Copper,iron, manganese,and zinc content of hair from two populations of rhesus monkeys

The concentrations of the elements copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn) in hair of caged (in Maryland) and freeranging (in Puerto Rico) rhesus monkey populations were determined. Significant chronological age-related decreases were evident for the trace elements Mn and Zn in both populations (P<0.01) and for Cu and Fe in free-ranging monkeys (P<0.005). The only overall gender difference was higher hair Mn concentration in freeranging males than in females (P<0.03). There were no significant differences in hair Cu, Fe, or Mn related to pregnancy status. Hair Zn was lower in samples from pregnant than from nonpregnant monkeys from the caged monkeys (P≤0.05), but did not differe in the freeranging monkeys. Comparison of the two populations revealed that hair Zn levels were significantly higher in caged vs free-ranging animals (P<0.001). We attribute this higher hair Zn in the caged monkeys to contact and ingestion of Zn from their galvanized enclosures. Hair iron levels were significantly higher (P<0.001) in free-ranging monkeys, possibly as a result of Fe-rich soil ingestion from their environment. These data support continued investigation of the use of hair as an indicator of the exposure of large groups or populations to potentially high levels of specific minerals, and the use of nonhuman primates as models for the study of trace element deficiency and/or toxicity in humans. Prelliminary reports of portions of these data were presented at the 69th Annual Meeting of the Federation of American Societies for Experimental Biology, April 1982, New Orleans, LA (B. M. Marriott, J. C. Smith, R. Jacobs, A. O. Jones, M. J. Kessler, and R. Rawlins,Fed. Proc. 41:770, [1982]) and in a symposium at the 6th Annual Meeting of the American Society of Primatologists, 1983, East Lansing, MI (B. Marriott, J. C. Smith, R. Jacobs, A. O. Lee Jones, R. Rawlins, and M. J. Kessler,Am. J. Primatol. 4(3): 157 [1983]; B. Marriott, J. C. Smith, Jr., R. M. Jacobs, A. O. Lee Jones, R. Rawlins, and M. J. Kessler, inThe Cayo Santiago Macaques, R. Rawlins and M. J. Kessler, eds., SUNY Press, Albany, NY, pp. 219–231 [1986]).     

Group fission in free-ranging rhesus monkeys of Tughlaqabad,Northern India

A population of rhesus monkeys (Macaca mulatta)at Tughlaqabad on the southeastern outskirts of New Delhi has grown rapidly in the past 4 years, and the largest group (Group A) has given rise to three smaller groups. Fissioning, or new group formation, was not consistently associated with any particular season of the year or stage of the reproductive cycle, but it did occur in each case when the parent group reached approximately 120 monkeys. The fissioning process was not preceded or accompanied by unusual aggressive behavior. It occurred quietly and appeared to be a loss of cohesion within the large group by which a subgroup achieved behavioral and spatial independence. Some aggressive interactions did occur following each fission when the new group approached or attempted to reenter the parent group. Each newly formed group was subordinate to the parent group and all other groups in the population.     

Subjective assessment of reactivity level and personality traits of rhesus monkeys

The purposes of this study are to determine whether subjective assessment of reactivity level in rhesus macaques, between 1 and 14 years old, is related to assessment of personality traits and whether a configuration of personality traits most salient for assessment of reactivity can be defined. Results indicate that subjective assessment of reactivity is complementary to that of personality traits. Interrater reliability and convergent validity are established. Principal-component and discriminant analyses of the present data show that 10 personality traits can assign all' subjects to reactivity level, but as few as 3 traits may be sufficient.     

Climate and reproductive seasonality in two free-ranging island populations of rhesus macaques (Macaca mulatto)

We gathered data over a 3-year period (1988–1990) on two free-ranging, island populations of rhesus macaques (Macaca mulatta)to test hypotheses concerning birth seasonal asynchrony and the relationship between climate and reproductive seasonality. Rhesus macaques from Kashmir, India, were translocated to Key Lois in 1973 and from Key Lois to Raccoon Key in 1978. Both sites are low-lying mangrove islands in the Florida Keys. Floral diversity and abundance are greater on Raccoon Key than on Key Lois. Average maximal and minimal temperatures per month did not vary significantly between Raccoon Key and Key Lois over the 3-year period. Average minimal temperatures per month on Key Lois, but not Raccoon Key, varied significantly between years. There were no significant variations in either the amount or the dates of rainfall over the 3-year period for the study area. A combined total of 1524 births was recorded for Raccoon Key (N = 879) and Key Lois (N =645). The birth season on Raccoon Key began 6 weeks earlier than on Key Lois. Births were associated with warmer, rainier months on both islands. Conceptions were associated with cooler, drier months at both study sites. No significant correlations were found between the date of the onset of the summer rains and either median conception or median birth dates on Raccoon Key or Key Lois. Our results do not substantiate the hypothesis that the onset of rainfall, within the temporal period set by photoperiod, regulates seasonal reproduction in rhesus macaques. We suggest that reproductive seasonality in the study populations may be influenced by a variety of factors.     

