A simple assay for measuring tannin-protein precipitation capacity offers insights into the diet and food choice of black howler monkeys (Alouatta pigra).

Phenolics, like tannins, are plant-specialized metabolites that play a protective role against herbivory. Tannins can reduce palatability and bind with proteins to reduce digestibility, acting as deterrents to feeding and impacting nutrient extraction by herbivores. Some assays measure tannin and total phenolics content in plants but lack determination of their biological effects, hindering the interpretation of tannin function in herbivory and its impacts on animal behavior and ecology. In this study, we successfully applied the radial diffusion assay to assess tannin protein precipitation (PP) capacity and evaluate the anti-nutritional effects of tannins in food plants (n = 24) consumed by free-ranging black howler monkeys (Alouatta pigra) in Tabasco, Mexico. We found PP rings in five plant species consumed by the monkeys. The mature fruit of Inga edulis was the most consumed food plant, despite having a high tannin PP capacity (56.66 mg tannic acid equivalent/g dry matter). These findings highlight the presence of tannins in the black howler diet and provide insight into the primates' resilience and potential strategies for coping with anti-nutritional aspects of the diet.

Scientific activism to protect the world's primates and their environments from extinction: Introduction to the special issue.

Nonhuman primates and their habitats are facing an impending extinction crisis. Approximately 69% of primate species are listed by the International Union for Conservation of Nature as threatened and 93% have declining populations. Human population growth (expected to reach 10.9 billion by the year 2100), the unsustainable demands of a small number of consumer nations for forest-risk commodities, deforestation and habitat conversion, the expansion of roads and rail networks, cattle ranching, the hunting and trapping of wild primate populations, and the potential spread of infectious diseases are among the primary drivers of primate population decline. Climate change will only exacerbate the current situation. The time to act to protect primate populations is now! In this special issue of the American Journal of Primatology, we present a series of commentaries, formulated as "Action Letters." These are designed to educate and inform primatologists, conservation biologists, wildlife ecologists, political leaders, and global citizens about the conservation challenges faced by particular primate taxa and particular world regions, and present examples of specific actions that one can take, individually and collectively, to promote the persistence of wild primate populations and environmental justice for local human populations and impacted ecological communities. As scientists, researchers, and educators, primatologists are in a unique position to lead local, national, and international efforts to protect biodiversity. In this special issue, we focus on primates of the Brazilian Amazon, lemurs of northeast Madagascar, Temminck's red colobus monkey (Piliocolobus badius temminckii), night monkeys (Aotus spp.), long-tailed macaques (Macaca fascicularis), the primate pet trade, and professional capacity building to foster conservation awareness and action. We encourage primatologists, regardless of their research focus, to engage in both advocacy and activism to protect wild primate populations worldwide.

Small apes adjust rhythms to facilitate song coordination.

Song coordination is a universal characteristic of human music. Many animals also produce well-coordinated duets or choruses that resemble human music. However, the mechanism and evolution of song coordination have only recently been studied in animals. Here, we studied the mechanism of song coordination in three closely related species of wild Nomascus gibbons that live in polygynous groups. In each species, song bouts were dominated by male solo sequences (referred to hereafter as male sequence), and females contributed stereotyped great calls to coordinate with males. Considering the function of rhythm in facilitating song coordination in human music and animal vocalizations, we predicted that adult males adjust their song rhythm to facilitate song coordination with females. In support of this prediction, we found that adult males produced significantly more isochronous rhythms with a faster tempo in male sequences that were followed by successful female great calls (a complete sequence with "introductory" and "wa" notes). The difference in isochrony and tempos between successful great call sequences and male sequences was smaller in N. concolor compared with the other two species, which may make it difficult for females to predict a male's precise temporal pattern. Consequently, adult females of N. concolor produced more failed great call (an incomplete sequence with only introductory notes) sequences. We propose that the high degree of rhythm change functions as an unambiguous signal that can be easily perceived by receivers. In this regard, gibbon vocalizations offer an instructive model to understand the origins and evolution of human music.

