Female Long-tailed Macaques Research Articles

Long-tailed macaques: an unfairness model for humans

ABSTRACT The current study was designed to predict why human primates often behave unfairly (equity aversion) by not exhibiting equity preference (the ability to equally distribute outcomes 1:1 among participants). Parallel to humans, besides inequity aversion, lab monkeys such as kin of long-tailed macaques (Macaca fascicularis) also demonstrate equity aversion depending on their preference for the outcome (food) type. During the pre-experiment phase, a food-preference test was conducted to determine the most preferred income per individual monkey. Red grapes were the most preferred outcome (100%) when compared to vanilla wafers (0%). The first set of experiments used a 1:1 ratio (equity condition) of grape distribution among six kin-pairs of female long-tailed macaques, and we compared their aversion (Av) versus acceptance (Ac). In the second experiment, we assessed the response to the 0:2 and 1:3 ratio distribution of grapes (inequity condition). A total of 60 trials were conducted for each condition with N = 6 pairs. Our results show aversion to the inequity conditions (1:3 ratios) in long-tailed macaques was not significantly different from aversion to the equity conditions (1:1 ratios). We suggest that the aversion observed in this species was associated with the degree of preference for the outcome (food type) offered rather than the distribution ratio. The subjective preferences for outcome types could bring this species into irrationality; they failed to share foods with an equal ratio of 1:1.

The Dot-Probe Attention Bias Task as a Method to Assess Psychological Well-Being after Anesthesia: A Study with Adult Female Long-Tailed Macaques (Macaca fascicularis)

Understanding the impact routine research and laboratory procedures have on animals is crucial to improving their well-being and to the success and reproducibility of the research they are involved in. Cognitive measures of welfare offer insight into animals’ internal psychological state, but require validation. Attention bias – the tendency to attend to one type of information over another – is a cognitive phenomenon documented in humans and animals that is known to be modulated by affective state (i.e., emotions). Hence, changes in attention bias may offer researchers a deeper perspective of their animals’ psychological well-being. The dot-probe task is an established method for quantifying attention bias in humans (by measuring reaction time to a dot-probe replacing pairs of stimuli), but has yet to be validated in animals. We developed a dot-probe task for long-tailed macaques (Macaca fascicularis) to determine if the task can detect changes in attention bias following anesthesia, a context known to modulate attention and trigger physiological arousal in macaques. Our task included the following features: stimulus pairs of threatening and neutral facial expressions of conspecifics and their scrambled counterparts, two stimuli durations (100 and 1,000 ms), and counterbalancing of the dot-probe’s position on the touchscreen (left and right) and location relative to the threatening stimulus. We tested 8 group-housed adult females on different days relative to being anesthetized (baseline and 1-, 3-, 7-, and 14-days after). At baseline, monkeys were vigilant to threatening content when stimulus pairs were presented for 100 ms, but not 1,000 ms. On the day immediately following anesthesia, we found evidence that attention bias changed to an avoidance of threatening content. Attention bias returned to threat vigilance by the third day postanesthesia and remained so up to the last day of testing (14-days after anesthesia). We also found that attention bias was independent of the type of stimuli pair (i.e., whole face vs. scrambled counterparts), suggesting that the scrambled stimuli retained aspects of the original stimuli. Nevertheless, whole faces were more salient to the monkeys as responses to these trials were generally slower than to scrambled stimulus pairs. Overall, our study suggests it is feasible to detect changes in attention bias following anesthesia using the dot-probe task in nonhuman primates. Our results also reveal important aspects of stimulus preparation and experimental design.

Retrospective Evaluation of a Minor Dietary Change in Non-Diabetic Group-Housed Long-Tailed Macaques (Macaca fascicularis).

