Blood values of free-ranging patas monkeys (Erythrocebus patas)

Free-ranging patas monkeys (Erythrocebus patas) from El Guayacán island, Puerto Rico, were surveyed to establish values for the hemogram, serum biochemicals, calcium, and phosphorus. Results were tabulated for males and nonpregnant/nonlactating, pregnant, and lactating females. A summary of blood values from previous studies on captive patas monkeys was also tabulated for comparison.     

Influence of age,sex, and caging on joint mobility in the patas monkey (Erythrocebus patas)

Normal range of joint mobility in the extremities of the patas monkey, Erythrocebus patas, was established for a free-ranging colony of 64 animals at La Parguera, Puerto Rico (Caribbean Primate Research Center). Eighty-five animals that had been caged (30″ × 30″ cages) for up to 5 years were used for comparison. Passive joint mobility of anesthetized animals was measured with a goniometer. Nine parameters (five on the forelimb and four on the hindlimb) were measured on each animal. The data were sorted into subsets according to the animal's age, sex, place of birth, and type of confinement, if any. The number of animals in each subset was recorded and the mean (in degrees) and standard deviation for each parameter were calculated. A P?0.05 on two-tailed Student's t-tests was considered significant. Comparisons between free-ranging males and females showed significant differences in one or two parameters for all age groups. A cross-sectional sample of free-ranging animals of both sexes showed that significant changes in joint mobility occurred only in the first 18 months of life. Joint mobility of all caged animals, however, was highly variable, and even between the more mature animals there were significant differences in several parameters. Almost all comparisons of subsets of the same age and sex showed significant differences between caged and free-ranging animals in at least one parameter. When the caged animals were laboratory-born, however, these differences were significant in five out of nine parameters. The results suggest that, although caging itself affects joint mobility, the age of first confinement may have an even greater effect than the length of the confinement.     

Color changes in the haircoat of patas monkeys (Erythrocebus patas)

Caged patas monkeys were evaluated monthly to determine changes in the color of their hair during infancy, adolescence, pregnancy and lactation. From birth until 3 months of age the facial and anterior crown hairs were short, sparse, and completely black. The body fur was a fine, short, fawn-colored hair mixed with longer black hairs which produced a black-tipped effect. During the second 3 months of life the body fur and anterior crown fur became coarser, longer, and changed to a red-brown color. The facial hairs thickened and became longer, but remained totally black. A thin line of black hairs outlined the brow and temple. The black chin hairs were gradually replaced by white from 7 to 24 months of age, and the upper lip hairs changed from black to white during the second year of life. Color changes related to pregnancy and lactation were confined to the nosepatch, cheek, and browline hair. The nosepatch and cheek hair changed from black or grey to completely white, and the browline faded to the approximate color of the body fur. These changes began approximately at the end of the second trimester of pregnancy, maximized during the third month of lactation, began to darken 1 to 2 months later, and returned completely to the black, nonpregnant colors approximately 1 year postpartum. In one nonlactating female, the darkening was delayed until 500 days postpartum and in one female ovariectomized in the light color phase, the darkening was complete 200 days later. The cause of these changes is believed to be hormonal, resulting from altered endocrine function during maturation and pregnancy, which may alter melanocyte stimulating hormone activity.     

Reproductive performance of a laboratory breeding colony of patas monkeys (Erythrocebus patas)

Reproductive statistics were gathered over a 5½-year period on a colony of Erythrocebus patas. Pregnancies occurred throughout the year under laboratory conditions with a suggestion of a mating peak in the late fall and early winter. Menstrual cycles were monitored and found to average 30.6 days in length. Maximal vaginal cornification occured on day 15 of the cycle suggesting a midcycle ovulation. However, production of timed-mated pregnancies indicated ovulation occurred earlier and that breeding on days 10, 11, and 12 after menstruation was more likely to result in pregnancy. The gestation length was found to average 167.2 days in 142 harem-bred females and 167.5 days in 11 timed-mated pregnancies. Sixty-two percent of all pregnancies resulted in live births; 28% of the conceptions terminated with in-utero death of the fetus. Stillborn infants were delivered in 9% of the pregnancies. Infant mortality during the first 6 months of life was 10.2%. Females raised in the colony conceived their first offspring at approximately 3 years of age and males were able to sire infants at 3 years and 8 months.     