Human activity and climate change accelerate the extinction risk to non-human primates in China.

Human activity and climate change affect biodiversity and cause species range shifts, contractions, and expansions. Globally, human activities and climate change have emerged as persistent threats to biodiversity, leading to approximately 68% of the ~522 primate species being threatened with extinction. Here, we used habitat suitability models and integrated data on human population density, gross domestic product (GDP), road construction, the normalized difference vegetation index (NDVI), the location of protected areas (PAs), and climate change to predict potential changes in the distributional range and richness of 26 China's primate species. Our results indicate that both PAs and NDVI have a positive impact on primate distributions. With increasing anthropogenic pressure, species' ranges were restricted to areas of high vegetation cover and in PAs surrounded by buffer zones of 2.7-4.5 km and a core area of PAs at least 0.1-0.5 km from the closest edge of the PA. Areas with a GDP below the Chinese national average of 100,000 yuan were found to be ecologically vulnerable, and this had a negative impact on primate distributions. Changes in temperature and precipitation were also significant contributors to a reduction in the range of primate species. Under the expected influence of climate change over the next 30-50 years, we found that highly suitable habitat for primates will continue to decrease and species will be restricted to smaller and more peripheral parts of their current range. Areas of high primate diversity are expected to lose from 3 to 7 species. We recommend that immediate action be taken, including expanding China's National Park Program, the Ecological Conservation Redline Program, and the Natural Forest Protection Program, along with a stronger national policy promoting alternative/sustainable livelihoods for people in the local communities adjacent to primate ranges, to offset the detrimental effects of anthropogenic activities and climate change on primate survivorship.

An urgent call-to-action to protect the nonhuman primates and Indigenous Peoples of the Brazilian Amazon.

Primates are facing an impending extinction crisis. Here, we examine the set of conservation challenges faced by the 100 primate species that inhabit the Brazilian Amazon, the largest remaining area of primary tropical rainforest in the world. The vast majority (86%) of Brazil's Amazonian primate species have declining populations. Primate population decline in Amazonia has been driven principally by deforestation related to the production of forest-risk commodities including soy and cattle ranching, the illegal logging and setting of fires, dam building, road and rail construction, hunting, mining, and the confiscation and conversion of Indigenous Peoples' traditional lands. In a spatial analysis of the Brazilian Amazon, we found that 75% of Indigenous Peoples' lands (IPLs) remained forested compared with 64% of Conservation Units (CUs) and 56% of other lands (OLs). In addition, primate species richness was significantly higher on IPLs than on CUs and OLs. Thus, safeguarding Indigenous Peoples' land rights, systems of knowledge, and human rights is one of the most effective ways to protect Amazonian primates and the conservation value of the ecosystems they inhabit. Intense public and political pressure is required and a global call-to-action is needed to encourage all Amazonian countries, especially Brazil, as well as citizens of consumer nations, to actively commit to changing business as usual, living more sustainably, and doing all they can to protect the Amazon. We end with a set of actions one can take to promote primate conservation in the Brazilian Amazon.

A conceptual framework for assessing behavioral flexibility of species in response to extreme climatic events.

Inherent differences in the adaptive capacity of species to flexibly respond to extreme climatic events (ECEs) represent a key factor in their survivorship. We introduce and apply a conceptual framework linking knowledge about species' current ecology and biology with variation in behavioral flexibility to ECEs. We applied it to 199 non-human primate species currently exposed to cyclones across the global tropics. Our findings suggest that species characterized by an increased ability to exploit a broad range of food types, social systems that permit subgrouping, and habitat types that span a range of environmental conditions may have greater success in coping with cyclones than more narrowly constrained or less adaptable primates. Overall, 15% of species, predominantly of the families Atelidae and Cercopithecidae, were assessed as having high or very high flexibility. In contrast, ~ 60% of primates were assessed with low or very low flexibility. These were species mainly belonging to the Cheirogaleidae, Lemuridae, Lepilemuridae, and Indriidae. While much work remains to better understand mechanisms driving differences in behavioral flexibility of species exposed to extreme climate across vertebrate lineages, our framework provides a workable approach that can improve estimates of current vulnerability to these phenomena and better inform conservation and management strategies.

