Primatology

The Effect of Dominance Rank on the Distribution of Different Types of Male–Infant–Male Interactions in Barbary Macaques ( Macaca sylvanus ) Abstract In several cercopithecine species males exhibit a specific type of male–infant–male interaction during which two males briefly manipulate an infant. These interactions typically occur after a male carrying an infant (infant holder) approaches or is approached by another male who is not holding an infant (infant nonholder). The agonistic buffering and relationship management hypotheses explain these interactions as a tool to establish and maintain social bonds among males. Both hypotheses predict that males preferentially use the opportunity to interact and bond with males dominant to themselves. However, the agonistic buffering hypothesis predicts that males preferentially initiate male–infant–male interactions with the highest ranking males available, whereas the relationships management hypothesis predicts that males are more likely to interact with males that are close to them in rank. To test these predictions, we collected data on 1562 male–infant–male interactions during 1430 hours of focal observation of 12 infants in one group of wild Barbary macaques (Macaca sylvanus) in Morocco. Using generalized linear mixed-effect models we found that males preferably initiated interactions with males that were dominant to them. However, we observed this effect only for interactions initiated by the infant holder. In interactions initiated by non-holders, the receiver's relative rank did not predict the frequency of interactions. Males also initiated more interactions with males close in rank to themselves than distantly ranked males. Our results support the relationship management hypothesis, but also indicate that the different types of male–infant–male interactions may require different explanations.

Interpreting People's Behavior Toward Primates Using Qualitative Data: a Case Study from North Morocco Abstract People's perceptions of primates vary across and within cultures and may not be consistent with their behavior toward the primates themselves. We used qualitative data from semistructured and unstructured interviews with shepherds from 10 villages around Bouhachem oak forest in Morocco to describe and discuss shepherds' behavior when they encounter Barbary macaques (Macaca sylvanus). When macaques enter agricultural fields to feed on crops, mature men trap, attach a marker to them (a hat or a rattle), and release them. In contrast, young men and boys working as shepherds hunt and kill macaques when they encounter them in the forest. We interpret these findings in the context of the historical, social, and cultural factors that underlie these cross-species encounters. We suggest the different ways men behave toward macaques over their lives are related to their age and social status. Understanding that men's behavior varies, and changes over the life course, we continued to engage positively with shepherds of all ages, sharing general information about the macaques and conducting community projects benefiting villagers' health. This strategy led shepherds from six villages to stop hunting macaques, with the behavior of young men and boys changing to reflect that of older men. We suggest that gaining a deep, contextualized understanding of the human–primate interface and fostering intrinsic values for a species are effective in gaining communities' support and fundamental to facilitating changes in people's behavior in favor of conservation.

The Contributions to Primatology of Colin P. Groves (1942–2017): Corecipient of the Lifetime Achievement Award of the International Primatological Society, 2018

Correction to: Camera Traps Clarify the Distribution Boundary between the Crested Black Macaque ( Macaca nigra ) and Gorontalo Macaque ( Macaca nigrescens ) in North Sulawesi The original version of this article unfortunately contained a mistake in Figure 1. The revised figure is presented below:

Dorothy Cheney (1950–2018)

Camera Traps Clarify the Distribution Boundary between the Crested Black Macaque ( Macaca nigra ) and Gorontalo Macaque ( Macaca nigrescens ) in North Sulawesi Abstract Primates are among the most threatened taxa of mammals in the world. Tracking the status of primates requires continually assessing population distribution, abundance, and threats, which in turn requires the extent of a species' occurrence to be known. Defining this important parameter in practice can be difficult. In this article we demonstrate how camera traps can be used to address this with a case study involving two macaque species on the northernmost peninsula of Sulawesi, Indonesia. We deployed 83 camera traps across the suspected interface between the Critically Endangered Macaca nigra and the Vulnerable Macaca nigrescens. Using spatially explicit photographic records of both species, we found the boundary between the two species is 14.85 km farther west than previously defined. We estimate that the additional area encompassed by this new boundary location equates to 224 km2 of suitable habitat for M. nigra, an increase of 7.5%. This has important implications for more accurately assessing the threatened status of both species in the future. As camera traps become cheaper, their deployment at broader spatial scales is becoming more feasible, which in turn provides opportunities to enhance our ecological understanding of species. Here, we demonstrate an additional insight that can be gained from such technology, by showing how the range extent of a Critically Endangered primate can be accurately demarcated. Accordingly, we encourage primatologists to think more broadly about the possible applications of camera traps and to include them as tools in their conservation inventories.