Atretogenic action of estrogen in rhesus monkeys: Effects of repeated treatment

The effects of 17β-estradiol (E₂), administered in Silastic capsules for 24 hours at intervals of 10 or 14 days, on follicular development and menstrual cycle characteristics were studied in 13 rhesus monkeys. In seven monkeys receiving E₂ at l0-day intervals for 50 treatment periods, new follicles frequently developed between treatments but usually regressed. In seven instances, the follicles persisted longer than expected but were steroidogenically suppressed and regressed spontaneously. Ovulation occurred in only two instances. In six monkeys receiving E₂ at 14-day intervals, new follicles developed regularly, with seven ovulations occurring in 37 treatment periods. A persistent anovulatory follicle was noted in only one instance. Menstruation occurred with equal frequency, and the interval from treatment to onset of menstruation was not significantly different regardless of treatment or the occurrence of ovulation; the intervals between menstruation approximated those of normal menstrual cycles. In general, following termination of treatment, menstrual cycles returned to normal quickly. These data indicate that E₂ administered intermittently at 10-day intervals effectively suppresses ovulation, and they provide new insight into the actions of E₂ on folliculogenesis in primates.     

A ten-month study of endogenous testosterone levels and behaviour in outdoor-living female rhesus monkeys (Macaca mulatta)

Endogenous testosterone levels were measured in association with sexual, aggressive, and social/affiliative behaviors in 11 outdoor-housed female rhesus monkeys over a ten-month period. Several behaviors (sex directed toward the male, sex received from the male, aggression directed toward the male, submission directed toward the male, submission directed toward the female, and groom another female) were significantly (p<0.05) positively correlated with testosterone in from one to five females. No trends were strong enough across all females to suggest that any of these correlations have species-wide significance. Factor analysis revealed clearcut clusters of behaviors, but elevations in testosterone were not strongly associated with any of these clusters. It is concluded that endogenous testosterone levels have little measurable effect on overt behavior in female rhesus monkeys.     

Geophagy amongst rhesus macaques on Cayo Santiago,Puerto Rico

Soil mining and eating (geophagy) behavior of rhesus macaques (Macaca mulatta) on Cayo Santiago, Puerto Rico, is described and assessed with respect to the chemical, geochemical, and mineralogical composition of the ingested materials. The samples forming the uneaten (control) and eaten (matrix and blocky) groups of soils come from the top and flanks of a marine terrace underlain with volcanic tuff on Cayo Santiago, off the east shore of Puerto Rico. Both the uneaten and geophagy samples were analyzed to determine particle size distributions, clay and primary mineralogy, and soil chemical and geochemical compositions. Primary minerals such as orthoclase and plagioclase feldspar in the clay fraction is higher in the control group than in the ingested samples. Both the control and matrix plus blocky samples have moderate to abundant amounts of kaolinite and halloysite (both silicon:aluminum = 1:1 type clay minerals) that may be important as a stimulus to geophagy behavior. The pH, total salts, and phosphorus levels in both the control and geophagy samples show considerable overlap with little clear indication of causal factors. Analysis of the geochemical data showed no clear cut elemental differences to suggest elemental supplementation as a possible explanation for mining and eating of tropical soil. It is possible that rhesus macaques ingest clay to obtain kaolinite/halloysite minerals which may alter the taste of their provided food, and may act as pharmaceutical agents to alleviate intestinal ailments such as diarrhea.     

Sterilization and its behavioral effects on free-ranging female rhesus monkeys (Macaca mulatta).

In order to control population growth rates, a decision was made to sterilize most of the free-ranging, wild rhesus macaque females of Silver Springs, Florida. Between October 1987 and March 1988, the five females who had been sterilized and released in the fall of 1986 were matched with five intact females in a behavioral study. While there were differences between the behaviors of the sterilized and intact females, the differences can be attributed more to differences in age, rank, and other factors than to the sterilization. Clinical data collected and reported on the monkeys is unremarkable.     

