Variation in monthly and seasonal elevation use impacts behavioral and dietary flexibility in Rhinopithecus bieti.

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.

Surviving at the highest and coldest: Nutritional and chemical components of fallback foods for Yunnan snub-nosed monkeys.

Fallback foods (FBF), categorized into staple and filler types, are suboptimal food sources chosen by animals in response to a scarcity of preferred food items during specific periods. Using lichens as FBF by Yunnan snub-nosed monkeys (Rhinopithecus bieti) represents a distinctive ecological adaptation and evolutionary development within nonhuman primates. This study delves into the annual dietary choices of the species to address issues, elucidate the nutritional value, and understand the ecological significance of lichens for this primate species, which resides at the highest altitudes and experiences the coldest weather among global primates. The findings reveal that the lichens consumed by the monkeys serve as the staple FBF, with Bryoria spp. and Usnea longissima being the primary dietary species. The former is the preferred choice, providing higher digestible fiber (neutral detergent fiber) levels but lower tannin, fat, ADF, and energy levels. During the dry season, lichens dominate as the monkeys' primary food and nutritional resources. In the wet season, they act as a fundamental food selection rather than an ideal dietary choice, substituting nutrients from fruits, seeds, and leaves. Compared to other Asian colobine counterparts, this species exhibits the highest lichen consumption but the lowest proportions of leaves, flowers, and seeds. This study provides valuable evidence and information for developing or amending conservation strategies and guidelines for the dietary management of captive breeding of monkeys, one of the world's critically endangered primate species.

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.

Ontogenetic Development of Sexual Dimorphism in Body Mass of Wild Black-and-White Snub-Nosed Monkey (Rhinopithecus bieti).

Sexual dimorphism exists widely in animals, manifesting in different forms, such as body size, color, shape, unique characteristics, behavior, and sound. Of these, body mass dimorphism is the most obvious. Studies of evolutionary and ontogenetic development and adaptation mechanisms of animals' sexual dimorphism in body mass (SDBM), allow us to understand how environment, social group size, diet, and other external factors have driven the selection of sexual dimorphism. There are fewer reports of the ontogenetic development of sexual dimorphism in body mass in Rhinopithecus. This study explores the ontogenetic development pattern of SDBM in wild black-and-white snub-nosed monkeys (R. bieti), and the causes resulting in extreme sexual dimorphism compared to other colobines. A significant dimorphism with a ratio of 1.27 (p < 0.001) appears when females enter the reproductive period around six years old, reaching a peak (1.85, p < 0.001) when males become sexually mature. After the age of eight, the SDBM falls to 1.78, but is still significant (p < 0.001). The results also indicate that males had a longer body mass growth period than females (8 years vs. 5 years); females in larger breeding units had a significantly higher SDBM than those in smaller ones (2.12 vs. 1.93, p < 0.01). A comparative analysis with other colobines further clarifies that Rhinopithecus and Nasalis, which both have multilevel social organization, have the highest degree of SDBM among all colobines. The large SDBM in R. bieti can be explained through Bergman's and Rensch's rules. Overall, environmental adaptation, a distinctive alimentary system, and a complex social structure contribute to R. bieti having such a remarkable SDBM compared to other colobines. In addition, we found that females' choice for males may not be significantly related to the development of SDBM.

Taxonomy on three allied genera within Arcypterini (Orthoptera: Acrididae) from Qinghai-Xizang Plateau, China.

The generic diagnosis of three allied genera, Leuconemacris Zheng, 1988, Asulconotoides Liu, 1984 and Asulconotus Ying, 1974, are compared and redescribed. Four new species, Leuconemacris acuminata, sp. nov., L. xinlongensis, sp. nov., L. muliensis, sp. nov. and Asulconotus acarinatus, sp. nov. are described and illustrated. Two new combinations are established: Asulconotoides asulcata (Zheng, 1988) comb. nov. = Leuconemacris asulcata Zheng, 1988 and Asulconotoides microptera (Zheng, 1988), comb. nov. = Leuconemacris microptera Zheng, 1988. All updated keys to genera and species are given.

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.

Complete mitochondrial genome and phylogenetic analysis of Ixodes ovatus (Acari: Ixodidae).

