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The effects of three rearing conditions on biting behavior and whether early infant behavior can predict later self-biting in socially-housed rhesus macaques (Macaca mulatta) are examined. The results have shown that surrogate rearing in combination with lower levels of social contact during play might be risk factors for the later development of self-biting behavior.

Self-injurious behavior (SIB) that occurs in both human and nonhuman primate populations is tested. Results noted that SIB might persist in monkeys because they lack the ability to regulate the intensity of their biting behavior.

The investigation is to survey abnormal behavior in a large population of Rheus macaques, to characterize the relationship between stereotypies and self- injury, and to identify potential risks factors for these aberrant behaviors.

Alopecia is a ubiquitous, multifaceted problem at facilities caring for captive rhesus macaques. There is a wide range of potential etiologies for the hair loss, including compromised immune function, dermatological pathologies, and environmental factors. However, few studies have examined whether various temperamental traits affect vulnerability to develop alopecia. We examined the correlation between alopecia and temperament in 101 (51M) indoor-housed rhesus macaques at four national primate centers. We utilized a cage side version of the Human Intruder test (HIT) to assess response to four conditions: no human present (Alone), human intruder standing next to the cage without making eye contact (Profile), intruder making direct eye contact (Stare) and intruder with back turned (Back). Behavior from all videos was quantified at one facility. We used generalized linear modeling to examine the relationship between behavior on the HIT and alopecia, controlling for facility, age, and sex. There was a significant negative correlation between alopecia and various behaviors associated with an inhibited or anxious temperament, including self-directed behavior ( β = −0.15, P < 0.001) and freeze in the Profile period ( β = −0.0092, P < 0.001), and defensive behaviors ( β = −0.0094, P < 0.001) and time spent in the back of the cage in the Stare period ( β = −0.0023, P = 0.015). Individuals with an inhibited or anxious temperament had less alopecia than others. Further, there were facility differences with respect to several variables on the HIT, including defensive behavior in Stare and freeze in Profile. These results suggest that temperament can influence the development of alopecia in rhesus macaques. Our results also highlight the degree to which facility differences can affect outcomes on standardized behavioral tests. Am. J. Primatol. 79:e22504, 2017. © 2015 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Measurement of cortisol in hair provides a chronic index of hypothalamic-pituitary-adrenal (HPA) axis activity and has been applied to assessments of temperament (stable behavioral differences between individuals). However, the extent to which chronically high HPA axis activity relates to a correspondingly high degree of behavioral reactivity is as yet unknown. Therefore, the goal of the present experiment was to assess the relationship between hair cortisol and a reactive temperament. We administered the Human Intruder Test (HIT) twice to 145 (80 male) rhesus macaques ( Macaca mulatta) in order to assess behavioral reactivity. The HIT presents monkeys with an unfamiliar experimenter and is composed of a Baseline phase (no intruder) followed by three experimental phases in which the orientation of the intruder changes (Profile, Stare, Back). Behavioral responses to the test were videotaped and behaviors thought to reflect a reactive response to the intruder were scored for duration. Hair samples collected within ±1 month of the first HIT session were analyzed for cortisol by enzyme immunoassay. Subjects were assigned to three groups based on hair cortisol concentration: high, intermediate, and low cortisol phenotypes. Monkeys with the high cortisol phenotype were more reactive to the presence of the intruder than those with the low cortisol phenotype: they were more aggressive, scratched more, and spent more time in the back half of the cage. Males yawned significantly more while females spent more time immobile and in the back of the cage. Overall, monkeys with higher hair cortisol demonstrated an exaggerated response to the presence of the human intruder, supporting a relationship between high levels of chronic HPA axis activity and a reactive temperament. These results indicate that high levels of HPA axis activity, which may result from either genetic variation or environmental stress, correspond with heightened behavioral responses to a stressful experience. Am. J. Primatol. 79:e22526, 2017. © 2016 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Hair loss is common in macaque colonies. Very little is known about the relationship between psychological stress and hair loss. We initially examined alopecia and hair cortisol concentrations in 198 (89 male) rhesus macaques from three primate centers and demonstrated replicability of our previous finding that extensive alopecia (>30% hair loss) is associated with increased chronic cortisol concentrations and significantly affected by facility. A subset of these monkeys (142 of which 67 were males) were sampled twice approximately 8 months apart allowing us to examine the hypotheses that gaining hair should be associated with decreases in cortisol concentrations and vice versa. Hair loss was digitally scored using ImageJ software for the first sample. Then visual assessment was used to examine the second sample, resulting in three categories of coat condition: (i) monkeys that remained fully haired; (ii) monkeys that remained alopecic (with more than 30% hair loss); or (iii) monkeys that showed more than a 15% increase in hair. The sample size for the group that lost hair was too small to be analyzed. Consistent with our hypothesis, monkeys that gained hair showed a significant reduction in hair cortisol concentrations but this effect only held for females. Coat condition changed little across sampling periods with only 25 (11 male) monkeys showing a greater than 15% gain of hair. Twenty (7 male) monkeys remained alopecic, whereas 97 (49 males) remained fully haired. Hair cortisol was highly correlated across samples for the monkeys that retained their status (remained alopecic or retained their hair). Am. J. Primatol. 79:e22547, 2017. © 2016 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Hair eating in nonhuman primates is thought to result from a frustrated appetitive drive produced by an inappropriate diet. To investigate whether hair eating could be reduced through changes in diet, a 2-part study was conducted with a group of baboons (Papio hamadryas sp.). The 1st part involved changing to a twice-daily feeding routine, thus providing prolonged access to an appropriate food source. The 2nd part involved scattering a grain mix to encourage more foraging while maintaining a once-daily feeding routine. Changing the feeding routine unexpectedly resulted in a significant increase in hair manipulation and ingestion. Providing additional grain did not significantly decrease hair manipulation and ingestion, but several individuals did show a reduction in these behaviors. Prolonged access to biscuits and the provision of a grain mix may have failed to satisfy the urge to forage because little effort was needed for their collection prior to consumption. Although the current study failed to significantly decrease hair eating, it provides valuable insight into further avenues of research on the behavior. [ABSTRACT FROM PUBLISHER]

