Search

Anthropogenic tropical deforestation and degradation imminently threaten primates today. Primates living in these disturbed habitats may also be subjected to increasingly severe tropical storms such as cyclones or hurricanes. These disturbances pose an immediate risk to their livelihood and can dramatically alter their habitats, in turn potentially shifting behavioral patterns. We had the unique opportunity to study the effects of seasonality, anthropogenic disturbances, and the immediate effects of a cyclone on the behavior of the critically endangered northern sportive lemur (NSL) in an anthropogenically disturbed forest in Madagascar. Cyclone Enawo made landfall on March 7, 2017 in northeast Madagascar with sustained wind speeds of 230 km/h. We collected behavioral data on nine individual NSLs during both wet and dry seasons, before and after Cyclone Enawo, and in areas of differing human activity, using scan sampling at 5‐min intervals. We ran generalized linear mixed models to test the effects of seasonality and disturbances on behavior. We found that NSLs spent more time feeding in dry months compared with wet (Z = −4.21, p < 0.001). More specifically, they spent more time‐consuming leaves and vine species in the dry season (Z = −2.26, p = 0.02; Z = −2.3; p = 0.02). We also found that NSLs were observed at lower heights in trees after the cyclone (Z = −2.45; p = 0.016) and spent more time in the interior portions of trees (Z = 3.44; p < 0.001), perhaps due to extensive limb damage of emergent trees documented after the cyclone. Our analyses show that seasonality affected most aspects of NSL behavior, followed by the effects of Cyclone Enawo, with anthropogenic disturbances having little effect. Our data suggest that the behavioral flexibility of NSLs in response to predictable seasonality may enable them to respond similarly to stochastic climatic disturbances. However, their generalist diet may allow them to persist in anthropogenically disturbed landscapes without the need to greatly alter their behavior. Highlights: Seasonality impacts most aspects of northern sportive lemur behavior while little variation in behavior was observed in response to anthropogenic disturbances.Immediately after Cyclone Enawo, northern sportive lemurs were observed at lower heights in trees and spent significantly more time at the interior portions of trees than before the cyclone.The biggest threat to northern sportive lemurs may not be their ability to persist in altered and degraded landscapes, but the limited availability of possible habitat at Montagne des Français and the increasing fragmentation of what few patches still remain. [ABSTRACT FROM AUTHOR]

In remembrance of Charles T. Snowdon (Chuck), 1941–2023, world renown Primatologist and member of ASP. [ABSTRACT FROM AUTHOR]

Interest in intraspecific behavioral variation has grown with concerns about the ability of primates to adapt to the rapidly changing ecological and demographic conditions that threaten their survival. Now, in addition to identifying the causes and phylogenetic distribution of normative, species-specific behavior patterns for interspecific comparisons, there is widespread recognition of the need to incorporate intraspecific variation. This variation is evident across groups and populations of the same species as well over the long histories of single groups of long-lived, socially complex animals with overlapping generations. Yet, analyses of both cross-sectional and longitudinal data require explicit criteria about how to classify and interpret behavioral variation, and must be sensitive to the limitations of space-for-time substitutions in these comparisons. Current approaches have made great advances, but there remains an urgent challenge of understanding intraspecific variation in a way that will facilitate the development of new predictive models to assess population resilience and extinction risks in the face of climate change and other anthropogenic influences. [ABSTRACT FROM AUTHOR]

An introduction is presented in which the editor discusses various reports within the issue on topics including the role of American Anthropological Association (AAA) and American Association for the Advancement of Science (AAAS), and membership in Biological Anthropology Section (BAS).

The article presents a discussion on why anthropology needs primatology, adapted from the Distinguished Lecture for the General Anthropology Division delivered at the American Anthropological Association annual meeting on November 80, 2010 in New Orleans, Louisiana.

Long-term field studies of wild primates can have far-reaching impacts that transcend their contributions to science. These impacts can benefit not only the study animals, study areas, and local human communities, but they can also have unintended, potentially negative consequences. Examples of some of the positive impacts from the Northern Muriqui Project of Caratinga, in Minas Gerais, Brazil, include contributions to conservation efforts on behalf of this critically endangered species, capacity building through the training of Brazilian students, and employment opportunities for local people through our collaboration with a locally administered NGO that is facilitating ecotourism, education, and reforestation programs. Some concerns about unintended consequences of the research include the effects of our trails and trail traffic on surrounding vegetation and other aspects of the environmental “footprints” that both long-term researchers and short-term visitors may leave. In addition, although precautions against potential health risks from routine exposure to human observers are now standard protocol, little is known about the other ways in which our long-term research presence can affect the primates' experiences or alter their perceptions of their social and ecological environments. Risk analysis, which weighs both the positive and negative impacts can provide useful perspectives for addressing the ethical considerations that can arise during long-term field studies. Am. J. Primatol. 72:772–778, 2010. © 2010 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