Effects of provisioning on the activity budget and foraging strategies of black-and-white snub-nosed monkeys (Rhinopithecus bieti) in the Baima Snow Mountain Nature Reserve, Yunnan, China.

Provisioning can significantly affect the ranging patterns, foraging strategies, and time budget of wild primates. In this study, we document for the first time, the effects of provisioning on the activity budget and foraging effort in an Asian colobine. Over 3-years, we used an instantaneous scanning method at 10-min intervals to collect data on the activity budget of a semiprovisioned breeding band (SPB) of black-and-white snub-nosed monkeys (Rhinopithecus bieti) (42-70 individuals) at Xiangguqing (Tacheng), Yunnan, China. We then compared the effects of provisioning in our study band with published data on a sympatric wild nonprovisioned breeding band (NPB) of R. bieti (ca. 360 monkeys) at the same field site. The SPB spent 25.6% of their daytime feeding, 17.1% traveling, 46.9% resting, and 10.3% socializing. In comparison, the NPB devoted more time to feeding (34.9%) and socializing (14.1%), less time to resting (31.3%), and was characterized by a greater foraging effort (1.74 versus 0.96, foraging effort = (feeding + traveling)/resting; see Methods). There was no difference between bands in the proportion of their activity budget devoted to traveling (15.7% vs. 17.1%). In addition, the SPB exhibited a more consistent activity budget and foraging effort across all seasons of the year compared to the NPB. These findings suggest that the distribution, availability, and productivity of naturally occurring feeding sites is a major determinant of the behavioral strategies and activity budget of R. bieti. Finally, a comparison of our results with data on six nonprovisioned R. bieti bands indicates that caution must be raised in meta-analyses or intraspecific comparisons of primate behavioral ecology that contain data generated from both provisioned and nonprovisioned groups.

Adaptations to a cold climate promoted social evolution in Asian colobine primates.

The biological mechanisms that underpin primate social evolution remain poorly understood. Asian colobines display a range of social organizations, which makes them good models for investigating social evolution. By integrating ecological, geological, fossil, behavioral, and genomic analyses, we found that colobine primates that inhabit colder environments tend to live in larger, more complex groups. Specifically, glacial periods during the past 6 million years promoted the selection of genes involved in cold-related energy metabolism and neurohormonal regulation. More-efficient dopamine and oxytocin pathways developed in odd-nosed monkeys, which may have favored the prolongation of maternal care and lactation, increasing infant survival in cold environments. These adaptive changes appear to have strengthened interindividual affiliation, increased male-male tolerance, and facilitated the stepwise aggregation from independent one-male groups to large multilevel societies.

Wild gibbons plan their travel pattern according to food types of breakfast.

Planning for the future is a complex skill that is often considered uniquely human. This cognitive ability has never been investigated in wild gibbons (Hylobatidae). Here we evaluated the movement patterns from sleeping trees to out-of-sight breakfast trees in two groups of endangered skywalker gibbons (Hoolock tianxing). These Asian apes inhabit a cold seasonal montane forest in southwestern China. After controlling for possible confounding variables including group size, sleeping pattern (sleep alone or huddle together), rainfall and temperature, we found that food type (fruits or leaves) of the breakfast tree was the most important factor affecting gibbon movement patterns. Fruit breakfast trees were more distant from sleeping trees compared with leaf trees. Gibbons left sleeping trees and arrived at breakfast trees earlier when they fed on fruits compared with leaves. They travelled fast when breakfast trees were located further away from the sleeping trees. Our study suggests that gibbons had foraging goals in mind and plan their departure times accordingly. This ability may reflect a capacity for route-planning, which would enable them to effectively exploit highly dispersed fruit resources in high-altitude montane forests.