Patterns of mating among male patas monkeys (Erythrocebus patas) in Kenya

An habituated group of wild patas monkeys was observed in Kenya for 550 h in 1984. Observations were made primarily during an interval that, as previous studies at the same site had demonstrated, coincided with the annual mating and conception periods. Earlier field studies of patas at other sites had reported that heterosexual patas groups had only a single resident adult male and that mating was harem-polygynous. At the Kenya site, by contrast, as many as six males were simultaneously resident and mated in the group during the conception period. Males adopted a variety of tactics to gain access to receptive females, ranging from opportunistic mating to attempts at sequestration that resembled consort behavior in other cercopithecoids such as savanna baboons and rhesus macaques. Aggressive competition for access to females took place among the males, although the number of completed copulations per male did not bear a positive relation to agonistic dominance rank. For patas monkeys, harem polygyny is only one available option within an overall mating system that is best described as a form of promiscuous polygyny, especially during periods when conception is most likely.     

Despotic wild patas monkeys (Erythrocebus patas) in Kala Maloue, Cameroon

The socio-ecological model predicts that the quality, distribution, and patch size of food resources determines the dominance hierarchy of female monkeys based on the type of food competition they experience. Comparative studies of closely related species have evaluated the socio-ecological model and confirmed its validity. For example, female patas monkeys in Laikipia, Kenya, form a nonlinear and unstable dominance hierarchy (i.e., egalitarian), whereas females of sympatric, closely related savannah monkeys form a linear and stable dominance hierarchy (i.e., despotic), in accordance with the model's predictions of the characteristics of food resources. I compared agonistic interactions involving food between patas monkeys (Erythrocebus patas) and sympatric savannah monkeys (Cercopithecus aethiops) in Kala Maloue, Cameroon. I found linear dominance hierarchies not only in savannah monkeys, but also in patas monkeys in Kala Maloue. The rates of agonistic interactions during feeding between patas monkeys were equivalent to those between savannah monkeys in Kala Maloue; further, these rates were significantly higher than those of both Laikipia patas and savannah monkeys. The results imply that patas monkeys in Kala Maloue are not egalitarian, but are despotic, similar to savannah monkeys. Disparity in the dominance hierarchies of patas monkeys between Kala Maloue and Laikipia were attributable to the differences in the characteristics of food resources. Although patas monkeys in Laikipia subsist on small and dispersed food resources within a high-density area, those in Kala Maloue subsisted on food resources that were clumped in intermediate-sized patches within a low-density area. This study shows that the socio-ecological model is applicable not only for interspecific comparisons but also for intraspecific comparisons.     

Distribution and abundance of patas monkeys (Erythrocebus patas) in Laikipia, Kenya, 1979-2004

Patas monkeys may be especially vulnerable to local extinction because they live in relatively small, female-philopatric groups at low densities and are strongly polygynous. We assessed a patas monkey population in Kenya's 9,700 km(2) Laikipia District over 25 years, using data collected in 1979-1981 and 1992-2004. The data were based on intensive observations of three study groups, "on the ground" counts, and surveys of Laikipia residents. In 1979-1981, a minimum of 415 patas monkeys lived in 14-15 groups. By 2000, the best estimate suggested 310-445 patas monkeys living in 13-17 groups over a greater surveyed area, suggesting that patas monkeys in Laikipia may have undergone a slight decline in numbers over time. Their distribution, however, was similar over time. The relative stability of this population has likely been the result of beneficial co-existence with large-scale cattle ranching. Outside Laikipia, substantial habitat alteration from rising human populations has coincided with the near disappearance of patas monkeys where they were previously more numerous. The small population in Laikipia, probably the largest remaining in Kenya, may therefore be critical to the continued existence of patas monkeys in that country and may be dependent on maintenance of large-scale ranches. Such land use provides patas monkeys with water and broad expanses of Acacia drepanolobium woodlands, the habitat to which patas are restricted in Laikipia.     

The ecology of the introduced patas monkey (Erythrocebus patas) population of Southwestern Puerto Rico

This paper presents the results of a study on the introduced, free-ranging patas monkey population of Southwestern Puerto Rico (SWPR). It describes information on the population size, social group composition, diet, daily ranging patterns, and patas home range during a 3 year period. The patas monkey population in the study area consisted of approximately 120 individuals in four heterosexual groups and several all-male bands. Within their home ranges (26.8 km²), the population density was 4.47 individuals/km². Home range size among the population's four heterosexual groups varied from 3.72 km² to 15.39 km², and minimum daily distance traveled ranged from 0.8–2.0 km. In general, the social structure and mating system of this population parallels what has been described for African populations. However, habitat use, ranging behavior, and the quality of intergroup interactions suggests that patas of this population exhibit territorial behavior. Am. J. Primatol. 45:351–365, 1998. © 1998 Wiley-Liss, Inc.     