Maternal rejection and infant play in rhesus monkey infants

In five-minute records in which they were rejected by their mothers, passive preventions of nipple access, 11- to 15-week-old group-living rhesus monkey infants (Macaca mulatta) initiated fewer playful conctacts with others relative to the other kinds of social contact they initiated, while their overall rates of initiating social contacts may not have been reduced. Whether acts of maternal rejection are costly and distressing to the infant may depend on the nature of the social companions available for it and until more is known of the context of such acts, hypothesis about weaning conflict will be difficult to test in detail.     

Feeding habits of the rhesus monkeys (Macaca mulatta) of Jaipur and Galta,India

Between September 1987 and May 1988, the time budgets of two groups of rhesus monkeys were investigated. One group inhabited an old Observatory which is now a tourist attraction in the center of Jaipur, India. The other group lived in a hilly forest/temple complex on the outskirts of Jaipur known as Galta. Because it was believed that the monkeys of these two different areas ate different proportions of natural and provisioned food, it was expected that they would have different time budgets. To determine differences in time budgets, a combination of census taking and 10-minute interval scan samples were used to collect comparative data. The analysis of the data revealed that there were differences in the time budgets of the two groups — the Observatory monkeys foraged more, moved less, engaged in fewer aggressive acts, and slept less during the day than the Galta group. These differences are mainly attributed to the 1984–1987 drought, site differences in the variety of natural food resources, and the manner in which the monkeys are provisioned.     

Varying responses to feeding competition in a group of rhesus monkeys (Macaca mulatta)

The behaviour of members of a group of rhesus monkeys was observed in experimentally created, competitive feeding situations. Socially dominant members of the group tended to start eating before lower-ranking subjects, and generally ate more. Dominants sometimes used aggression to control access to food, but overall, intermediate-ranking monkeys were involved in most agonistic episodes. Non-dominant subjects improved their feeding performance when food was presented in three piles rather than one pile, often by snatching food and consuming it away from the pile. These general patterns were less evident when realistic snake models were placed on some of the food piles. Feeding was disrupted by the presence of snakes, but notably, subordinates risked feeding in these conditions. Piles containing preferred foods and snakes were eaten from, but a low-preference food (carrot) under snakes went untouched by all subjects. The results suggest that group-members evaluate potential risks and benefits of competing for a restricted resource, and that dominance status, while an important factor, is only one element in the equation.     

Live birthrates in two free-ranging rhesus breeding colonies in the Florida keys

The present paper provides an analysis of reproductive data derived from 1,265 adult female rhesus monkeys (Macaca mulatta), including 570 animals 13 years old and older. The data were collected during a partial census of two provisioned but free-ranging rhesus populations in the Florida Keys. Within both colonies, live birthrates were found to increase sharply among females 4–7 years old and to decline linearly among females 7–17 years of age. These data do not support the suggestion byAnderson (1986) that decline in fertility among nonhuman primate females is primarily the result of deteriorating health rather than ageper se.     

Responses of foster-mothers and troop members to adopted newborns in a captive group of rhesus monkeys

Two rhesus monkey males and two females, born to females caged singly, were exchanged with same-sex infants born to females in a large troop which was held in an enclosure in a different building. The ages of the infants were between 24 and 120 hr. The selected foster mothers (FMs) immediately accepted the foreign infants, allowed them to suckle and treated them as their own offspring. Compared with interactions with previous offspring, the FMs initially tended to be more possessive and restrictive of their foster infants: generally they took longer before they allowed the infants to sit at a distance from them and more readily retrieved them. The foster infants tended to be more active (‘fidgety’) than natural (control) offspring born to the troop. Non-related members of the troop, differentiated between foster and control groups. These troop animals more frequently approached and sat in proximity, often in fur-contact with, touched, groomed, and lipsmacked to, foster infants than control infants. The attractiveness of the fostered infants seemed to be slightly associated with the FMs' dominance rank. The foster infants were therefore viewed by others as having assumed the role afforded by the FMs' rank. Thus both FMs and other troop members recognized the unfamiliarity and novelty of the foster infant but the infants were still accepted into the group. We suggest that the different treatment of the foster infants by the troop may have consequences on the infants' future social development.     