Abnormal behavior, ranging from motor stereotypies to self-injurious behavior, has been documented in captive nonhuman primates, with risk factors including nursery rearing, single housing, and veterinary procedures. Much of this research has focused on macaque monkeys; less is known about the extent of and risk factors for abnormal behavior in baboons. Because abnormal behavior can be indicative of poor welfare, either past or present, the purpose of this study was to survey the presence of abnormal behavior in captive baboons and to identify potential risk factors for these behaviors with an aim of prevention. Subjects were 144 baboons (119 females, 25 males) aged 3-29 (median = 9.18) years temporarily singly housed for research or clinical reasons. A 15-min focal observation was conducted on each subject using the Noldus Observer® program. Abnormal behavior was observed in 26% of the subjects, with motor stereotypy (e.g., pace, rock, swing) being the most common. Motor stereotypy was negatively associated with age when first singly housed ( P < 0.005) while self-directed behavior (e.g., hair pull, self-bite) was positively associated with the lifetime number of days singly housed ( P < 0.05) and the average number of blood draws per year ( P < 0.05). In addition, abnormal appetitive behavior was associated with being male ( P < 0.05). Although the baboons in this study exhibited relatively low levels of abnormal behavior, the risk factors for these behaviors (e.g., social restriction, routine veterinary procedures, and sex) appear to remain consistent across primate species. Am. J. Primatol. 76:355-361, 2014. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Self-injurious behaviors (SIB), such as self-biting and self-wounding, have been observed in a small percentage of captive nonhuman primates. Because rhesus monkeys that exhibit SIB also tend to be more aggressive, it was hypothesized that SIB is related to externally directed aggression and is associated with contexts in which physical contact between participants is prevented. The purpose of this study was to test the hypothesized relationship between SIB and outward aggression. Subjects were first presented with videotapes of conspecifics, scenery and a blank screen, and their behavior was recorded. Levels of salivary cortisol, an indicator of stress, were also measured before and after presentation of the videos. Although aggression increased when subjects viewed tapes containing conspecifics, neither cortisol levels nor self-biting behavior varied as a function of tape content. The subjects were then placed in two additional test situations: an empty room and the same room containing an unfamiliar conspecific. Aggression was significantly higher in the stranger condition compared to the empty room condition. The two situations yielded parallel increases in cortisol, suggesting that being alone was just as stressful as being paired with an unfamiliar conspecific. Self-biting rates were also similar in these two conditions. Thus, contrary to our prediction, increases in aggression did not correlate with increases in SIB. These results suggest that under similarly stressful conditions, SIB and externally directed aggression are unrelated. [Copyright &y& Elsevier]