Simple SummaryMacaques in captivity are prone to becoming overweight and obese, which may cause several health and welfare problems. Diet likely plays an important role herein. In an attempt to reduce overweight incidence and related health problems, a minor dietary change was implemented in our long-tailed macaque breeding colony. The provisioning of bread was replaced by grains and vegetables, while the basic diet of monkey chow remained the same. Overweight status did not differ after dietary change, but some biochemical parameters related to glycemic response and lipid metabolism improved. This study emphasizes the importance of evaluating husbandry changes and shows that relatively minor dietary adjustments may improve animal health and welfare.Macaques in captivity are prone to becoming overweight and obese, which may cause several health problems. A diet that mimics the natural diet of macaques may prevent these problems and improve animal welfare. Adjusting captive diets towards a more natural composition may include increasing fiber content and lowering the glycemic index, i.e., reducing the impact on blood glucose levels. Such a dietary change was implemented in our long-tailed macaque (Macaca fascicularis) breeding colony. The basic diet of monkey chow pellets remained the same, while the supplementary provisioning of bread was replaced by grains and vegetables. This study is a retrospective evaluation, based on electronic health records, that investigated whether this minor dietary change had a beneficial effect on relative adiposity and overweight-related health parameters in 44 non-diabetic, group-housed, female long-tailed macaques. Relative adiposity was measured with a weight-for-height index and blood samples were collected during yearly health checks. Glycemic response and lipid metabolism were evaluated using several biochemical parameters. Relative adiposity and overweight status did not differ after dietary change. Yet, relatively heavy individuals generally lost body weight, while relatively lean individuals gained body weight, leading to a more balanced body weight dynamic. Dietary change did not affect HbA1c and triglyceride levels, while fructosamine and cholesterol levels were significantly reduced. Thus, the minor dietary change had no significant effect on overweight status, but some biochemical parameters related to the risk of diabetes and cardiovascular disease were positively affected. This study emphasizes the importance of evaluating husbandry changes and that critically reviewing husbandry practices can provide valuable insights to improve animal health and welfare.

Tubectomy of Pregnant and Non-pregnant Female Balinese Macaques (Macaca Fascicularis) With Post-operative Monitoring.

Worldwide, primates, and humans increasingly share habitats and often enter in conflict when primates thrive in human-dominated environments, calling for special management measures. Reproductive control is increasingly used to manage population growth but very few monitoring data are available. Therefore, the efficiency and implications of such programs require a careful examination. In the context of a contraception program in wild female long-tailed macaques in Ubud, Bali, conducted over four successive campaigns between 2017 and 2019, including 140 females (i.e., 41.9% of the reproductive females of the population in 2019), modifications of an endoscopic tubectomy procedure, a permanent sterilization method, clinical evaluation of this method, and the post-operative monitoring results of the neutered females after release are described. This surgical approach was applicable for pregnant females: 28.6% of the treated females were pregnant at the time of the surgery. The procedure used a single lateral port to reach and cauterize both oviducts in non-pregnant as well as in early to mid-term pregnant females. Pregnant females nearer to term required a second lateral port to access both oviducts masked by the size of the gravid uterus. Moreover, bipolar thermocauterization was utilized successfully without resection to realize the tubectomy. The average duration of the laparoscopic surgery was 14 min for non-pregnant females and 22 min for pregnant females. Animals were released 3 h 22 min in average following their capture. This short holding time, recommended for free-ranging primates, was made possible by the minimal invasiveness of the sterilization approach. A laparoscopic post-operative evaluation conducted on two patients during the following campaign confirmed that the oviducts were definitely disrupted and no longer patent. Moreover, no new pregnancies in sterilized females were recorded during the 3-year observation period. The survival rate of the treated females 6 months after sterilization was high (96.3%) with no major post-operative complications clinically recorded. Among females that were pregnant during surgery, 81.1% were confirmed to experience term delivery. This study demonstrates the safety and efficiency of endoscopic tubectomy, even for pregnant females, as a mean of wild macaques' population control.

Model psikologi komparatif ketidaksetaraan jumlah pembagian sumber daya: Studi pada Macaca fascicularis


 This study aims to promote Macaca fascicularis as a comparative psychology model in finding the root and solution of resource inequity by exploring inhibitor effect on refusal behavior, acceptance, and aggression toward the feed distribution numbers in six pairs of female long-tailed macaques. We observed the frequency of refusal behavior, acceptance, and aggression toward the distribution of red grape with a ratio of: a) 1:1, 0:2, 1:3 without environmental inhibitors (with an opened-aclyric tray) and b) ratios 1:1 with an environmental inhibitor (with a transparent restriction box) in 60 trials per condition. The sample size was N = 10. Non-parametric statistical analysis of Wilcoxon Signed-Rank Test showed that 1:1 ratio with environmental inhibitor produces a lower response of refusal behavior compared to 1:3 without inhibitor. It produced a lower response of aggression compared to other ratios. It produced a greater acceptance compared to other ratios. These long-tailed macaques do not accept the equity conditions except with environmental inhibitors. Based on this fact, we conclude that long-tailed macaques are a good spontaneous model for the comparative psychology of inequity.