The 957-ha forest at the Estação Biológica de Caratinga/Reserva Particular do Patrimônio Natural-Felìciano Miguel Abdala, in Minas Gerais, Brazil, supports one of the largest known populations of the critically endangered northern muriqui (Brachyteles hypoxanthus). We combine long-term data on one group that has been monitored since 1982 with new data obtained on the other three groups since 2002 and 2003 to describe the demographic structure of this population, evaluate its potential for future growth, and predict how dispersal and competitive regimes may change in response to current demographic conditions. As of January 2005, the 226 individuals in the population were divided into four mixed-sex groups with 37-77 members, and an all-male unit whose eight males maintained transient associations with two of the mixed-sex groups. Although 51.77% of the population was female, the sex ratio among adults and subadults was female-biased (0.75), while that among immatures was male-biased (1.47). Consistent with expectations from mean interbirth intervals, 64.18% of adult females gave birth in 2003 and 2004. However, by January 2005, only 52.31% of adult females were still carrying infants < 24 months of age due to unusually high infant mortality. First-year survivorship among the 25 infants born in the population in 2003 was only 76%, considerably lower than previously documented in the longest-studied group. High female fecundity is indicative of a healthy population, but the current male bias in births will result in a decline in the population growth rate within two decades, and may increase levels of male reproductive competition and alter dispersal patterns. [ABSTRACT FROM AUTHOR]

The papers in this issue were inspired by a symposium we organized for the 27th Annual Meeting of the American Society of Primatologists, held in June 2004. The purpose of the symposium was to highlight some of the new ways in which noninvasive techniques for measuring steroids are being employed to investigate the relationships between hormones and behavior in wild primates. Endocrinological data from the field provide new insights and more precise interpretations of behavioral data on topics ranging from social and reproductive strategies to seasonality, reproductive suppression, concealed ovulation, and development. Advances in the development of methods for extracting steroids from urine and feces have increased the options available to field workers, who can now select the most appropriate methodology for their study subjects, field conditions, and specific research questions. Field-based studies of behavioral endocrinology have spread to include a wide diversity of primate species. As the scope of these studies continues to grow, we anticipate the emergence of a dynamic new field in which comparative models of primate behavioral endocrinology contribute new perspectives on primates. Am. J. Primatol. 67:1–4, 2005. © 2005 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

We measured fecal androgen (T+DHT) and estradiol (E2) levels in female northern muriquis (Brachyteles hypoxanthus) at the Estação Biológica de Caratinga/RPPN Feliciano Miguel Abdala, Minas Gerais, Brazil, to evaluate the hormonal bases underlying individual variation in the resumption of cycling and conception. We found that androgen levels were significantly lower in females than in males, and that there were no consistent patterns in female androgen levels across precycling or cycling conditions. Females that resumed cycling earlier in the study (weeks 4–8) had higher precycling E2 levels and correspondingly lower precycling androgen/E2 ratios than females that resumed cycling later (weeks 12–16). There were no differences in female precycling androgen levels, but cycling females that conceived during or immediately after the study period had lower androgen levels and threefold higher E2 peaks than the one cycling female that failed to conceive. These results suggest that minimum E2 thresholds are necessary for both the resumption of ovarian cycling and conception. Individual variation in these components of fertility may be regulated by differences in E2 levels, which affect androgen/E2 ratios, rather than by androgen levels per se. Further research into the relative concentrations of T vs. DHT will be necessary to fully evaluate whether androgens affect cycling and conception in this species. Am. J. Primatol. 67:69–81, 2005. © 2005 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

We investigated hormonal and behavioral changes in wild male and female northern muriquis (Brachyteles arachnoides hypoxanthus ) at the Estação Biológica de Caratinga, Minas Gerais, Brazil, during a 6-mo period that encompassed the onset of the 1998–1999 mating and conception seasons. Individual females resumed mating with the resumption of ovarian cycling, which was not synchronized among them or related to their cortisol levels. Females experienced two to seven cycles prior to conceiving, and the first conception occurred 2 mo after the onset of the group's mating season. There were no differences in female cortisol levels across their premating, mating, and conception conditions. Cortisol levels were significantly higher in females than in males prior to the conception season, consistent with the prediction that energy reserves may be associated with breeding readiness in females, but not males, in this species. The sustained elevation in male cortisol occurred after the peak in their sexual activity, which resulted in the first conception of the year. Male cortisol levels were positively correlated between years that were similar in rainfall, but differed in the timing of sexual and reproductive events. The timing of cortisol elevations in males appears to be generally regulated by environmental cues, but is responsive to fine-tuning by social and behavioral cues related to the unpredictable timing of reproductive opportunities within their extended mating season. Am. J. Primatol. 61:85–99, 2003. © 2003 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Nonhuman primates occupy a special niche in anthropology because of the comparative insights into humans they provide. Initial anthropological interest in primates targeted the apes for their close phylogenetic relationships with humans, and the semiterrestrial Old World monkeys for their ecological similarities with hominids adapting to life on the ground. From the earliest anecdotal reports of tool use and hunting to more contemporary quantitative analyses of local "cultural" traditions, nonhuman primates have challenged deep-rooted concepts of human uniqueness and redefined the boundaries between us and other animals. Yet, despite the long-standing influence of primate studies in anthropology, approaches to studying primates began diverging from those of earlier ethnographers. Advances in primatology, particularly during the 1990s, have included a much deeper understanding of how ecology, phylogeny, and demography affect behavior. Insights into intraspecific, population-level variation represent an important area of convergence between primatology, other areas of anthropology, and conservation biology. [ABSTRACT FROM AUTHOR]