Effects of food availability and climate on the activity budget of Shortridge's langur (Trachypithecus shortridgei) in the Drung Valley, Gaoligong Mountains, China.

Food availability and climate represent environmental factors that affect species' social behavior, ranging patterns, diet, and activity budget. From August 2012 to September 2013, we examined the effects of seasonal changes in food availability, temperature, and rainfall on the diet and behavioral ecology of Shortridge's langur (Trachypithecus shortridgei) an Endangered primate species inhabiting moist evergreen broadleaf forests in the Eastern Himalayas. Our field site represents the northernmost latitudinal distribution of this species. Data were collected using scan sampling at 10 min intervals, and analyzed based on generalized linear models. The results indicate that the langurs experienced two feeding peaks (9:00 and 17:00) and two traveling peaks (10:00 and 19:00) during each day. Periods of rest, mainly occurred between 10:00 and 13:00, and overnight. Feeding accounted for 38.5% of the daily activity budget, followed by resting (35%), traveling (24.5%), and socializing (2%). During periods when young leaves were most available, the langurs increased feeding time on young leaves (35% vs. 4%). During periods of maximum fruit availability, the langurs decreased total time spent feeding (36.6% vs. 40.4%), devoted more time to traveling (28.1% vs. 21%), and increased time spent consuming fruit (49.1% vs. 11.8%). During the winter, the langurs increased their consumption of mature leaves (44.5%) and reduced time spent traveling (20.2% vs. 25.4%). Overall, time spent resting was greatest in the spring (47.5%), time spent feeding was greatest during the summer (51.1%), and time spent in traveling was greatest in the autumn (33.2%). The frequency of social interactions remained relatively constant throughout the year. Foraging effort was greatest in the summer, when fruits dominated the diet. Like other species of temperate langurs, T. shortridgei devoted less time to resting, more time to feeding, and was characterized by a greater year-round foraging effort than tropical/subtropical langurs.

Comparative susceptibility of SARS-CoV-2, SARS-CoV, and MERS-CoV across mammals.

Exploring wild reservoirs of pathogenic viruses is critical for their long-term control and for predicting future pandemic scenarios. Here, a comparative in vitro infection analysis was first performed on 83 cell cultures derived from 55 mammalian species using pseudotyped viruses bearing S proteins from SARS-CoV-2, SARS-CoV, and MERS-CoV. Cell cultures from Thomas's horseshoe bats, king horseshoe bats, green monkeys, and ferrets were found to be highly susceptible to SARS-CoV-2, SARS-CoV, and MERS-CoV pseudotyped viruses. Moreover, five variants (del69-70, D80Y, S98F, T572I, and Q675H), that beside spike receptor-binding domain can significantly alter the host tropism of SARS-CoV-2. An examination of phylogenetic signals of transduction rates revealed that closely related taxa generally have similar susceptibility to MERS-CoV but not to SARS-CoV and SARS-CoV-2 pseudotyped viruses. Additionally, we discovered that the expression of 95 genes, e.g., PZDK1 and APOBEC3, were commonly associated with the transduction rates of SARS-CoV, MERS-CoV, and SARS-CoV-2 pseudotyped viruses. This study provides basic documentation of the susceptibility, variants, and molecules that underlie the cross-species transmission of these coronaviruses.

Habitat restoration is the greatest challenge for population recovery of Hainan gibbons (Nomascus hainanus).