Ultrasonographic features of liver, gallbladder, spleen, kidneys, and urinary bladder of rescued long-tailed macaques, Macacafascicularis

This study was conducted to determine the ultrasonographic features of the liver, gallbladder, spleen, kidneys, and urinary bladder of 24 apparently healthy male and female long-tailed macaques (LTM) and the correlations of organ measurements with body weight and crown–rump length. The animals were grouped into 12 males and 12 females. Examination was performed in sedated LTM using an ultrasound machine with 6.0 MHz microconvex scanner. Ultrasound appearance, dimensions, and echotexture of the liver, gallbladder, kidneys, spleen, and urinary bladder were evaluated. The results showed that there were no sex-related differences in echo mean values, thickness, and length of the selected abdominal organs. The liver was hypoechoic to isoechoic with the right renal cortex, while spleen was isoechoic to hyperechoic to left renal cortex. Spleen was hypoechoic to isoechoic to the liver. Gallbladder and urinary bladder had hypoechoic to hyperechoic thin wall with anechoic lumen. There was a statistically significant and moderate positive correlation between the volume of the left kidney and body weight. The right kidney volume was greater than the left kidney and the total renal volume had a statistically significant and moderate positive correlation with body weight. This study established the reference values for ultrasonographic features of selected abdominal organs of rescued LTM.

Both aggressive and affiliative behaviour facilitate resource access in high-ranking female long-tailed macaques (Macaca fascicularis)

Abstract Access to limited resources may be achieved by dominance as well as by high rates of aggressive and affiliative behaviour. We investigated the relative effectiveness of dominance rank and aggressive and affiliative behaviour in accessing three material and three social resources. Aggressive and affiliative behaviour of 24 female long-tailed macaques was scored along with their success in resource access. Path models revealed that high-ranking individuals have more access to resources than low-ranking ones through their employment of both aggressive and affiliative behaviour. Physical aggression was effective in accessing two material resources (food and enrichment). Affiliative behaviour was effective in accessing one material (co-drinking) and one social (tolerance) resource. In conclusion, since aggressive behaviour was effective in accessing two material resources, while affiliative behaviour increased access to both a material and a social resource, affiliative behaviour is at least as important as aggressive behaviour for high-ranking individuals to access resources.

Relationship between menarche and fertility in long-tailed macaques (Macaca fascicularis).

We attempted to elucidate female reproduction in long-tailed macaques (Macaca fascicularis). These monkeys have a non-seasonal menstruation cycle, which makes them suitable subjects for studies in a variety fields including medical science and regenerative medicine. We analyzed individual breeding data including time of menarche, start of regular menstruation, and first pregnancy. These three events are related to the maturation of female long-tailed macaques. All research subjects were female long-tailed macaques bred at the Tsukuba Primate Research Center. The study comprised 45 females; we included time of menstruation, male-female cohabitation, and first pregnancy in their growth records. We extracted age and weight data relating to menarche, start of regular menstruation, and first pregnancy from these records. In the two years typically required from menarche to first pregnancy, the body weight increased by approximately 500 g (21% of the weight at menarche); it is clear that there is a significant physical change after menarche. Our findings suggest that female monkeys are not necessarily mature enough for pregnancy at menarche. Therefore, the use of the word “maturity” in terms of fecundity may be more accurate after the start of regular menstruation. This is what we term “adolescence” in the developmental process. Therefore, M. fascicularis monkeys are candidates for an animal model of human adolescence.

Social behavioral changes in MPTP-treated monkey model of Parkinson's disease.