The growth of primate field studies has occurred along multiple dimensions representing expansion in the number of species studied, comparative studies of different populations of the same species, and populations and groups studied over time. The accumulation of data on a broader taxonomic diversity of primates has contributed to advances in the use of comparative methods for gaining insights into interspecific variation in behavior patterns, but the incorporation of intraspecific variation into comparative models of behavior has lagged behind. This delay can be attributed, in part, to the slow rate at which the interacting effects of life history and demography on behavior emerge in slow-growing, long-lived primates. It may also reflect the anthropocentric foundation of field primatology, which historically focused on interspecific comparisons with humans instead of interpopulation variation among primates. Conservation concerns have stimulated new thinking about the importance of populations and the range of behavioral variation that populations maintain. The integration of intra- and interspecific behavioral variation will distinguish the next generation of comparative models in primatology, and set a new agenda as field primatology comes of age. Yrbk Phys Anthropol 46:2-13, 2003. © 2003 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

The growth of primate field studies has occurred along multiple dimensions representing expansion in the number of species studied, comparative studies of different populations of the same species, and populations and groups studied over time. The accumulation of data on a broader taxonomic diversity of primates has contributed to advances in the use of comparative methods for gaining insights into interspecific variation in behavior patterns, but the incorporation of intraspecific variation into comparative models of behavior has lagged behind. This delay can be attributed, in part, to the slow rate at which the interacting effects of life history and demography on behavior emerge in slow-growing, longlived primates. It may also reflect the anthropocentric foundation of field primatology, which historically focused on interspecific comparisons with humans instead of interpopulation variation among primates. Conservation concerns have stimulated new thinking about the importance of populations and the range of behavioral variation that populations maintain. The integration of intra- and interspecific behavioral variation will distinguish the next generation of comparative models in primatology, and set a new agenda as field primatology comes of age. Yrbk Phys Anthropol 46:2-13, 2003. [ABSTRACT FROM AUTHOR]

We monitored the birth patterns of sympatric brown howler monkeys (Alouatta fusca clamitans ) and northern muriquis (Brachyteles arachnoides hypoxanthus ) during a 4-yr period from October 1996 to August 2000 at the Estação Biológica de Caratinga, Minas Gerais, Brazil. Brown howler monkey births (n = 34) occurred throughout the year, and birth frequencies did not differ between rainy and dry season months. The aseasonal birth patterns of the howler monkeys differed significantly from the dry season concentration and dry month peak in muriqui births (n = 23). We found no effects of infant sex or the number of females on interbirth intervals (IBIs) in our 10 howler monkey study troops. IBIs of brown howler monkeys averaged 21.2 ± 2.5 mo (n = 8, median = 21.0 mo), and were significantly shorter following dry season births than rainy season births. Their IBIs and yearling survivorship (74%) were similar to those reported for other species of howler monkeys, but yearling survivorship was much lower than that of muriquis (94%), whose IBIs were more than 12 mo longer than those of the howler monkeys. Our study extends comparative knowledge of birth patterns in Alouatta to a poorly known species, and provides insights into the different ways in which diet and life history may affect the timing of births in large-bodied platyrrhines under the same seasonal ecological conditions. Am. J. Primatol. 55:87–100, 2001. © 2001 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Focuses on the disciplines of physical anthropology. Concerns on human evolution and variation in the context of biological anthropology; Description of the comparative behavior and ecology of primates; Effects of revolutionary relatedness among species; Comparison of populations under different ecological and demographic conditions.