Life-history parameters of a wild group of West African patas monkeys (Erythrocebus patas patas)

Based on long-term, although intermittent, observations (2 years 4 months of 14 years), we present data on birth seasonality, age at first birth, interbirth intervals, mortality rates, age at first emigration, and population change of a wild population of West African patas monkeys (Etythrocebus patas patas) in northern Cameroon. Birth season was from the end of December until the middle of February, corresponding to the mid-dry season. In spite of large body size, the patas females had the earliest age at first birth (36.5 monthsold) and the shortest interbirth intervals (12 months) compared to the closely related wild forest guenons. Age at first emigration of the males was considered to occur between 2.5 and 4.5 years. The group size of the focal group drastically decreased between 1984 and 1987, and steadily increased until 1994, then decreased again in 1997. The neighboring group also showed a similar trend in group size. The population decreases were likely to be caused by drought over 3 years. Annual crude adult mortality rate was 4% during population increase periods (PIP) between 1987 and 1994. It rose to 22% during all the periods (AP), including drought over 3 years. Despite their smaller body size, the rate of the wild forest guenons (Cercopithecus mitis) (4%) was the same and much lower than those of the patas during PIP and AP, respectively. The annual average juvenile mortality rate was 13% during PIP and it also rose to 37% during AP. That of wild forest guenons (C. ascanius) (10–12%) was a little lower and much lower than those of the patas during PIP and AP, respectively. These findings were consistent with Charnov's theoretical model of mammalian life-history evolution in that patas with high adult and juvenile mortality showed early and frequent reproduction in spite of large body size. Charnov also considered high adult mortality as a selective force and high juvenile mortality as a density-dependent consequence of high fecundity. Our results support the former but not the latter research findings.     

Mating strategy and reproductive success of male patas monkeys (Erythrocebus patas)

Mating behavior and paternity of offspring of wild patas monkeys were studied at Kala Maloue National Park, Cameroon. Observation of patas groups over three years revealed that multi-male situations occurred after takeover of the position of a resident male. Direct observation of behavior showed that resident males (harem males) occupied only 31% of mating in multi-male situations and 100% in one-male situations. DNA-typing revealed that resident males sired two of four of infants in the one-male situation and four of five in the multi-male situation. Under the two years cycle of the one-male situation and the multi-male situation, calculation shows that resident males sired more offspring than sneakers both in observation and paternity testing. Sneak mating occurred during both one-male and multi-male situations, and resident males performed compensatory mating, with dilution of sneaker sperm; these activities explain the discrepancy found between observation of mating and results of paternity discrimination.     

Allomaternal behavior in a group of free-ranging patas monkeys

A free-ranging group of patas monkeys (Erythrocebus patas) containing 18 individually identifiable adult females was observed for approximately 400 hours, equally distributed over two two-month periods corresponding to the breeding and birth seasons, at the La Parguera facility of the Caribbean Primate Research Center. The large number of infants born in the spring and early summer (n = 14) allowed for detailed observations of alloparental behaviors, with a focus on allomothering by the adult females. Seven types of alloparental behaviors were recorded: contact, nuzzling, grooming, agonism, close visual inspection, attempted kidnapping, and kidnapping. Adult females emitted the vast majority of allomaternal behavior, the patterning and frequency of which closely resembled the patterning and frequency of inter-adult female social grooming. Relative dominance status of the participants did not consistently predict the directionality of allomothering. The most commonly observed allomaternal behaviors were contact and nuzzling, which are primarily affiliative behaviors; agonism was rare. Successful kidnapping occurred eight times. Immature monkeys (n = 22) emitted an additional 32 alloparental acts. A propensity towards allomothering by experienced females would be most beneficial to patas infants due to the patas' tendency towards dispersed foraging and rapid flight in the presence of danger. It is possible that direct competition with groups of rhesus macaques for available resources on the island served as a proximal cause for the allomothering observed in this patas group.     