Parkinsonian patients experience not only the physical discomfort of motor disorders but also the considerable psychological distress caused by cognitive deficits and behavioral disorders. These two factors can result in a disruption of social relationships during the symptomatic and even the presymptomatic motor states of the disease. However, it remains difficult, if not impossible, to evaluate social relationships in presymptomatic patients. The present study focused on the evaluation of social relationships within a group of female long-tailed macaques during presymptomatic and symptomatic motor states induced by Chronic Low-Dose (CLD) and then Chronic High-Dose (CHD) systemic administration of 1-methyl-4-phenyl-l,2,3,6-tetrahydropyridine (MPTP). Dopaminergic denervation within basal ganglia and cortical areas was evaluated using Positron Emission Tomography (PET) scans with 18F-DOPA (6-[18F]-fluoro-L-3,4-dihydroxyphenylalanine) radiotracer. Interestingly, social behavioral changes could be identified in the presymptomatic motor state before any motor and/or cognitive impairment occurred. Stronger effects were observed in subordinate animals compared to dominant animals. From baseline state to CLD-presymptomatic motor state, the frequency of emitted affiliative and aggressive behaviors increased. From CLD-presymptomatic to CHD-presymptomatic motor states, the frequency of the three categories of social behaviors (aggressive, submissive and affiliative) decreased. At this time, quantitative data analysis in PET scans highlighted a dopaminergic denervation in the insula and the posterior caudate nucleus. Finally, the frequency of the three categories of social behaviors decreased during the stable-symptomatic motor state compared to baseline and presymptomatic motor states; this was also associated with motor and cognitive disorders and a dopaminergic denervation in all the evaluated cortical and subcortical structures.

Pair Housing for Female Longtailed and Rhesus Macaques in the Laboratory: Behavior in Protected Contact Versus Full Contact

Pair housing for caged macaques in the laboratory generally allows unrestricted tactile contact but, less commonly, may involve limited contact via grooming-contact bars or perforated panels. The purpose of using this protected contact housing, which prevents entry into pair-mates' cages, typically is to accommodate research and management requirements. The study used behavioral data collected on 12 pairs of female longtailed macaques (Macaca fascicularis) at the Washington National Primate Research Center and 7 pairs of female rhesus macaques (Macaca mulatta) housed at the Tulane National Primate Research Center to assess the relative benefits of protected versus full protected contact. The study collected data in stable pairs housed first in protected contact followed by full contact. Species combined, the study found the presence of the panel was associated with lower levels of social grooming and higher levels of self-grooming, abnormal behavior, and tension-related behavior. Within species, only the protected- versus full-contact contrasts for abnormal and tension were statistically significant—and only for rhesus macaques. Results suggest that for female rhesus macaques, potential disadvantages or inconveniences of full contact should be balanced against the improved behavioral profile in comparison to protected contact. The use of protected contact among female longtailed macaques does not appear to require the same cost-benefit analysis.

Comparing the relative benefits of grooming-contact and full-contact pairing for laboratory-housed adult female Macaca fascicularis

Tactile social contact is the most effective form of environmental enrichment for promoting normal behavior in captive primates. For laboratory macaques housed indoors, pair housing is the most common method for socialization. Pairs can be housed either in full contact (FC), or in protected contact (PC). At Washington National Primate Research Center, PC is provided by grooming-contact (GC) cages whereby two partners are housed individually in adjacent cages with access to each other through widely spaced vertical bars. Grooming-contact has been used to accommodate research protocol restrictions and improve the likelihood of compatibility for various pairings, in part by enabling male–female pairs. This study compares the benefits between the two housing types by video recording 14 pairs of adult female Macaca fascicularis in four sequential housing phases following an ABBA design: baseline grooming-contact, full contact shortly after introduction, 1-month-later full contact, and after reversion to grooming-contact. Prior to this study, pairs had been housed compatibly in GC. Twelve of the 14 long-term pairs transitioned successfully to full contact and data presented exclude the two failed pairs. Allogrooming increased significantly when pairs first switched from GC to FC (P=0.018), but the effect did not last through 1-month-later FC phase suggesting that the initial improvement in affiliative behavior was a transitory novelty response that did not persist. Self-grooming significantly decreased between the first GC and first FC phases (P=0.016), likely due to redirected allogrooming. Non-contact affiliative behavior towards partner or other conspecifics in the room did not differ, nor did agonism towards partner or others in the room. Occurrence of abnormal, tension, manipulation, miscellaneous active, and inactive behaviors did not differ significantly across housing phases. Proximity measurements indicated that pairs were significantly out of arm's reach more often in protected contact than when in full contact (P≤0.02). Proportion of time spent in physical contact significantly increased between the first GC and first FC phases (P=0.002), but subsequently declined. For both FC phases, partners chose to spend about 50% of their time in the same cage. Few behavioral improvements were seen after pairs switched to full contact and no negative effects came of reversion to grooming contact. This study suggests that tactile contact provided through widely spaced bars (grooming-contact) is a viable alternative to full contact housing for adult female longtailed macaques. It provides a degree of social housing while allowing both partners choice and control, key concepts in contemporary animal welfare guidelines.