Black‐and‐white snub‐nosed monkeys (Rhinopithecus bieti) rely on behavioral and dietary flexibility to survive in temperate latitudes at high‐elevation habitats characterized by climate and resource seasonality. However, little is known about how elevation influences their behavioral and dietary flexibility at monthly or seasonal scales. We studied an isolated R. bieti population at Mt. Lasha in the Yunling Provincial Nature Reserve, Yunnan, China, between May 2008 and August 2016 to assess the impacts of elevation on feeding behavior and diet. Across our sample, R. bieti occupied elevations between 3031 and 3637 m above mean sea level (amsl), with a 315.1 m amsl range across months and a 247.3 m amsl range across seasons. Contrary to expectations, individuals spent less time feeding when ranging across higher elevations. Lichen consumption correlated with elevation use across months and seasons, with individuals spending more time feeding on this important resource at higher elevations. Leaf consumption only correlated with elevation use during the spring. Our results suggest that R. bieti do not maximize their food intake at higher elevations and that monthly and seasonal changes in lichen and leaf consumption largely explain variation in elevation use. These findings shed light on the responses of R. bieti to environmental change and offer insight into strategies for conserving their habitats in the face of anthropogenic disturbance. Research Highlights: Black‐and‐white snub‐nosed monkeys (Rhinopithecus bieti) spend less time feeding in months and seasons when occupying higher‐elevation habitats.Leaves only comprise a higher percentage of the R. bieti diet when occupying higher‐elevation habitats in the spring.Lichen comprise a higher percentage of the R. bieti diet in months and seasons when occupying higher‐elevation habitats. [ABSTRACT FROM AUTHOR]

Examines the myth of the typical primate within the context of research paradigms. Origin of the myth; Primate societies; Evaluation of some ecological models of primate social systems.

Fecal samples were collected systematically during a 6-week period, from 13 September-24 October, 1990, from four nonlactating female muriquis (Brachyteles arachnoides) inhabiting an 800 ha forest at Fazenda Montes Claros in Minas Gerais, Brazil. All four females were experienced mothers; one had most recently given birth in June 1988; the other three had most recently given birth in August 1988. Fecal assays measuring progesterone, estradiol, and estrone indicated consistently low levels in the one female who had given birth in June 1988 and in two of the three females who had given birth in August 1988. Elevated steroid levels did, however, appear in fecal samples from the fourth female on day 15 of the collection period. Steroid levels subsequently dropped and then began to rise again during what appeared to be a second cycle. The cycling female was the only one of the four females examined observed to copulate during the collection period. These preliminary data indicate that nonlactating female muriquis do not cycle year-round, resumption of cycling is not tightly synchronized among females even when their prior parturitions were tightly synchronized, and resumed sexual activity appears to be associated with resumed cycling. [ABSTRACT FROM AUTHOR]

Data on feeding behavior in one group of muriquis (Brachyteles arachnoides) were collected during a 14 month study at Fazenda Montes Claros, Minas Gerais, Brazil. Muriquis devoted an average of 51% of their annual feeding time to leaves, 32% to fruits, and 11% to flowers. The high proportion of leaves in their diet is consistent with predictions from the energetics of body size. However, they devoted a greater proportion of their feeding time to patchy fruit and flower resources than was expected from comparisons with smaller, sympatric howler monkeys. Muriqui diet varied with the availability of preferred food types across sample months. Fruit and flower consumption corresponded to the availability and abundance of these food resources in the forest. Leaves contributed substantially to muriqui diet throughout the year but appeared to be eaten primarily to provide necessary protein and/or necessary bulk. Male and female diets differed only in the greater proportion of feeding time females devoted to flowers. [ABSTRACT FROM AUTHOR]

One group of woolly spider monkeys, or muriquis (Brachyteles arachnoides), was observed from June 1983 through July 1984 at Fazenda Montes Claros, Minas Gerais, Brazil. The study subjects spent an average of 49% of their daylight time resting, 29% traveling, and 19% feeding. They shifted their diurnal schedule of activities in response to seasonal changes in temperature and rainfall. The activity budgets of adult males and females were similar. However, a comparison of three adult females in different reproductive conditions revealed that the lactating female spent a greater proportion of time feeding than did both the pregnant and nonreproductive females. Intraspecific differences in group size and diet appear to be important to understanding differences in the activity budgets of Brachyteles. Differences between locomotion patterns of woolly spider monkeys and sympatric howler monkeys may explain activity budget differences based on group size and diet. [ABSTRACT FROM AUTHOR]

Anthropological interest in nonhuman primates as models for human behavioral evolution has tended to focus on a relatively small number of species. This emphasis, coupled with a search for unifying principles that explain behavior, has led to a widespread perception of the semi-terrestrial cercopithecines as 'typical,' and therefore characteristic of most other primates. The prevalence of male-biased dispersal and female philopatry, the use of aggression to establish and maintain hierarchical relationships, and the occurrence of sex for exclusively reproductive purposes have been challenged repeatedly, but the cercopithecine model of primate behavior has nonetheless persisted in much of the anthropological literature. This review incorporates accumulating data on a diversity of primates to examine the myth of the typical primate. The roles of kinship, aggression, and sex in mediating primate social relationships are far less uniform across primates than the myth has implied, raising questions about the generality of models of primate social systems derived from 'typical' primates. Acknowledging existing diversity and encompassing it in more accurate portrayals of primate behavioral ecology requires consideration of the interacting effects of phylogenetic, demographic, ontogenetic, and physiological variables. © 1994 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Conservation funding is currently limited; cost‐effective conservation solutions are essential. We suggest that the thousands of field stations worldwide can play key roles at the frontline of biodiversity conservation and have high intrinsic value. We assessed field stations' conservation return on investment and explored the impact of COVID‐19. We surveyed leaders of field stations across tropical regions that host primate research; 157 field stations in 56 countries responded. Respondents reported improved habitat quality and reduced hunting rates at over 80% of field stations and lower operational costs per km2 than protected areas, yet half of those surveyed have less funding now than in 2019. Spatial analyses support field station presence as reducing deforestation. These "earth observatories" provide a high return on investment; we advocate for increased support of field station programs and for governments to support their vital conservation efforts by investing accordingly. [ABSTRACT FROM AUTHOR]