Ixodes ovatus is referred to as an obligatory blood-sucking ectoparasite that is capable to infest both humans and animals. In the present study, the complete mitochondrial genome of I. ovatus was sequenced and analyzed using next-generation sequencing (NGS) technology. With a size of 14,520 bp, the entire mitogenome contains 37 genes including 13 protein-coding genes (PCGs), 22 transfer RNAs (tRNAs), 2 ribosomal RNAs (rRNAs), and 3 control regions (D-loops). Based on the 13 PCGs nucleotide sequences, the phylogenetic relationship of I. ovatus was analyzed using Maximum-likelihood. As suggested by the results of the obtained phylogenety, I. ovatus is most closely associated with Ixodes hexagonus. This study is expected to promote further studies on the evolution of Ixodidae.

Positional behavior and canopy use of black snub-nosed monkeys Rhinopithecus strykeri in the Gaoligong Mountains, Yunnan, China.

Studies on positional behavior and canopy use are essential for understanding how arboreal animals adapt their morphological characteristics and behaviors to the challenges of their environment. This study explores canopy and substrate use along with positional behavior in adult black snub-nosed monkeys Rhinopithecus strykeri, an endemic, critically endangered primate species in Gaoligong Mountains, southwest China. Using continuous focal animal sampling, we collected data over a 52-month period and found that R. strykeri is highly arboreal primarily using the high layers of the forest canopy (15-30 m), along with the terminal zone of tree crowns (52.9%), medium substrates (41.5%), and oblique substrates (56.8%). We also found sex differences in canopy and substrate use. Females use the terminal zones (56.7% versus 40.4%), small/medium (77.7% versus 60.1%), and oblique (59.9% versus 46.5%) substrates significantly more than males. On the other hand, males spend more time on large/very large (39.9% versus 22.3%) and horizontal (49.7% versus 35.2%) substrates. Whereas both sexes mainly sit (84.7%), and stand quadrupedally (9.1%), males stand quadrupedally (11.5% versus 8.3%), and bipedally (2.9% versus 0.8%) more often than females. Clamber, quadrupedalism, and leap/drop are the main locomotor modes for both sexes. Rhinopithecus strykeri populations never enter canopies of degenerated secondary forest and mainly use terminal branches in the middle and upper layers of canopies in intact mid-montane moist evergreen broadleaf forest and hemlock coniferous broadleaf mixed forests across their habitat.

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.

Faecalibacter rhinopitheci sp. nov., a bacterium isolated from the faeces of Rhinopithecus bieti.

A novel Gram-stain-negative strain, WQ 117T, isolated from the faeces of Rhinopithecus bieti collected at Yunnan Snub-nosed Monkey National Park, Yunnan province, PR China, was subjected to a polyphasic taxonomic study. The results of phylogenetic analysis based on 16S rRNA gene sequences indicated that the isolate represented a member of the genus Faecalibacter, sharing 97.64 % sequence similarity with the type strain Faecalibacter macacae YIM 102668T. The G+C content of the genomic DNA of WQ117T was 30.5 mol%. The predominant isoprenoid quinone was MK-6. The major cellular fatty acids was iso-C15 : 0. The whole genome average nucleotide identity (gANI) values and the digital DNA-DNA hybridization values between WQ 117T and YIM 102668T were 79.66 % and 22.20 %, respectively. Growth occurred at 0-50 °C (optimally at 28-35 °C), pH 7.0-9.0 (optimally at pH 8.0) and with 0-2 % (w/v) NaCl (optimally without NaCl). On the basis of the taxonomic evidence, a novel species, Faecalibacter rhinopitheci sp. nov., is proposed. The type strain is WQ 117T (=KCTC 82394T=CCTCC AA 2020027T).

A Review of Two Decades of Conservation Efforts on Tigers, Co-Predators and Prey at the Junction of Three Global Biodiversity Hotspots in the Transboundary Far-Eastern Himalayan Landscape.