Information content of female copulation calls in wild long-tailed macaques (Macaca fascicularis)

Primates are unusual in that many females display sexual signals, such as sex skin swellings/colorations and copulation calls, without any sex role reversal. The adaptive function of these signals remains largely unclear, although it has been suggested that they provide males with information on female reproductive status. For sex skin swellings, there is increasing evidence that they represent a graded signal indicating the probability of ovulation. Data on the functional significance of copulation calls are much scarcer. To clarify the information content of such calls, we recorded copulation calls in wild long-tailed macaques (Macaca fascicularis) and analysed the structure of these calls during the ovarian cycle. Specifically, we correlated selected call parameters with the female oestrogen to progestogen ratio (obtained from faecal samples), which are known to be elevated during the female's fertile phase. In addition, we ran a general linear mixed model for these call parameters, testing factors (cycle phase, occurrence/absence of ejaculation, male dominance status, occurrence/absence of mate guarding) which potentially influence female copulation calls in primates. Our results show that copulation calls of female long-tailed macaques signal mating outcome and rank of the mating partner, but not female reproductive status. They also show for the first time on primates that copulation calls can convey information on whether a female is mate guarded or not. We suspect that the function of these calls is manipulation of male mating and mate-guarding behaviour and that in this way the degree of sperm competition and ultimately male reproductive success is influenced.

Grooming and Infant Handling Interchange in Macaca fascicularis: The Relationship Between Infant Supply and Grooming Payment

Female long-tailed macaques are attracted to infants and frequently groom mothers bearing them. Such grooming often involves the groomer contacting the infant and may be a trade of grooming for infant handling. To identify if grooming and infant handling are directly traded, I collected samples on times after female-to-mother grooming and on interactions in which a female groomed a mother and contacted her infant. I determined that grooming tended to promote an exchange with infant handling and that the supply of available infants was related to how long a female groomed a mother. Grooming interactions were longer when infants were scarce in the surrounding social environment than when they were abundant, indicating a possible supply-and-demand effect. This supports that grooming may be payment for infant handling. Grooming-infant handling interchanges tended to be unidirectional as mothers usually did not reciprocate grooming. Instead, infant contact occurred. A larger proportion of grooming-infant handling interchanges involved younger infants, but infant age did not seem to influence grooming durations. The length of female-to-mother grooming had no observable effect on handling time. Lower-ranked females groomed higher-ranked mothers and their infants longer than vice versa. Moreover, it was possible to predict up-rank grooming via supply and demand better than down-rank grooming. There was no observable influence of kinship on grooming-infant handling interchange. These results support the conclusion that grooming and infant handling may be traded. Grooming promoted infant handling, while supply and rank predicted the grooming payment a female would offer to access an infant.