Simple Summary: Social play among immature individuals has been well-documented across a wide range of mammalian species. It represents a substantial part of the daily behavioral repertoire during immature periods, and it is essential for acquiring an appropriate set of motor, cognitive, and social skills. In this study, we found that infant Tibetan macaques (Macaca thibetana) exhibited similar patterns of social play between males and females, juvenile males engaged more aggressive play than juvenile females, and juvenile females engaged more affiliative play than juvenile males. Our results provided more evidence to understand the functional differences of social play in immature nonhuman primates. Theories proposed to explain social play have centered on its function in establishing social relationships critical for adulthood, its function in developing motor skills needed to survive, and promoting cognitive development and social learning. In this study, we compared variations in social play among infant and juvenile male and female Macaca thibetana. Given that this species is characterized by female philopatry and male dispersal, we hypothesized that immature females use social play as a mechanism to develop bonds that persist through adulthood whereas immature males use play to develop social skills needed to successfully enter new groups. The results indicated that social play steadily increased during the infant period and peaked at approximately 12 months of age. There were no significant differences in the frequency or types of social play exhibited between infant males and infant females. During the juvenile period, however, social play was found to decrease with age, with males engaging in social play more frequently than juvenile females. Moreover, whereas juvenile males engaged in more aggressive forms of play, juvenile females engaged in more affiliative forms of play. In addition, juvenile females engaged in higher rates of grooming than juvenile males. These results provide evidence of sex-specific differences and imply the functional variation of social play in Tibetan macaques, with immature males using social play to develop skills needed to enter and enhanced their dominance rank in a new social group and immature females using social play to develop long-term same-sex social bonds in their natal group. [ABSTRACT FROM AUTHOR]

Simple Summary: Housing of primates in groups increases animal welfare; however, this requires management to prevent inbreeding. To this end, males are introduced into captive macaque breeding groups, mimicking the natural migration patterns of these primates. However, such male introductions can be risky and unsuccessful. The procedure developed by the Biomedical Primate Research Centre (BPRC), Rijswijk, the Netherlands, to introduce male rhesus macaques (Macaca mulatta) into naturalistic social groups without a breeding male achieves relatively high success rates. Males are stepwise familiarized with and introduced to their new group, while all interactions between the new male and the resident females are closely monitored. Monitoring the behaviour of the resident females and their new male during all stages of the introduction provides crucial information as to whether or not it is safe to proceed. Flow diagrams identify which decisions must be made during the introduction period. The BPRC introduction procedure is widely applicable to primates with natural male migration. Following this procedure may improve the management of captive primate groups in any housing facility worldwide. Altogether, careful introduction management can minimize the risk associated with male introductions and enhance the welfare of captive primates. Male introductions into captive primate breeding groups can be risky and unsuccessful. However, they are necessary to prevent inbreeding in naturalistic breeding groups. The procedure used to introduce new individuals may affect the success and influence the risks associated with group introductions. At the Biomedical Primate Research Centre (BPRC) in Rijswijk, the Netherlands, male rhesus macaque (Macaca mulatta) introductions into naturalistic social groups with a matrilineal structure and without a breeding male achieve relatively high success rates. This paper describes the male introduction procedure used at the BPRC. Males are stepwise familiarized with and introduced to their new group, while all interactions between the new male and the resident females are closely monitored. Monitoring the behaviour of the resident females and their new male during all stages of the introduction provides crucial information as to whether or not it is safe to proceed. The BPRC introduction procedure is widely applicable and may improve the management of captive primate groups in any housing facility worldwide. Thus, the careful introduction management can minimize the risk associated with male introductions and enhance the welfare of captive primates. [ABSTRACT FROM AUTHOR]

Effective environmental enrichment is used by animals, promotes species-typical behavior, and decreases abnormal behavior. Porches attached to the front of an animal's cage provide additional space, perching opportunities, and a better view of the surroundings. Here we assessed the effectiveness of porches as a form of enrichment and identified characteristics of the animals most likely to use the porches. We videorecorded and scored the behavior of 18 (9 male, 9 female) singly housed cynomolgus macaques (Macaca fascicularis) during 3 observation intervals (15 min each) the week before, during, and after exposure to the porches. Changes in abnormal and tension-related behaviors (pacing, yawning, scratching) and speciestypical behaviors were compared across the 3 wk of observation. Novel object temperament tests were performed before and after the study. During observation periods, subjects spent an average of 75% of time in the porch. No changes in pacing or tension-related behaviors occurred, but activity decreased during and after porch exposure, rest increased during the porch exposure, and consumption decreased afterward. Eight subjects were categorized as having a bold temperament, and the remaining 10 subjects had an intermediate temperament. Sex and a temperament×cage location interaction were predictors of porch usage. Males used the porches more than did females, and those with an intermediate temperament were less likely to use the porches when they were located in the lower cages. Porches are beneficial in that they are used for extensive periods of time, but the benefits can vary according to the individual animal.