Addressing the effects of human-caused habitat destruction on free-ranging threatened large carnivores requires actions that go 'beyond borders' in conserving and protecting their habitat and prey base. In this review, we compiled information from available literature on 20 years of conservation efforts aimed at tigers, co-predators, and their prey in the Far-Eastern Himalayan Landscape that is situated at the confluence of three global biodiversity hotspots covering parts of India, Myanmar, and China. The vast area of the proven biodiversity-rich forested landscape is highly suitable for long-term survival of carnivores, such as tigers. Habitat loss, ritual hunting, commercial exploitation, and poaching are the prevailing threats that have resulted in low tiger, co-predator, and prey population densities. Studies suggest that tiger presence is confined to a few areas, while other tiger populations have been extirpated across most parts of the landscape. Past research also suggests that the landscape holds low abundance of diverse prey species richness (n = 22), and urgent conservation measures are required to improve their habitat and numbers. This calls for greater regional and transboundary co-operation on research and knowledge sharing, conservation awareness programs for locals, and cross-border co-operation on wildlife monitoring. Strict policies are also required to enable PA managers to develop strategic plans to conserve large predators and protect their habitats and corridors.

An automatic method for removing empty camera trap images using ensemble learning.

Camera traps often produce massive images, and empty images that do not contain animals are usually overwhelming. Deep learning is a machine-learning algorithm and widely used to identify empty camera trap images automatically. Existing methods with high accuracy are based on millions of training samples (images) and require a lot of time and personnel costs to label the training samples manually. Reducing the number of training samples can save the cost of manually labeling images. However, the deep learning models based on a small dataset produce a large omission error of animal images that many animal images tend to be identified as empty images, which may lead to loss of the opportunities of discovering and observing species. Therefore, it is still a challenge to build the DCNN model with small errors on a small dataset. Using deep convolutional neural networks and a small-size dataset, we proposed an ensemble learning approach based on conservative strategies to identify and remove empty images automatically. Furthermore, we proposed three automatic identifying schemes of empty images for users who accept different omission errors of animal images. Our experimental results showed that these three schemes automatically identified and removed 50.78%, 58.48%, and 77.51% of the empty images in the dataset when the omission errors were 0.70%, 1.13%, and 2.54%, respectively. The analysis showed that using our scheme to automatically identify empty images did not omit species information. It only slightly changed the frequency of species occurrence. When only a small dataset was available, our approach provided an alternative to users to automatically identify and remove empty images, which can significantly reduce the time and personnel costs required to manually remove empty images. The cost savings were comparable to the percentage of empty images removed by models.

Human activities and elevational constraints restrict ranging patterns of snub-nosed monkeys in a mountainous refuge.

Both natural conditions and anthropogenic factors affect the survivability, distribution, and population density of wildlife. To understand the extent and how these factors drive species distributions, a detailed description of animal movement patterns in natural habitats is needed. In this study, we used satellite telemetry to monitor elevational ranges favored by endangered golden snub-nosed monkeys (Rhinopithecus roxellana), in the Qinling Mountains, central China. We investigated the abundance and distribution of food resources through sampling vegetation quadrats at different elevations and sampled anthropogenic activities using field surveys. Our results indicated that although there was no significant variation in food resources between low- (<1500 m) and middle-elevations (1500-2200 m), monkeys were found most often in areas above 1500 m, where there was less anthropogenic development (e.g. houses and roads); however, monkeys rarely ranged above 2200 m and had limited food availability at this altitude. There was limited human disturbance at this elevation. We suggest that both human activity and ecological constraints (i.e. food resources) have considerable effects on elevational use of R. roxellana in the Qinling Mountains. This study highlights the critical roles these factors can play in shaping the vertical distribution of high-altitude primates. This research provides useful insights for habitat-based conservation plans in which human disturbance management and habitat restoration should be prioritized.

Male and female birth attendance and assistance in a species of non-human primate (Rhinopithecus bieti).