Female long‐tailed macaques with scrotum‐like structure

Female long-tailed macaques (Macaca fascicularis) living in multimale and multifemale societies show a swelling and reddening of the sexual skin around the anogenital region when they approach ovulation. These swellings are limited to the base of the tail in many local populations. We recently observed another type of sexual swelling in long-tailed macaques inhabiting localities north of the Isthmus of Kra, Thailand. This swelling was located in the inguinal region in pubertal females. These swellings develop bilaterally into a globular structure, which so strongly resembles the male scrotum that it is difficult to reliably identify an individual's sex at a distance using only the standard phenotypic features of differential presence of clitoris or scrotum. The sex of the monkeys possessing the scrotum-like swelling was examined at the chromosomal and gonadal levels by determining the presence of two sex-related genes (the SRY and the AMEL), and sex-steroid hormone levels, respectively. For chromosomal sex, polymerase chain reaction (PCR)-based assays suggested the absence of the Y-linked SRY and AMEL loci but the presence of the X-linked AMEL locus in the scrotum-like monkeys, consistent with them being XX and not XY. Plasma testosterone levels of the monkeys possessing the inguinal sex skin swelling did not differ from those of ordinary females and was significantly lower than that of subadult and adult males. However, plasma estradiol levels were higher than those of both ordinary adult males and ordinary adult females. Together, the data strongly support the suggestion that these are XX females. Indeed, most of the tissue components of the scrotum-like swelling were in fact adipose cells. Upon our latest survey in Thailand, the scrotum-like swellings were observed only in long-tailed macaques inhabiting the Indochinese region, above the Isthmus of Kra. To understand whether the scrotum-like swelling is related to geographical distribution, further study is necessary.

Post-conception mating in wild long-tailed macaques ( Macaca fascicularis): Characterization, endocrine correlates and functional significance

In many anthropoid primates, mating activity is not restricted to the ovarian cycle but also occurs during pregnancy. Although it has been suggested that the main function of this post-conception mating is to confuse paternity, studies showing whether or not male primates can distinguish between the fertile phase of the conception cycle (FPCC) and the period of peak post-conception mating (peak PCM) are almost non-existent. Here, we examine whether the pattern of female sexual traits (specific sexual behaviors, sexual swelling) and female attractiveness to males differ between FPCC and peak PCM in 6 wild female long-tailed macaques. We also use fecal hormone analysis to investigate whether female traits during peak PCM are related to changes in female sex hormones. All females exhibited a distinct period of heightened mating activity around days 45–60 of gestation. During peak PCM, swelling size and frequency of female solicitations (but not reaching back) were significantly correlated with changes in the estrogen to progestogen ratio. Swelling size, frequency of female sexual behaviors and copulations and proportion of male-initiated copulations and ejaculations were not significantly different between FPCC and peak PCM. Although males spent significantly less time consorting females during peak PCM, all (particularly low-ranking and non-resident males) invested heavily in terms of reproductive costs associated with mate-guarding and mating during pregnancy. We conclude that post-conception mating in wild long-tailed macaques is not merely a by-product of endocrine changes and devoid of adaptive function. Our results more strongly support the hypothesis that it may form part of a female reproductive strategy to confuse paternity, which appears to apply particularly to low-ranking and extra-group males.

A pair choice test to identify female mating pattern relative to ovulation in longtailed macaques, Macaca fascicularis

Female mammals may exert choice for mates directly by mating selectively. Alternatively, females can mate promiscuously, allowing sperm competition and/or cryptic female choice to operate. Primate sexual behaviour is probably a compromise between conflicting male and female interests, so it may be important to examine female mating behaviour independently from male influence to better understand female mating strategies. To explore how female behaviour and ovarian cycle phase influence the choice and number of mates in female longtailed macaques, we conducted a pair-choice test where females had complete control over access to males. Subjects were six females and four males. Females were presented with a different pair of males twice a day. Each male was in an adjacent chamber. Females could enter freely and were allowed two entries per male pair. Entry and subsequent copulation with a male was defined as a choice with mating. Females saw each male every day; the males within a pair alternated in a fixed order. We related the females' mating pattern to the females' mating pattern to menstrual cycle stage and timing of ovulation, as determined from faecal progestogen profiles. Females chose and mated with males promiscuously in all periods of their menstrual cycle (prefertile, fertile and postfertile). Overall, females apportioned choices with mating and number of copulations evenly across males. In general, female preferences were not based on male dominance rank. Further investigation is needed to better understand the nature of mating preferences and the adaptive significance of promiscuity in female primates.

Social Housing of Previously Single-Caged Macaques: What Are the Options and The Risks?