Alopecia has been reported to occur in several species of captive NHP. Much of this research has focused on macaque monkeys; whether other primate species such as baboons are affected similarly is unknown. Because alopecia can be a focus of inspectors and a possible marker of wellbeing, the purpose of the current study was to survey the occurrence of alopecia in 2 baboon populations and to identify potential risk factors. Subjects were 262 group-housed and 279 corral-housed baboons. Alopecia was assessed cage-side (group-housed) and on sedated animals (corral-housed). Although alopecia was mild in both populations, there were significant effects of season and sex. Alopecia was greater in the winter (group-housed) and the fall (corral-housed) and in female baboons. In addition, the group-housed baboons showed a significant negative effect of age and a lesser effect of group size on alopecia. These results demonstrate that variables other than those associated with animal management practices can affect hair loss in baboons.

Hair loss is a common problem in captive macaque colonies. A potential factor is the possible influence of stressful environments in the development of hair loss. We examined the relationship between hair loss and chronic hypothalamic-pituitary-adrenal (HPA) axis activity by measuring cortisol in hair. Adult male and female rhesus macaques housed at 3 primate facilities in the United States were screened for degree of hair loss and observed for evidence of hair-plucking behavior. Hair samples and photographic data were obtained from 99 subjects, none of which were hair-pluckers. Macaques with greater than 30% hair loss (alopecia group) showed higher concentrations of hair cortisol than did those with less than 5% hair loss (control group), a finding that was unrelated to age, body weight, or the month in which the sample was collected. Hair loss scores were positively correlated with hair cortisol levels across all monkeys and within the alopecic group alone. In addition, the strong relationship between hair cortisol and alopecia was noted in 2 but not the third facility. Friction with cage surfaces appeared to contribute to hair loss in 18 monkeys. These findings suggest that stress may be one of several factors related to hair loss in some captive nonhuman primates, although whether this relationship is causal or merely correlational is unclear. Moreover, the source of the additional cortisol in the hair of alopecic monkeys (that is, from the circulation or from local synthesis in the skin) remains to be determined.

Alopecia is a common problem in rhesus macaque colonies. A possible cause of this condition is hair-pulling; however the true relationship between hair-pulling and alopecia is unknown. The purpose of this study was to examine the relationship between hair loss and hair-pulling in 1258 rhesus macaques housed in 4 primate colonies across the United States. Alopecia levels ranged from 34.3% to 86.5% (mean, 49.3%) at the primate facilities. At facilities reporting a sex-associated difference, more female macaques were reported to exhibit alopecia than were males. In contrast, more males were reported to hair-pull. Animals reported to hair-pull were significantly more likely to have some amount of alopecia, but rates of hair-pulling were substantially lower than rates of alopecia, ranging from 0.6% to 20.5% (mean, 7.7%) of the populations. These results further demonstrate that hair-pulling plays only a small role in alopecia in rhesus macaques.

Self-injurious behavior (SIB) is a serious behavioral condition that afflicts millions of individuals in the United States alone. The underlying factors contributing to the development of self-injury in people are poorly understood, and existing treatment strategies for this condition are limited. A low but persistent percentage of socially reared individually housed rhesus monkeys also spontaneously develop SIB. Data obtained from colony records suggest that the risk of developing SIB in socially reared rhesus monkeys is heightened by adverse early experience and subsequent stress exposure. The present review summarizes the physiological and neurochemical findings obtained in this nonhuman primate model of SIB, focusing on monoamine neurotransmitters, neuropeptides, and neuroendocrine systems. The results indicate that monkeys with SIB exhibit long-lasting disturbances in central and peripheral opioid and stress response systems, which lead to increased levels of anxiety. Based on these findings, we propose an integrated developmental-neurochemical hypothesis in which SIB arises from adverse life events in a subset of vulnerable monkeys, is maintained by a persisting dysregulation of several neurochemical and physiological systems, and functions to periodically reduce anxiety when the levels of anxiety become excessive. Implications of this hypothesis for understanding self-injury in patients with borderline personality disorder and members of the general population are discussed.