Interspecific and temporal variation of ant species within Acacia drepanolobium ant domatia, a staple food of patas monkeys (Erythrocebus patas) in Laikipia, Kenya

The ants that live in the swollen thorns (domatia) of Acacia drepanolobium are staple foods for patas monkeys (Erythrocebus patas). To obtain a better understanding of these insects as resources for patas monkeys, we sampled the contents of 1,051 swollen thorns (ant domatia) over a 22-month period from December 1999 to September 2001, in Laikipia, Kenya. First, we confirmed that of the four species of ants that live on A. drepanolobium, Crematogaster sjostedti, the competitively dominant ant in this system, does not rear significant brood in the swollen thorns and is therefore not a major food item of patas monkeys. Second, across the other three species that do use swollen thorns for rearing their brood, C. nigriceps, C. mimosae, and Tetraponera penzigi, the number of worker ants per swollen thorn increased with increasing competitive dominance. Third, although there was considerable month-to-month variation in the number of workers, immatures, and especially alates (winged reproductives) within species, there was less variation across species because ant production was asynchronous. Variation in domatia contents was poorly related to rainfall for each of the three species. Finally, distal thorns held more alates and fewer workers than interior thorns, and branches higher off the ground held more alates and more workers than lower branches. For the numerically dominant C. mimosae, higher branches held significantly more immature ants than did lower branches. Ants are reliable food resources for patas monkeys, and are probably more reliable than many plant resources in this highly seasonal environment. We estimate that patas monkeys may get as much as a third of their daily caloric needs from these ants year-round. As ants and other insects are widely consumed by primates, we suggest that greater consideration be given to species differences in animal food choices and that further studies be conducted to examine the degree to which ants influence energy intake and reproduction in other primates.     

Diet for a small primate: Insectivory and gummivory in the (large) patas monkey (Erythrocebus patas pyrrhonotus)

A 17 month field study of unprovisioned patas monkeys (Erythrocebus patas pyrrhonotus) in Laikipia, Kenya, using both ad libitum and scan sampling techniques, revealed that the diet of patas monkeys consists primarily of gum of Acacia drepanolobium, arthropods (both free-living and concentrated in the swollen thorns of A. Drepanolobium), and other animals. This type of diet is normally found only in smaller-bodied primates. Results from vegetational transects suggest that the larger-bodied patas monkey can subsist on such a diet because gum and arthropods are relatively easily found in their habitat, thereby minimizing search time. Patas monkeys also spend more time moving and less time feeding (while not moving) than other Old World primates. The characteristic long limbs of patas may have evolved in response to feeding on small, nonusurpable, and widely distributed foods, in which access to foods is maximized while time and energy spent in terrestrial travel between food sites are minimized. Am. J. Primatol. 45:381–398, 1998. © 1998 Wiley-Liss, Inc.     

Long-term study of the social dynamics of patas monkeys (<Emphasis Type="Italic">Erythrocebus patas</Emphasis>): group male supplanting and changes to the multi-male situation

Data on social changes in patas monkey (Erythrocebus patas) groups were collected to clarify the general characteristics of male supplantation and to evaluate the overall role of supplanting in patas society. Seven patas groups were observed in Kala Maloue National Park, Northern Cameroon for 11 years. Analysis of this data revealed that social change, such as male supplanting, was restricted to the mating season. Male supplanting occurred in the course of outsider males seeking to gain access to estrous females within the heterosexual group and supplanting was inevitably followed by a multi-male situation arising in the group. Many cases of multi-male invasion were preceded by the supplanting of resident males and the multi-male situation arose due to a temporary absence of serious aggression towards invader males by the new resident males. Notably, an all-male group was found only once and it did not contribute to the supplanting of resident males in the one-male group. Electronic Publication     

Seasonal, sex, and interspecific differences in activity time budgets and diets of patas monkeys (Erythrocebus patas) and tantalus monkeys (Cercopithecus aethiops tantalus), living sympatrically in northern Cameroon