AbstractA review of the scientific literature gives evidence that transferring previously single-caged adult macaques to permanent compatible pair-housing arrangements (isosexual pairs, adult/infant pairs) is associated with less risk of injury and morbidity than transferring them to permanent group-housing arrangements. Juvenile animals can readily be transferred to permanent group-housing situations without undue risks. Safe pair formation and subsequent pair-housing techniques have been developed for female and male rhesus(Macaca mulatta), stump-tailed(M. arctoides)and pig-tailed macaques(M. nemestrina)as well as for female long-tailed macaques(M. fascicularis). Pair housing does not jeopardize the animals’ physical health but it increases their behavioural health by providing them with an adequate environment to satisfy their need for social contact and social interaction.

Social Tension in Familiar and Unfamiliar Pairs of Long-Tailed Macaques

The behavioural responses of monkeys to the pairing with familiar and unfamiliar individuals were analysed in order to test whether differences in social tension were related to different patterns of affiliation. Social tension was derived from the frequency of displacement activities. Ten familiar pairs (the F group) and 20 unfamiliar pairs (the UF group) of adult female long-tailed macaques (Macaca fascicularis) were observed in a two-hour test. The UF group was divided into two subgroups on the basis of the establishment of clearcut dominance relations within the pairs (as revealed by bared-teeth displays). Unfamiliar pairs showing clearcut dominance relations (the UFa subgroup) did not differ from the F group in terms of grooming exchanged and displacement activities. Unfamiliar pairs without clearcut dominance relations (the UFb subgroup) showed less grooming and more displacement activities. A delay in the onset of allogrooming due to unresolved dominance relations was responsible for the differences in social tension between the different monkey pairs. The results of this study suggest that unfamiliarity between the monkeys is not a good predictor of social tension if the patterns of behavioural interactions between the individuals are not taken into account.

30-day oral toxicity study of l-selenomethionine in female long-tailed macaques ( Macaca fascicularis)

Twenty female long-tailed macaques received nasogastric intubation of 0–600 μg/kg-day l-selenomethionine for up to 30 consecutive days. Selenium ingestion was well tolerated at all dose levels until the second to third week of the study at which time two animals given 600 μg/kg-day died. One animal from the 300 μg/kg-day group was removed from study on Treatment Day 19 due to selenium-induced hypothermia. In some cases, administered doses were reduced at the 300 and 600 μg/kg-day levels such that the final time-weighted average doses were 0, 25, 62–117, 150, 188–203, and 300 μg/kg-day. Six animals at the 188 μg/kg-day level or greater required nonscheduled fruit and dietary supplementation to prevent their impending demise. As the dose and duration of exposure increased, the incidence of anorexia, gastrointestinal distress, mucocutaneous toxicity, and frequency of reduced body temperature also increased. A dose-dependent reduction in body weight was also observed. At the greater doses, disturbances in menstrual function were evident, and were accompanied by the absence of serum progesterone concentrations above 1.0 ng/ml, reduced luteal phase lengths, increased intermenstrual intervals, and lowered estrogen excretion. A maximum tolerated dose of 150 μg/kg-day l-selenomethionine for 30 days was identified based on mean body weight reduction, hypothermia, dermatitis, xerosis, cheilitis, disturbances in menstruation, and the necessity of dietary intervention to prevent death at doses of 188 μg/kg-day or greater.

Scramble and Contest in Feeding Competition Among Female Long-Tailed Macaques (Macaca Fascicularis)

AbstractMost previous studies of feeding competition in gregarious primates compared some average or group-level characteristic over a range of group sizes. Here an attempt is made to separate the effects of within-group scramble (the "group size" effect) and of within-group contest (the "dominance" effect) on energy expenditure and food intake in female long-tailed macaques (Macaca fascicularis). Significant or consistent scramble and contest components were demonstrated for locomotion and energy expenditure, for the presence in the main party of the group, and for birth rate. The intake of fruit or animal matter was not increased in compensation, but the intake of dispersed vegetable matter probably was. It is concluded that both components of feeding competition exist in long-tailed macaques, but that contest for food is often transferred into contest for safety. A framework is proposed to relate interspecific variation in contest effects to food distribution and group cohesion.