This study reports for the first time the infestation of Cebidicola armatus in Brachyteles hypoxanthus. In total, 14 lice were recovered of an individual in Minas Gerais, Brazil. These were subjected to a microscopic analysis and the identification of C. armatus was carried out through its very characteristic morphology. [ABSTRACT FROM AUTHOR]

The northern muriqui (Brachyteles hypoxanthus) is a critically endangered species endemic to the Atlantic Forest of southeastern Brazil. Long‐term observational studies of wild muriquis have provided many insights into the behavioral ecology and life history of this species. However, nearly everything that is currently known about the northern muriqui's behavioral endocrinology has come from combining our respective expertise in noninvasive field and laboratory research. Here, we reflect on the history of our collaboration, focusing on major challenges, key scientific findings, and factors that contributed to its success. Challenges included insuring the reliable collection of frequent fecal samples from a large enough number of known individuals over extended periods of time, preserving the steroids in the field and transporting them, developing and validating the fecal steroid assays, and interpreting the hormonal profiles within the behavioral and ecological contexts of the study subjects. Major findings included our thorough description of the fecal progesterone and estradiol profiles associated with muriqui ovarian cycling and gestation, the seasonal resumption of cycling, its onset during puberty of dispersing females, and the differences between fertile and infertile cycles. We also documented the relationship between fecal cortisol and testosterone in sexually active males across breeding and nonbreeding seasons, and sex differences in cortisol levels across the mating and conception seasons. We attribute the success of our collaboration to a number of factors including our mutual appreciation for one another's high standards for ethics, data quality, and data interpretation. [ABSTRACT FROM AUTHOR]

An obituary for Kenneth Alan Bennett, professor of anthropology at the University of Wisconsin-Madison in Madison, Wisconsin, is presented.

We investigated demographic changes in three primate species (Alouatta guariba, Sapajus nigritus, and Callithrix flaviceps) at the Reserva Particular do Patrimônio Natural–Feliciano Miguel Abdala, Caratinga, Minas Gerais, Brazil, following a yellow fever outbreak (YFO) by comparing their population sizes before (2015) and after the outbreak (2017–2018), and by monitoring the size, composition, and reproductive status of groups from 2017 to 2021. Comparisons of pre‐ and post‐YFO census data indicate the A. guariba population declined by 86.6%, from an estimated minimum of 522 individuals to 70 individuals. However, by October 2021, the population had grown to at least 86 individuals, with an adult sex ratio (N = 53) that was female‐biased (0.61). Eleven of the 13 groups being monitored systematically were reproductively active with high survivorship to 12 months of age. S. nigritus declined by 40%, from 377 to 226 individuals. The sex ratio of 33 adult S. nigritus is also female‐biased (0.71), and at least 8 of 15 groups being monitored are reproductively active. C. flaviceps declined by 80%, from 85 individuals to the 15–17 individuals observed from 2017 to 2021. The female‐biased adult sex ratio and presence of infants and juveniles in the A. guariba and S. nigritus groups are encouraging signs, but there is still great concern, especially for C. flaviceps. Continued monitoring of the demographics of these primates is needed as their persistence appears to still be at risk. Research highlights: This study documented an unprecedent decline in three endemic primate species following a severe yellow fever outbreak in the Brazilian Atlantic Forest.Adult female biased sex ratios and reproductive activity suggest at least two species may be recovering from the drastic demographic changes. [ABSTRACT FROM AUTHOR]

We investigated the genetic structure and kinship patterns of black howler monkeys ( Alouatta pigra) at Palenque National Park, Mexico. Fecal samples from 49 individuals residing in eight social groups were successfully genotyped for 19 polymorphic microsatellite markers known to be variable in other ateline primates. Overall, genetic diversity was low ( Ho = 0.588) with an average of 4.2 alleles per loci (range = 2-8). We found that intergroup genetic variation among adults was relatively high (mean between-group FST = 0.119), largely due to the genetic divergence of one study group from the others. Intragroup kinship patterns showed that in most social groups, either adult males, adult females, or individuals of both sexes resided with same-sexed adult kin, suggesting that some black howler males and females may not disperse from their natal group or may disperse with related individuals. Of the six sampled immigrant males, two males joined established groups by themselves, and four males formed two pairs that each took over the social group they joined after evicting the resident males. Males in both these coalitions were genetically closely related, while the two solitary immigrants were not closely related to any of the resident males present in the group they joined. Am. J. Primatol. 74:948-957, 2012. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