Hainan gibbons are among the world's most critically endangered primates, with a remaining population of only 35 individuals distributed across 5 social groups in the Bawangling Branch of the Hainan Tropical Rainforest National Park, China. Habitat conversion and forest fragmentation over the past 40 years have reduced their geographical distribution by 95%. In the absence of a quantitative assessment of the availability of remaining suitable habitat, it is unclear whether this species can survive to the end of this century. We used behavioral observations, ArcGIS, remote sensing, stereo optical imagery, and MaxEnt modeling to identify patterns of Hainan gibbon range use and compare changes in the distribution of suitable forest types and areas of forest fragmentation over the past 20 years (2000-2020). The results indicate that the combined range of the 5 extant Hainan gibbon groups totaled 14.89 km2 . The home range of the smallest group (Group E, 3 individuals) was 1.51 km2 , which likely represents the minimum home range size for this species. The remaining area of highly suitable and moderately suitable habitat totals 26.9 km2 . However, habitat connectivity across the gibbon range is very low (less than 0.5), limiting the ability of Hainan gibbons to move between forest patches. The results of this study indicate that the availability of suitable habitat in Bawangling is insufficient to allow for future Hainan gibbon population growth. Therefore, immediate action must be taken to restore, reforest, and establish ecological corridors to reconnect areas of suitable habitat for these critically endangered gibbons.

Global importance of Indigenous Peoples, their lands, and knowledge systems for saving the world's primates from extinction.

Primates, represented by 521 species, are distributed across 91 countries primarily in the Neotropic, Afrotropic, and Indo-Malayan realms. Primates inhabit a wide range of habitats and play critical roles in sustaining healthy ecosystems that benefit human and nonhuman communities. Approximately 68% of primate species are threatened with extinction because of global pressures to convert their habitats for agricultural production and the extraction of natural resources. Here, we review the scientific literature and conduct a spatial analysis to assess the significance of Indigenous Peoples' lands in safeguarding primate biodiversity. We found that Indigenous Peoples' lands account for 30% of the primate range, and 71% of primate species inhabit these lands. As their range on these lands increases, primate species are less likely to be classified as threatened or have declining populations. Safeguarding Indigenous Peoples' lands, languages, and cultures represents our greatest chance to prevent the extinction of the world's primates.

The faecal metabolome of black howler monkeys (Alouatta pigra) varies in response to seasonal dietary changes.

Mammals rely on the metabolic functions of their gut microbiota to meet their energetic needs and digest potentially toxic components in their diet. The gut microbiome plastically responds to shifts in host diet and may buffer variation in energy and nutrient availability. However, it is unclear how seasonal differences in the gut microbiome influence microbial metabolism and nutrients available to hosts. In this study, we examine seasonal variation in the gut metabolome of black howler monkeys (Alouatta pigra) to determine whether those variations are associated with differences in gut microbiome composition and nutrient intake, and if plasticity in the gut microbiome buffers shortfalls in energy or nutrient intake. We integrated data on the metabolome of 81 faecal samples from 16 individuals collected across three distinct seasons with gut microbiome, nutrient intake and plant metabolite consumption data from the same period. Faecal metabolite profiles differed significantly between seasons and were strongly associated with changes in plant metabolite consumption. However, microbial community composition and faecal metabolite composition were not strongly associated. Additionally, the connectivity and stability of faecal metabolome networks varied seasonally, with network connectivity being highest during the dry, fruit-dominated season when black howler monkey diets were calorically and nutritionally constrained. Network stability was highest during the dry, leaf-dominated season when most nutrients were being consumed at intermediate rates. Our results suggest that the gut microbiome buffers seasonal variation in dietary intake, and that the buffering effect is most limited when host diet becomes calorically or nutritionally restricted.

Disassociation of social and sexual partner relationships in a gibbon population with stable one-male two-female groups.