Birth attendance, or midwifery service, is an important characteristic in human evolution, and has been argued to separate our lineage from other taxa in the animal kingdom. Recent studies, however, indicate that similar or analogous behaviors also may occur in a small number of nonhuman primate species. Here, we report the first case of both male and female attendance and female birth assistance in a wild species of nonhuman primate, the black-and-white snub-nosed monkey (Rhinopithecus bieti). At our field site in Yunnan, China we observed a diurnal birth event in which the leader male of a one-male unit (OMU) remained in close- proximity (0-2 m) to the parturient, groomed her, and remained vigilant over a five hour pre- and postpartum period. In addition, a multiparous female member of the OMU also remained in close proximity to the soon-to-be mother, helped to pull the neonate from the birth canal, took the neonate from the new mother within 15 s of the birth, held the infant for 20 min, and then severed the umbilical cord. For the next several days the leader male traveled in close-proximity to the new mother and four days after the birth event, we observed him to share food with her. Given that diurnal births are extremely rare in this primate species; it remains unclear the degree to which the events we observed commonly occur during nighttime births. We argue that adult male and female black-and-white snub-nosed monkeys are highly attracted to young infants, and birth attendance and birth assistance in this, and certain other primate species, may play a critical role in maternal and infant survivorship.

Preliminary study on dietary selection in Shortridge's langurs ( Trachypithecus shortridgei) from China.

Understanding dietary selection and feeding strategies is important for the conservation and management of endangered primate species. Here, we conducted a preliminary study on the diet and feeding behavior of endangered Shortridge's langurs ( Trachypithecus shortridgei) within the Drung River Valley (Dulongjiang) in southwestern China. The study site lies at a high latitude (N27°47.5') and elevation (1 900 m a.s.l.) and is characterized by substantial annual rainfall (2 745.1 mm). From August 2012 to September 2013, we observed five groups of langurs and analyzed their overall food composition and dietary variation in spring and autumn. To understand their dietary adaptations to the distinctive habitat of the Drung River Valley, we also compared the diet of Shortridge's langurs to that of other Trachypithecus species inhabiting different environments. Results indicated that T. shortridgei fed on 52 plant species, 23 of which each accounted for ≥1% of their annual feeding time. Their primary dietary components included leaves (46.2%, young, mature, and petioles), fruits (28.7%, unripe 17.6%, ripe 11.1%), and mosses (10.2%). The langurs mainly consumed mature (34.2%) and young leaves (27.5%) in spring and ripe fruits (39.4%) and mature leaves (24.7%) in autumn. Two species of moss ( Macrothamnium macrocarpum and Scapania verrucosa, 21.2% of annual feeding time), which are usually found growing together on cliffs, played a relatively important role in the diet of T. shortridgei. The langurs mainly consumed ripe fruits of Saurauia napaulensis (7.1%) and Dendropanax burmanicus (7.1%), which were abundant at lower elevations. Trachypithecus species in temperate forests consumed more fruits and seeds but fewer leaves (similar mature leaves but fewer young leaves) than those species in tropical forests, which may be related to their availability and abundance. Compared to Trachypithecus species in temperate forests, the higher proportion of mosses and mature leaves but fewer young leaves in the annual diet of T. shortridgei are likely a response to the distinctive Drung River Valley habitat. Therefore, conservation of the main food plants of this threatened species could be vital for its survival and conservation management.

Cafeteria-style feeding trials provide new insights into the diet and nutritional strategies of the black snub-nosed monkey (Rhinopithecus strykeri): Implications for conservation.

Anthropogenic changes and fragmentation of natural habitats often exert a negative effect on resource availability and distribution, and the nutritional ecology and feeding behavior of nonhuman primates. The goals of this study are to examine food choice and to identify the nutritional profile of foods consumed by the Critically Endangered black snub-nosed monkey (Rhinopithecus strykeri). To accomplish our study goals, we presented cafeteria-style feeding trials of fresh food items collected in the home range of wild black snub-nosed monkeys to the only two captive R. strykeri, and compared the nutritional profiles of the leafy foods (buds, young, and mature leaves, 100 i23tems from 70 plant species) selected with those avoided (54 items from 48 plant species). Overall, the results indicate that captive R. strykeri selected foods that were higher in moisture (Mo; 77.7%), crude protein (CP; 21.2%), total nonstructural carbohydrates (TNC; 34.9%), and phosphorus (P; 0.37%) while tending to avoid foods with a neutral detergent fiber (NDF) content of greater than 46.8%. Leaves collected in autumn and selected by the monkeys were characterized by a slightly higher amount of metabolizable energy (ME) than those rejected (1,350 kJ/100 g vs. 1,268 kJ/100 g). In contrast, the protein content of foods collected and consumed during the spring was greater (22.9%) than in autumn (16.4%). Random Forests modeling, an ensemble learning method, indicated that the proportion of Mo, NDF, ME, CP, P, and TNC were among the most important factors in predicting which items were consumed by the captive R. strykeri during spring and autumn. On the basis of the nutritional profile of foods consumed across the two seasons, we identified 18 nutrient-rich native plant species that we recommend for use in ex- and in-situ conservation management and reforestation programs to provide long-term access to a nutritionally adequate diet.