We investigated whether sex differences in spatial dynamics correlate with rates of staccato and neigh vocalizations in northern muriquis (Brachyteles hypoxanthus) at the Reserva Particular do Patrimônio Natural–Feliciano Miguel Abdala, Minas Gerais, Brazil. A total of 2,727 10 min focal subject samples were collected on 32 adult females and 31 adult males between April 2007 and March 2008. Compared with males, females spent a significantly lower proportion of their time in proximity to other group members and gave staccatos at significantly higher rates while feeding, resting, and traveling. Conversely, males emitted neigh vocalizations at significantly higher rates than females when feeding and resting only. Both sexes gave significantly more staccatos when feeding than when they were engaged in other activities, but their respective rates of neighs did not vary across activities. Both females and males emitted staccato vocalizations at significantly higher rates during times of the year when preferred foods were scarce, but no seasonal differences in the rates of neigh vocalizations were observed in either sex. Females and males showed a reduction in the number of neighbors following staccato vocalizations and an increase in the number of neighbors following neigh vocalizations. Our findings of sex differences in the rates of staccato and neigh vocalizations and the effects of these vocalizations on interindividual spacing are consistent with sex differences in spatial dynamics, and confirm the role of vocal communication in mediating spatial associations in this species. Am. J. Primatol. 72:122–128, 2010. © 2009 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

We present data on the spread of terrestrial activities in one group of wild northern muriqui monkeys (Brachyteles hypoxanthus). Both males and females consumed fruit, drank, rested, traveled, and socialized terrestrially, but proportionately more males spent significantly more of their time on the ground than females, and females were more likely to engage in terrestrial activities when accompanied by males than when by themselves. Terrestrial activities occurred in both open and closed habitats where arboreal substrates were available and utilized by other individuals engaged in similar activities. Ecological and demographic factors may have stimulated the muriquis’ vertical niche expansion, but increases in the frequency and diversity of terrestrial activities, the high proportion of group members that engage in terrestriality, and its diffusion along male-biased social bonds are consistent with the development of a local terrestrial tradition similar to other types of traditions described in other primates. [Key words: terrestriality, ecology, predation, tradition] [ABSTRACT FROM AUTHOR]

Earth's rapidly changing climate creates a growing need to understand how demographic processes in natural populations are affected by climate variability, particularly among organisms threatened by extinction. Long-term, large-scale, and cross-taxon studies of vital rate variation in relation to climate variability can be particularly valuable because they can reveal environmental drivers that affect multiple species over extensive regions. Few such data exist for animals with slow life histories, particularly in the tropics, where climate variation over large-scale space is asynchronous. As our closest relatives, nonhuman primates are especially valuable as a resource to understand the roles of climate variability and climate change in human evolutionary history. Here, we provide the first comprehensive investigation of vital rate variation in relation to climate variability among wild primates. We ask whether primates are sensitive to global changes that are universal (e.g., higher temperature, large-scale climate oscillations) or whether they are more sensitive to global change effects that are local (e.g., more rain in some places), which would complicate predictions of how primates in general will respond to climate change. To address these questions, we use a database of long-term life-history data for natural populations of seven primate species that have been studied for 29-52 years to investigate associations between vital rate variation, local climate variability, and global climate oscillations. Associations between vital rates and climate variability varied among species and depended on the time windows considered, highlighting the importance of temporal scale in detection of such effects. We found strong climate signals in the fertility rates of three species. However, survival, which has a greater impact on population growth, was little affected by climate variability. Thus, we found evidence for demographic buffering of life histories, but also evidence of mechanisms by which climate change could affect the fates of wild primates. [ABSTRACT FROM AUTHOR]