Phylogeography, Population Genetics, and Conservation of Javan Gibbons ( Hylobates moloch )

Craniofacial Shape and Nonmetric Trait Variation in Hybrids of the Japanese Macaque ( Macaca fuscata ) and the Taiwanese Macaque ( Macaca cyclopis ) Abstract It has become apparent that natural hybridization is far more common and may play a much greater role in evolution than has historically been recognized. The skeletal morphology of hybrid primates is notoriously variable and difficult to predict. Indeed, before the advent of genetic sequencing techniques, many wild hybrid populations went undetected. Though many species of primates are now known to hybridize naturally and are likely to have done so for millions of years, anthropogenic alterations to the environment are increasingly restricting or altering primate species ranges and contact zones and driving hybridization between populations that may otherwise never have come into contact. The case of hybridizing Japanese and Taiwanese macaques (Macaca fuscata and Macaca cyclopis) is an excellent example of this, as these two island species could not have come into contact without human interference. Here we apply 3D geometric morphometrics and nonmetric trait analysis to the crania and dentition of hybrid macaques (N = 70) and their parental species, M. fuscata (N = 57) and M. cyclopis (N = 51). The exploration of 3D shape variation identifies mildly transgressive morphology in the hybrids and a general tendency toward the M. fuscata morphotype overall, but less variability in the hybrid morphotype than has been identified in previous studies of primate hybrids. We also identify a small number of nonmetric traits that differentiate the hybrids from the parental species, although the power of these traits to distinguish between groups is weak and their relationship with hybridity is unclear. We conclude that the relatively short divergence time between the parent species is likely to help explain the observed differences in hybrid morphotype, and that further exploration of the relationship between degree of evolutionary divergence and hybrid morphology may help us to better explain and predict hybrid morphology in other taxa.

An Application of Autonomous Recorders for Gibbon Monitoring Abstract Population monitoring is very important in wildlife management and conservation. All 18 species of gibbons are considered threatened with extinction and listed on the IUCN Red List of Threatened Species. Thus, understanding and effectively monitoring their population trends and distribution are critical. Thus far, all gibbon surveying and monitoring programs have been conducted by human surveyors; this is expensive, laborious, and dependent on the surveyors' skills. In particular, estimating group density often requires a large sample size with several skilled observers working simultaneously in the field. We used autonomous recorders to record the calls of southern yellow-cheeked crested gibbon (Nomascus gabbrielae) for at least 3 days at each of 57 posts in Nam Cat Tien sector, Cat Tien National Park, Vietnam from July to October, 2016. We extracted gibbon calls from the recordings auditorily or visually using spectrograms in RAVEN software. We detected gibbon calls at 40 recording posts during the survey. The proportion of recorders with gibbon calls in the eastern region of Nam Cat Tien sector (mean = 0.79; SE = 0.13) was higher than that in the western region (mean = 0.46; SE = 0.11). The estimated probability of occurrence in the eastern region (ψ = 0.56; SE = 0.20) was higher than that in the western region (ψ = 0.23; SE = 0.16). Passive acoustic data were useful to investigate spatial variation in the probability of occurrence of gibbon. We recommend using autonomous recorders combined with occupancy model to complement human surveyors in gibbon monitoring in areas with low gibbon density because it is efficient, low cost, and not subject to errors caused by human surveyors. In the areas of high gibbon density, absolute density estimate achieved by human surveyors might be a more suitable indicator.

Is There a Link Between Matriline Dominance Rank and Linear Enamel Hypoplasia? An Assessment of Defect Prevalence and Count in Cayo Santiago Rhesus Macaques ( Macaca mulatta ) Abstract Linear enamel hypoplasias are developmental defects ranging in appearance from microscopic to macroscopic furrows in enamel that encircle the tooth crown. Environmental stressors, including lack of food and infectious diseases during early periods of development, are known to induce hypoplasias in human and nonhuman primates. Social correlates of hypoplasias have not been extensively studied, however. Here, we examined the relationship between matriline dominance rank and linear enamel hypoplasia prevalence (i.e., absence or presence) and count (the total number of hypoplasias observed) in free-ranging rhesus monkeys (Macacca mulatta) in Cayo Santiago, Puerto Rico. We sampled 86 female offspring from low-, mid-, and high-ranking matrilines. Our results show that although hypoplasia prevalence and count were numerically higher in the combined group of low-and mid-ranking matrilines than in high-ranking matrilines, this effect was not statistically significant. There was, however, a significant negative relationship between age and hypoplasia prevalence, as well as between age and mean number of enamel defects, likely due to the attrition and abrasion of enamel that wear away shallow defects as individuals age. Future studies would benefit from using large sample sizes and collecting detailed behavioral data to determine if and when social status mediates enamel defect formation.