I examined seasonal, sex, and interspecific differences in activity time budgest and diets of patas (Erythrocebus patas) and sympatric tantalus monkeys (Cercopithecus aethiops tantalus) on the basis of 5-day data sets collected in three and two different seasons, respectively, by the method of focal animal sampling. The seasons included species-specific mating and birth seasons. As compared with not only the birth season but also conspecific females, both patas resident male and tantalus male spent less time feeding and more time resting, day and night, in their respective mating seasons. Given that day-resting time includes time for vigilance for non-resident males and receptive females, this may reflect that males should minimize time spent feeding to allow maximum participation in other fitness-increasing activities such as mating-relating activities asSchoener (1971) predicted. In both species, the males consumed fruits containing less protein but more calories and showed a high feeding rate to compensate for the shorter time spent feeding in the mating season. In contrast, females consumed protein-rich food types (i.e. animals, protein-rich seeds, leaves, and flowers) in the birth season to meet the high demand for protein due to pregnancy and lactation. Given that the season for males was considered to be not a calendar but a reproductive “season” (i.e. mating or birth season), both sexes of patas spent more time moving and less time day- and night-resting than did the tantalus counterparts irrespective of the “season”. Patas subsisted on fruits, gums, and supplementarily lipid-rich seeds as an energy source and animal matters and protein-rich seeds as a protein source. In contrast, tantalus subsisted on fruits and lipid-rich seeds as energy and flowers and leaves as protein.     

Locomotor activity differences between sympatric patas monkeys (Erythrocebus patas) and vervet monkeys (Cercopithecus aethiops): Implications for the evolution of long hindlimb length in Homo

Homo erectus is notable for its taller stature and longer lower limbs relative to earlier hominids, but the selective pressures favoring such long limbs are unclear. Among anthropoid primates, patas monkeys (Erythrocebus patas) and extant hominids share several extreme characteristics involved with foraging and movement, including the relatively longest lower limb proportions, longest daily travel distances and largest home ranges for their body or group size, occupancy of some of the driest habitats, and very efficient thermoregulatory systems. We suggest that patas monkeys are an appropriate behavioral model with which to speculate on the selective pressures that might have operated on H. erectus to increase lower limb length. Here, in a comparison of the locomotor activities of patas monkeys and sympatric, closely related vervet monkeys (Cercopithecus aethiops), we provide evidence for the hypothesis that patas use their long stride more to increase foraging efficiency while walking than to run, either from predators or otherwise. Am J Phys Anthropol 105:199–207, 1998. © 1998 Wiley-Liss, Inc.     

Reduction of passive extension and radiographic evidence of degenerative knee joint diseases in cage-raised and free-ranging aged rhesus monkeys (Macaca mulatta)

The knee joints of aged (greater than or equal to 15 years) rhesus macaques raised and maintained in individual cages were compared with those of formerly free-ranging monkeys using radiographs and measures of passive joint flexion and extension. Free-ranging monkeys had a significantly higher prevalence (p less than 0.01) and severity (p less than 0.0003) of degenerative joint diseases (osteoarthritis and/or pseudogout) based on radiographic findings and significantly (p less than 0.02) more restricted passive knee joint extension than caged animals of the same age.     

Dominance relationships among one-male units in a provisioned free-ranging band of the Sichuan snub-nosed monkeys (Rhinopithecus roxellana) in the Qinling Mountains, China

We studied the dominance relationships among one-male units (OMUs) in a provisioned free-ranging band of the Sichuan snub-nosed monkeys (Rhinopithecus roxellana) in the Qinling Mountains of central China from 2001 to 2005. The band was composed of 6-8 OMUs that stayed in the band for several years. Linear dominance orders could be detected using displacement interactions with directional asymmetry among OMUs in 82.3+/-5% of interactions, and ambiguous and reversed interactions in 17.7+/-5%. The dominance rank of OMUs was positively related with the duration of their stay in the band, and this may be attributed to the association of the resident male with adult females, rather than the fighting ability of resident males, as males do not fight seriously with each other. Subordinate units were observed to merge with dominant units resulting in an elevation of their rank order. The linear dominance relationship among OMUs in the Sichuan snub-nosed monkeys may have evolved as a result of competition for preferred food trees.     

Object manipulation in a captive troop of Japanese monkeys (Macaca fuscata): A developmental analysis

A captive troop of Japanese monkeys (Macaca fuscata) was presented with a nylon rope, a wooden cube, and an iron tube, and their subsequent manipulations were observed in detail. In total, 202 manipulation patterns were distinguished on the basis of three components: the actions performed, body-parts used, and relations to other objects. The developmental changes in these modes of manipulation were analyzed cross-sectionally, revealing four characteristics: (1) the most manipulative members of the troop were those aged 2–3 and 4–6 years old; (2) most of the manipulatory repertoire appeared by 4–6 years old; (3) actions such as Roll, Rub, and Slide and the use of bodyparts continued to increase in variety until 4–6 years old, while the variety of other actions showed plateaus after 2–3 years old or an earlier age; and (4) secondary manipulations appeared at 1 year old and continued to increase in variety even after 4–6 years old.