Although well documented in matrilocal primate species, group fission is still a poorly known phenomenon among patrilocal primates. In this paper we describe in detail a group fission event in the population of northern muriquis at the Reserva Particular do Patrimônio Natural-Feliciano Miguel Abdala in Caratinga, Minas Gerais, Brazil, using Social Network Analyses (SNA). Data on association patterns were collected during systematic observations from May 2002 to September 2005, and analyzed for dry (from May to October) and rainy seasons (from November to April). The fission process started with subgroup formation in the rainy season 2002-2003, and was completed by the dry season of 2003. By the dry season 2003, the parent group (Jaó) had fissioned to form a second mixed-sex group (Nadir) while a subgroup of males (MU) moved between the parent group and the newly established group. Before the Jaó group fission started (dry season 2002) and during its initial phases (rainy season 2002-2003), females that ultimately composed the daughter group (Nadir) were the most peripheral in the association network. In the rainy season 2002-2003, the median monthly ( N = 6) operational sex ratio (OSR) of Jaó group was 2.81. However, once Jaó females initiated the fissioning process to establish the Nadir group, the OSR was more favorable to males in the Nadir group than in the Jaó group. Our results suggest that males followed the females to escape an unfavorable OSR in their natal group. Am. J. Primatol. 76:529-538, 2014. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Increased body size in B rachyteles has been regarded as an important evolutionary adaptation that allowed a greater reliance on leaves compared to other more frugivorous Atelidae, but its association with muriqui positional behavior and substrate use is still unknown. Here, we present original data on the feeding and resting postures of the northern muriqui ( B rachyteles hypoxanthus) and evaluate predictions about the relationships between body size, postural behavior, and substrate use derived from previously published data for other atelids (e.g. A louatta, A teles, and L agothrix). The study was undertaken from August 2002 to July 2003 on a large group of well-habituated muriquis inhabiting the Reserva Particular do Patrimônio Natural - Felíciano Miguel Abdala in Minas Gerais, Brazil. Consistent with our predictions, we found that B . hypoxanthus was highly suspensory during postural feeding (60.9%) and commonly used tail-hind limb suspension/horizontal tripod (38.0%) or tail-forelimb/hind limb suspension (21.4%). However, although tail-suspensory postures permitted the muriquis to use the terminal canopy and small-sized substrates, these areas were also accessed via tail-assisted above-branch postural behaviors involving multiple substrates. Unexpectedly, tail-suspensory postures were found to be frequently associated with large substrates, tree trunks, and the understory. We suggest that B rachyteles' ability to access food resources from all areas of a feeding tree and from tree crowns at different canopy levels may account for their ability to efficiently exploit food resources in seasonal disturbed forest fragments of the Brazilian Atlantic Forest today. Am. J. Primatol. 75:74-87, 2013. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

We studied two multimale–multifemale groups of black howler monkeys (Alouatta pigra) during a 14-month study (June 2006–July 2007) in Palenque National Park, Mexico to evaluate the ways in which their sexual behavior changes across ovarian cycles. We analyzed 231 fecal samples, collected every 2.2±1.4 days from five females. For four females, estradiol and progesterone profiles revealed an average (±SE) cycle length of 18.3±1.4 days. Copulations occurred significantly more frequently during the periovulatory period (POP), defined as the estimated day of ovulation ±3 days (N=18). This was largely the result of cycling females soliciting sexual interactions during their POPs. Females directed their solicitations significantly more often toward “central” males of their group, who had close spatial associations with females at other times, compared with “noncentral” males, who did not associate closely with females. Central males rarely solicited sexual interactions, but instead monitored the females' reproductive status by sniffing their genitals, and maintained significantly closer proximity to females during their POPs, suggesting male mate guarding when conceptions are most likely to occur. Our findings indicate that the reproductive strategies of black howler central males and females coincide, highly skewing mating opportunities toward central males. Black howler females, however, occasionally choose to copulate with noncentral resident males or extra-group males during their POPs, undermining the ability of central males to monopolize all reproductive opportunities. Am. J. Primatol. 71:153–164, 2009. © 2008 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Maternal care of offspring is ubiquitous among primates, but its duration varies across species due to factors such as dispersal patterns and social dynamics, which influence opportunities for and potential benefits of maternal investment in older offspring, respectively. We examined mother-offspring associations in wild northern muriquis (Brachyteles hypoxanthus), in which males are philopatric, females typically disperse before puberty, and social relationships among and between males and females are egalitarian. Associations were systematically recorded between ten mothers, each with two–six offspring in the study group, and all group members from August 2003–May 2004 at the RPPN-Feliciano Miguel Abdala in Minas Gerais, Brazil. Infants of both sexes received similarly high percentages of their mothers' association time. Mothers without infants also maintained strong associations with their youngest juvenile sons. Mothers did not spend consistently more time associating with either juvenile or adult sons than daughters. Our finding of non-preferential associations between muriqui mothers and their older male offspring suggests that extended maternal investment in offspring may be of minimal value in their egalitarian society compared with its value for species living in hierarchical societies. Am. J. Primatol. 70:301–305, 2008. © 2007 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Female northern muriquis (Brachyteles hypoxanthus) are known to engage in frequent copulations with multiple partners, a pattern that in other primates has been attributed to various functions such as confusing paternity, reducing male aggression, or ensuring fertilization. However, in some female primates, promiscuity is restricted to times when conceptions are unlikely. We investigated whether female northern muriquis might exhibit a similarly mixed strategy by examining their mating, social, and activity patterns during their conception cycles versus other times. Systematic behavioral data were collected during an 18-month period between August 2001 and February 2003 on 13 adult females in a well-studied group at the RPPN-Feliciano Miguel Abdala, Minas Gerais, Brazil. Females mated on an average of 12.5±7.9 days during the study period, and spent significantly less time resting and engaging in non-sexual social behaviors, and significantly more time in sexual behaviors on days that they copulated than on days they did not. Three of the eight females for which sufficient data were available copulated significantly more often with their spatially closest non-kin associates, and four of five females that could be analyzed copulated significantly more often with their most frequent non-kin embrace partners. Comparisons between conception and non-conception periods revealed no differences in female activity budgets or in either the number of copulations or the number of different mating partners per female. Our results suggest that some females mate preferentially with close associates and social partners, but there is no indication that females alter their behavior during the cycles in which they conceive. Am. J. Primatol. 69:766–776, 2007. © 2007 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Many arboreal primates descend to the ground, a custom that may occur more frequently in disturbed habitats, and in the presence of researchers to whom the primates are habituated. In this paper, we describe opportunistic observations of ground use in two groups of northern muriquis (Brachyteles hypoxanthus) at the RPPN Feliciano Miguel Abdala, Minas Gerais, Brazil. Members of both groups were observed drinking, resting, feeding, playing, and traveling on the ground to different degrees, and variation in the levels of habituation of the two groups may be responsible for the differences in the distribution of their terrestrial activities. The potential increase in vulnerability to predation or disease owing to ground use has implications for the conservation of this critically endangered species. Am. J. Primatol. 69:706–712, 2007. © 2007 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Urine, feces, and copulation frequency were collected from two captive muriqui females, Brachyteles arachnoides , at the Centro de Primatologia do Rio de Janeiro following the resumption of postpartum ovarian cycles. Fecal steroid profiles from seven wild muriqui females at the Estação Biologica de Caratinga, Minas Gerais, Brazil, were compared to the captive females to determine the approximate patterns of steroid excretion relative to the urinary LH peak. Hormonal profiles from one of the captive female muriquis revealed a discrete urinary LH peak. For this female, fecal progesterone increased on the same day as the urinary LH peak, while fecal estradiol increased 6 days later and urinary steroids increased 5 days later. For both captive females, the onset of fecal progesterone increase was preceded by the onset of copulations, which occurred during at least a 5-day period. The complete fecal hormonal profiles of the one captive female for which continuous data were available were similar to those found in wild muriqui monkeys, with the onset of an increase in sustained progesterone levels occurring several days prior to the onset of sustained estradiol increase. These patterns suggest that fecal progesterone may be excreted rapidly in this species. The onset of sustained increase in fecal progesterone levels, together with the consistent delay in the onset of the sustained increase in estradiol, may provide the best indicators of the periovulatory period for muriqui females. Am. J. Primatol. 42:311–321, 1997. © 1997 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