Adult males living in a one-male multi-female social group are expected to try to monopolize copulations with resident females to increase reproductive fitness. Gibbons have traditionally been described as living in monogamous groups, with the sole resident adult male assumed to sire all of the group's offspring. Here, we used microsatellite analyses and behavioral observations to examine rates of extra-group paternity (EGP) over 16 years in a population of crested gibbons (Nomascus concolor) that form stable and long-term one-male two-female social units. Forty percent of offspring (N = 14) were sired by extra-group males. To understand this high level of EGP, we tested whether inbreeding avoidance was related to EGP. Females who engaged in EGP did not show larger pairwise relatedness with their resident male compared to females who did not engage in EGP. Nevertheless, the standardized heterozygosity of EGP offspring was significantly higher than for offspring sired by the group's resident male. These results provide partial support for the inbreeding avoidance hypothesis. It appears that resident male crested gibbons are unable to monopolize resident females' matings. Our results indicate that long-term social partners are often distinct from sexual partners in this population. Clearly, the breeding system of crested gibbons is more flexible than previously thought, indicating a need for integrating long-term behavioral data and genetic research to re-evaluate gibbon social and sexual relationships derived from concepts of monogamy and pair-bonding.

Identifying the environmental and anthropogenic causes, distribution, and intensity of human rhesus macaque conflict in Nepal.

Reducing conflict between humans and wildlife is considered a top conservation priority. However, increasingly human-induced disturbances across natural landscapes have escalated encounters between humans and wildlife. In Nepal, forests have been destroyed, fragmented, and developed for human settlements, agricultural production, and urban centers for decades. As a result, human-wildlife conflict, in the form of crop-raiding, livestock predation, and injuries to humans and wildlife, is common throughout the country. In particular, crop-raiding by macaques is an increasingly common form of human-wildlife conflict. Rhesus macaques (Macaca mulatta) have been identified as a top ten crop-raiding wildlife species in Nepal. In order to better understand the nationwide distribution and intensity of human-rhesus macaque conflict (HRMC), we conducted an extensive literature review of reported incidences of HRMC during the period 2000 to 2021 in Nepal. We also created an online survey to obtain nationwide data on the location and severity of HRMC, and modeled the set of ecological factors that affect habitat suitability for rhesus macaques. An ensemble of three different species distribution model (SDM) algorithms were used to analyze these data. We found that almost 44% of Nepal's land area contains suitable habitat for rhesus macaques, with less than 8% of all suitable habitat located in protected national parks. As humans continue to alter and fragment natural landscapes, HRMC in Nepal has intensified. At present, nearly 15% of the country's land area in which human settlements are permitted, is characterized by moderate or high rates of HRMC. We argue that prioritizing programs of forest restoration, strategic management plans designed to connect isolated forest fragments with high rhesus macaque population densities, creating government programs that compensate farmers for income lost due to crop-raiding, and educational outreach that informs local villagers of the importance of conservation and protecting biodiversity, offer the most effective solutions to reduce HRMC in Nepal.

Diverse grouping and mating strategies in the Critically Endangered Hainan gibbon (Nomascus hainanus).

Understanding flexibility in the social structure and mating strategies of the world's last remaining population (35 individuals) of wild Hainan gibbons (Nomascus hainanus) is critical for developing effective management plans to aid in their population recovery. Three of the five remaining Hainan gibbon groups (A, B, and C) currently live in a social unit characterized by two or three adult males, two reproducing adult females, and offspring. A fourth group (D) contains one adult male, two adult females, and offspring, and Group E contains a single adult male-adult female pair with a young infant. In this study, we describe observations of copulations between multiple resident males and one of the two resident females in Group C. Group C is best described as a small multi-male/multi-female group. We found that this breeding female (F2) solicited copulations from two resident adult males (M1 and M2) on the same day, and also mated with each of these two males on different days. Resident males were not observed to interrupt the mating pair. Although factors such as a biased adult sex ratio, severe population disruption, and habitat degradation can help explain variation in group composition and mating strategies in Hainan gibbons, we argue that there exists considerable mating system variability across gibbon species, and that this variability offers important insights into male and female Hainan gibbon group structure and reproductive strategies.

Specialized digestive adaptations within the hindgut of a colobine monkey.