Correction to: Review of GPS collar deployments and performance on nonhuman primates.

In the original publication of the article, figure 1 was wrongly published as a duplication.

Review of GPS collar deployments and performance on nonhuman primates.

Over the past 20 years, GPS collars have emerged as powerful tools for the study of nonhuman primate (hereafter, "primate") movement ecology. As the size and cost of GPS collars have decreased and performance has improved, it is timely to review the use and success of GPS collar deployments on primates to date. Here we compile data on deployments and performance of GPS collars by brand and examine how these relate to characteristics of the primate species and field contexts in which they were deployed. The compiled results of 179 GPS collar deployments across 17 species by 16 research teams show these technologies can provide advantages, particularly in adding to the quality, quantity, and temporal span of data collection. However, aspects of this technology still require substantial improvement in order to make deployment on many primate species pragmatic economically. In particular, current limitations regarding battery lifespan relative to collar weight, the efficacy of remote drop-off mechanisms, and the ability to remotely retrieve data need to be addressed before the technology is likely to be widely adopted. Moreover, despite the increasing utility of GPS collars in the field, they remain substantially more expensive than VHF collars and tracking via handheld GPS units, and cost considerations of GPS collars may limit sample sizes and thereby the strength of inferences. Still, the overall high quality and quantity of data obtained, combined with the reduced need for on-the-ground tracking by field personnel, may help defray the high equipment cost. We argue that primatologists armed with the information in this review have much to gain from the recent, substantial improvements in GPS collar technology.

The effective use of camera traps to document the northernmost distribution of the western black crested gibbon in China.

Gibbons represent a highly successful radiation of four genera and 20 species of Asian apes that, in response to recent habitat fragmentation and deforestation, are threatened with extinction. China has six species of gibbons, each of which is critically endangered. We present new biogeographical information on the distribution of the black crested gibbon (Nomascus concolor). Four subspecies of N. concolor have been described: three of them are present east of the Mekong River (Nomascus concolor jingdongensis, N. c. concolor and N. c. lu); and another is found west of the Mekong River (N. c. furvogaster). In addition, there has been speculation that gibbons exist in the Biluo Snow Mountains, between the Mekong and Salween basins. To clarify the biogeography of this species, from April 2011 to January 2012 and from January 2016 to September 2018, we conducted interviews with local villagers, completed line transect surveys, monitored gibbon calls, and placed 30 camera traps in the forest canopy. On October 30, 2016, we recorded gibbon's calls. On July 5, 2016, our camera traps obtained one image of a male gibbon, and on February 1 and 8, 2017, we captured two independent images of an adult female gibbon on Zhiben Mountains. Based on the black crest on the head, clearly visible in the photographs, the gibbons are N. c. furvogaster. Evidence from interviews and survey records indicate that N. c. furvogaster once was present in the Zhiben Mountains, at an altitude of between 2000 and 2700 m. Between 1990 and 2000, some 6-7 groups still existed in Caojian, Laowo and adjacent areas. Unfortunately, in the absence of an effective conservation strategy, the population was extirpated by hunters. The remaining forest in the Zhiben Mountains is highly fragmented, and most of the suitable habitat for gibbons has been lost. Therefore, we expect that this newly found gibbon population is under extreme anthropogenic pressure. It is imperative that further investigations of this gibbon population be conducted immediately, and that the local and national governments implement effective conservation plans, including educating the local communities to protect this critically endangered primate population.