The taxonomy of muriquis, the largest extant primates in the New World, is controversial. While some specialists argue for a monotypic genus (Brachyteles arachnoides), others favor a two‐species classification, splitting northern muriquis (Brachyteles hypoxanthus) from southern muriquis (B. arachnoides). This uncertainty affects how we study the differences between these highly endangered and charismatic primates, as well as the design of more effective conservation programs. To address this issue, between 2003 and 2017 we collected over 230 muriqui fecal samples across the genus' distribution in the Brazilian Atlantic Forest, extracted DNA from these samples, and sequenced 423 base pairs of the mitochondrial DNA (mtDNA) control region. Phylogenetic and species delimitation analyses of our sequence dataset robustly support two reciprocally monophyletic groups corresponding to northern and southern muriquis separated by an average 12.7% genetic distance. The phylogeographic break between these lineages seems to be associated with the Paraíba do Sul River and coincides with the transition between the north and south Atlantic Forest biogeographic zones. Published divergence estimates from whole mitochondrial genomes and nuclear loci date the split between northern and southern muriquis to the Early Pleistocene (ca. 2.0 mya), and our new mtDNA dataset places the coalescence time for each of these two clades near the last interglacial (ca. 120–80 kya). Our results, together with both phenotypic and ecological differences, support recognizing northern and southern muriquis as sister species that should be managed as distinct evolutionarily significant units. Given that only a few thousand muriquis remain in nature, it is imperative that conservation strategies are tailored to protect both species from extinction. Research Highlights: Phylogenetic analysis of mitochondrial DNA from "northern" and "southern" muriquis identifies these primates as falling into two reciprocally monophyletic lineages. These taxa also differ phenotypically, ecologically, and possibly behaviorally.While dated mitochondrial and nuclear DNA phylogenies suggested the divergence between the two Brachyteles species around the start of the Pleistocene (ca. 2.0 mya), the coalescence times for both the northern and southern lineages are much more recent (ca. 120–80 kya).Together, these data support the recognition and conservation management of northern and southern muriquis as distinct species. [ABSTRACT FROM AUTHOR]