In mammal herbivores, fiber digestion usually occurs predominantly in either the foregut or the hindgut. Reports of mechanisms showing synergistic function in both gut regions for the digestion of fiber and other nutrients in wild mammals are rare because it requires integrative study of anatomy, physiology, and gut microbiome. Colobine monkeys (Colobinae) are folivorous, with high-fiber foods fermented primarily in their foreguts. A few colobine species live in temperate regions, so obtaining energy from fiber during the winter is essential. However, the mechanisms enabling this remain largely unknown. We hypothesized that such species possess specialized mechanisms to enhance fiber digestion in the hindgut and studied microbial and morphological digestive adaptations of golden snub-nosed monkeys (GSMs), Rhinopithecus roxellana. which is a temperate forest colobine from central China that experiences high-thermal-energy demands while restricted to a fibrous, low-energy winter diet. We tested for synergistic foregut and hindgut fiber digestion using comparisons of morphology, microbiome composition and function, and digestive efficiency. We found that the GSM colon has a significantly greater volume than that of other foregut-fermenting colobines. The microbiomes of the foregut and hindgut differed significantly in composition and abundance. However, while digestive efficiency and the expression of microbial gene functions for fiber digestion were higher in the foregut than in the hindgut, both gut regions were dominated by microbial taxa producing enzymes to enable active digestion of complex carbohydrates. Our data suggest that both the GSM foregut and hindgut facilitate fiber digestion and that an enlarged colon is likely an adaptation to accommodate high throughput of fiber-rich food during winter.

The 10th anniversary of the scientific description of the black snub-nosed monkey (Rhinopithecus strykeri): It is time to initiate a set of new management strategies to save this critically endangered primate from extinction.

Traditionally, the genus Rhinopithecus (Milne-Edwards, 1872, Primates, Colobinae) included four allopatric species, restricted in their distributions to China and Vietnam. In 2010, a fifth species, the black snub-nosed monkey (Rhinopithecus strykeri) was discovered in the Gaoligong Mountains located on the border between China and Myanmar. Despite the remoteness, complex mountainous terrain, dense fog, and armed conflict that characterizes this region, over this past decade Chinese and Myanmar scientists have begun to collect quantitative data on the ecology, behavior and conservation requirements of R. strykeri. In this article, we review the existing data and present new information on the life history, ecology, and population size of R. strykeri. We discuss these data in the context of past and current conservation challenges faced by R. strykeri, and propose a series of both short-term and long-term management actions to ensure the survival of this Critically Endangered primate species. Specifically, we recommend that the governments and stakeholders in China and Myanmar formulate a transboundary conservation agreement that includes a consensus on bilateral exchange mechanisms, scientific research and monitoring goals, local community development, cooperation to prevent the hunting of endangered species and cross-border forest fires. These actions will contribute to the long-term conservation and survival of this Critically Endangered species.

Principal Drivers and Conservation Solutions to the Impending Primate Extinction Crisis: Introduction to the Special Issue.

Nonhuman primates are facing an impending extinction crisis with over 65% of species listed as Vulnerable, Endangered, or Critically Endangered, and 93% characterized by declining populations. Primary drivers of primate population decline include deforestation, principally for industrial agriculture and the production of food and nonfood commodities, much of which is exported to wealthy consumer nations, unsustainable bushmeat hunting, the illegal pet trade, the capture of primates for body parts, expanding road and rail networks, mining, dam building, oil and gas exploration, and the threat of emerging diseases. Over the next several decades, human population increase, agricultural expansion, and climate change are expected to contribute significantly to the loss of additional suitable habitat and a reduction in the viability of local primate populations. If we are to avoid this impending extinction crisis, primate researchers must prioritize projects designed to mitigate the effects of habitat change on ecosystems health and biodiversity, and play a greater role in conservation and environmental policy by educating global citizens and political leaders. In addition, the international community will need to work with governments in primate habitat countries to expand the number of protected areas that contain primate species (94 primate species have < 10% of their range in protected areas). In this special issue of the International Journal of Primatology, we bring together researchers from a wide range of disciplines to examine the current and future threats to primate population persistence, and present local, country, and regional solutions to protect primate species.