Confirmatory factor analysis of personality structure in adult male rhesus monkeys (Macaca mulatta)

Reports from different laboratories have suggested that nonhuman primates have somewhat similar dimensions of personality. To date, however, no attempts have been made to statistically replicate a specific factor structure. In the present report, two independent observers recorded the behavior of 58 adult male rhesus monkeys, and then rated the animals with the use of a 50-item personality instrument. A confirmatory factor analysis (CFA) of the ratings resulted in the replication of a previously described four-factor personality structure [Maninger et al., American Journal of Primatology 61:73-83, 2003]. The first two dimensions-Sociability and Confidence-showed strong loadings and are similar to Affiliation and Agency dimensions in humans. The remaining dimensions-Equability and Irritability-were less clear, and it is possible that additional traits will have to be identified before a more robust structure can be established for these dimensions.     

Comparison between the diameter of hair cross-sections and the thickness of the enclosed hairs in Japanese monkeys (Macaca fuscata fuscata)

The thickness of hairs from Japanese monkeys was measured by enclosing the hairs on slide glasses with balsam. Nine monkeys were used for the study. Forty to 69 hairs from the back were examined per head. High correlations between the thickness of the enclosed hairs and the diameter of cross-sections were obtained in all monkeys. In the Japanese monkey, therefore, it is considered possible to utilize enclosed hairs for measuring the thickness without preparing cross-sections. Moreover, the medullae of which the air layers are strongly related to thermoregulation, were readily observed in the enclosed hairs.     

Infant-directed behavior in young rhesus monkeys: Sex differences and effects of prenatal androgens

Young (3–4 years old) laboratory-reared rhesus monkeys were observed in five 15-minute tests with 1–15-day-old infants. Males and females were equally likely to investigate infants. Females communicated more with infants by grin-lipsmacking and gurgling–-gestures that were not shown by any males. More females presented the ventrum to infants than did males. Females contacted infants more than did males by grooming, crouching over, and having full body contact with them. To see whether prenatal androgens produced the male pattern of response, we conducted similar tests with pseudohermaphrodites (prenatally androgenized genetic females) and neonatally castrated males. On most sexually dimorphic behaviors, pseudohermaphrodites behaved more like females than like males. Castrated males, like females and pseudohermaphrodites, crouched over infants more than did intact males. Castrated males differed from females only on one infant-directed response, the grin-lipsmack. These comparisons showed that defeminization of the repertoire of infant-directed responses was measurable only in intact males. We conclude accordingly that prenatal androgens alone are not responsible for defeminization of this repertoire and that a contribution from postnatal androgens is likely to be necessary.     

Sexual behavior in aging male rhesus macaques: Effects of test duration on sexual performance

The sexual behavior displayed by nine old (20-year and older) rhesus (Macaca mulatta) males in 10-min tests was compared to that displayed in 1-hr tests. The tests were part of a long-term study on the decline in male sexual activity that accompanies old age. The males were paired with 10 ovariectomized, estrogentreated females in two blocks of 10 tests; each male was tested once with each female in each test block. The percentages of males that achieved intromissions and ejaculated in the two test blocks were the same (P < 0.05). Although the percentage of tests in which males displayed these behaviors was higher in the longer-test block (P > 0.05), there was a significant positive correlation of performance in 10-min tests with performance in 1-hr tests. Assuming a random distribution of contacting, mounting, intromission, and ejaculation throughout the hour, we would have predicted a significantly lower number of these behaviors in the first 10 min of the 1-hr tests than we actually observed. The mean percentages of 1-hr tests with contacting, mounting, intromission, and ejaculation was significantly lower than that of 10-min tests conducted with the same males 11 years earlier. Thus, the decline in sexual performance was not an artifact of the limited (10-min) test duration.     

Effects of early experience on the behaviour of yearling rhesus monkeys (Macaca mulatta) in the presence of a strange object: classification and correlation approaches

Special techniques are needed to help us understand the long-term effects of infants' experiences of their relationships with their mothers, especially when direct experimental control of the interaction between mother and young is impossible, or could distort their relationship. A classification approach is developed to show how outcomes in individuals can be predicted from their earlier experiences and characteristics. Four-week-old rhesus monkey infants' characteristic levels of enterprise persisted through their first year, but could be reduced in certain individuals who had been kept off their mothers by high rates of early maternal rejection. Correlational approaches are difficult to interpret when they fail to confirm simple effects of experience or of individual characteristics, because they are based on groups not individuals, and because certain individuals can affect the values of correlation coefficients in ways that cannot be specified without using a classification approach. The possible effects on correlation coefficients of inconsistent individuals, and of being unable to specify which infants respond in which ways to relevant variables were discussed.