appropriate behaviors in a given condition. To examine whether non-human primates with different neocortical sizes show different abilities regarding working memory for action, the performance of squirrel monkeys (Saimiri sciureus) and common marmosets (Callithrix jacchus) in a kind of delayed-response task was compared. In this task, subjects were required to select a response based on short-term memory of the outcome of their own prior action, which requires working memory of action. These monkeys have a similar phylogenetic status (i.e. Ceboidea), but the size of the neocortex relative to the rest of the brain (relative size of the neocortex) is quite different. We found that both two species could attend to and remember their own actions and could select a response based on that memory. However, the performance level was higher for squirrel monkeys than for marmosets. These results suggest that non-human primates with differentially developed neocortices have different abilities regarding working memory of action.     

The puzzle-feeder as feeding enrichment for common marmosets (Callithrix jacchus): a pilot study

The use of a puzzle-feeder, as feeding enrichment, was investigated in three families of captive common marmosets (Callithrix jacchus). The study was carried out as a simultaneous choice test between two cages: one contained the puzzle-feeder, the other contained the usual food dishes, but otherwise both were arranged similarly. The monkeys were allowed to choose whether to feed from the usual dishes, or from the puzzle-feeder which required more effort. They were observed for two sessions in which they were differently motivated to feed. The enriched cage was always visited first, the marmosets managed to extract food from the puzzle-feeder, and spent more time eating from the puzzle-feeder when less hungry. These data contribute to a wider understanding on the use, and the effects, of feeding enrichments with different captive non-human primates.     

Reconciliation in wild white-faced capuchins (Cebus capucinus)

The likelihood of reconciliation (defined as preferential peaceful contact among former opponents following conflicts) has been predicted to vary positively with relationship value and compatibility, and negatively with relationship security. Long-term data on wild white-faced capuchins (Cebus capucinus) indicate that dyads consisting of an adult female and an alpha male have high value and compatibility, but low security. Two studies of C. capucinus postconflict (PC) behavior were carried out at Lomas Barbudal Biological Reserve, Costa Rica. One study consisted of 30-min PC and matched control (MC) follows. The second study extracted PC and MC periods from long follows, yielding PC/MC periods averaging 105 min. In study 2, but not study 1, significantly more PC/MC pairs were attracted (former opponents affiliated with each other sooner in the PC period than in the MC period) than were dispersed (former opponents affiliated with each other sooner in the MC period than in the PC period). Reconciliation in study 2 could not be explained as a by-product of former opponents' tendency to seek affiliative contact with conspecifics generally, or of the spatial proximity of opponents following conflicts. Attempted reconciliation was less likely to be followed by renewed aggression when reconciliation attempts were delayed following conflicts. The data were insufficient for a formal test of differences in conciliatory tendency (the difference between the number of attracted and dispersed PC/MC pairs, divided by the total number of pairs) among dyad types to be conducted.     

Individual olfactory signatures in common marmosets (Callithrix jacchus)

Individual discrimination is likely a prerequisite for most primate social interactions. Olfactory cues are one set of stimuli used by primates to discriminate between individuals. Despite the importance of these olfactory signatures, there is little published research assessing the existence or function of individually unique odors among primates. This review systematically assesses behavioral and biochemical aspects of individual odors in a New World primate, the common marmoset (Callithrix jacchus). There are three objectives to this review: First, behavioral evidence for odors unique to the individual is evaluated in the context of results demonstrating that marmosets are able to discriminate between the scents from a familiar and a novel individual conspecific in behavioral bioassays under a variety of conditions. Second, biochemical evidence for individual scent signatures is debated with reference to studies examining qualitative and quantitative differences between the chemical compositions of scent-mark pools from adult females. A combined gas chromatography (GC) and mass spectrometry (MS) analysis demonstrated that each female had a unique ratio of highly volatile chemicals in the scent mark that could affect individual discrimination. Finally, the possible adaptive significance of individual odors in marmosets is debated. Individual odors may play a key role in regulating both female intrasexual competition and intersexual communication by providing a basis for the assessment of individual quality.     

XY female marmoset (Callithrix jacchus)

A marmoset (Callithrix jacchus) with atypical external genitalia was phenotypically and genetically characterized. Testosterone concentration correlated with that of female marmosets. Externally, there was only one opening for the urethra. Internal genitalia were characteristic of those of female marmosets, and consisted of ovaries, with follicles in various developmental stages, and uterus. Microscopically, a normal vaginal structure was found. An XX/XY chimerism and high steroid hormone values are normally found in common marmosets. Genetic analysis was used for in vivo determination of sex. The Y-linked zinc finger protein gene (ZFY) last intron, and sex-determining region Y gene (SRY) exon were found by use of polymerase chain reaction and posterior sequencing analyses, indicating that this marmoset had Y-linked chromosome sequences. Normal SRY exons can, therefore, be associated with female internal sexual organs in marmosets; this may be the first XY female described in non-human primates.     

Exploratory behavior and learning in laboratory marmosets (Callithrix jacchus jacchus): Comparisons between experimental-cage and home-cage activity

In this paper I examine exploratory behavior and learning in two groups of common marmosets (Callithrix jacchus jacchus), both living under laboratory conditions. The main aim of my studies was to compare behavior occurring in an experimental testing situation with home-cage behavior, and to assess conditions under which exploration is enhanced. One group of marmosets was tested individually in an experimental room away from a larger animal holding room, and a second group was observed in their own home cages, surrounded by other marmosets. Marmosets in both groups were given the opportunity to learn simple tasks, such as pressing a lever for food or jumping on to a wire grid to open a door and see a neighbouring marmoset, and were provided with sets of novel or familiar objects to encourage play and exploration. In the isolated experimental cage, marmosets which learnt a lever-pressing task showed higher general activity levels than controls; in the home cages the mere addition of novel objects resulted in enhancements in exploratory behavior (measured in terms of contacts with the objects). Although the activities associated with learning tended to decline over time, the novel objects remained a constant interest throughout the experiment. The results have implications for maintaining marmosets in captivity, especially in situations when they are housed separately.