Population Of Monkeys Research Articles

Gastrointestinal parasites of blue monkeys (Cercopithecus mitis) and grey‐cheeked mangabeys (Lophocebus albigena) at the Ngogo Research Site in Kibale National Park, Uganda

AbstractThere has been persistent decline in blue monkey (Cercopithecus mitis) population at Ngogo research site in the past 40 years for no clear reasons. In contrast, the populations of other nonhuman primates like the grey‐cheeked mangabeys (Lophocebus albigena) which share identical home ranges with blue monkeys have not been obviously affected. However, stakeholders attribute this decline to gastrointestinal parasitic diseases, hence the need to determine the profile of parasitic infections in blue monkeys and compare them to that of grey‐cheeked mangabeys within a shared home range. Faecal samples (n = 241) were subjected to diagnostic tests, namely sodium nitrate floatation and formol‐ether sedimentation before microscopic examination. 227 (94%) samples were parasite positive; six protozoa and 21 helminths were present. This implies that Ngogo hosts a high diversity of parasites which poses health risks to nonhuman primates. There was no significant statistical difference in the prevalence of the overall main pathogenic parasites between the two studied nonhuman primate species. Therefore, gastrointestinal parasites may not be the obvious cause of the proclaimed blue monkey population decline at Ngogo research site.

Tourism may trigger physiologically stress response of a long-term habituated population of golden snub-nosed monkeys.

Tourism may trigger physiologically stress response of a long-term habituated population of golden snub-nosed monkeys.

Forest fragmentation and defaunation drive an unusual ecological cascade: Predation release, monkey population outburst and plant demographic collapse

Anthropogenic habitat fragmentation combined with differential defaunation triggers complex trophic cascades. Here we test a Fragmentation-Defaunation Cascade Hypothesis by examining how a medium-sized monkey population outbreak, occurring in a predator-free forest fragment, lead to the decline of a dominant plant. We computed long-term population dynamics of Euterpe edulis (“palmito”) plants in a Brazilian Atlantic Forest landscape, where the palmito predator, capuchin monkey, becomes hyper-abundant in fragments devoid of monkey predators. Palmito plants (N = 1193) were marked and measured to define stage (height and diameter) categories in 2005, and then annually censused (2006–2015). Newly recruited plants within plots were marked and monitored throughout the 10-year period. Lefkovitch matrices for each transition year, population growth rate (λ), elasticity, and plant stage distribution showed a strong trend of demographic decline due to monkey lethal consumption of palm hearts. Indeed, λ calculations revealed that, by the end of the study period, palmito population was decreasing by 34% annually. A major shift in plant stage distribution occurred, in which the population became increasingly dominated by infants, while reproductives continuously declined, indicating that palmito will soon become extinct in this predator-free fragment. We conclude that differential defaunation in a forest fragment resulted insmall- and medium-sized mammal outbreaks negatively impacting the demography of a previously dominant host plant population. We posit that fragmentation-selective defaunation can disrupt animal communities, driving cascading effects which include plant demographic collapse and, potentially, severely altered forest community structure.

Multiple Resource Use Strategies and Resilience of a Socio-Ecosystem in a Natural Protected Area in the Yucatan Peninsula, Mexico

As the world faces unprecedented ecological and social changes, there is a need to better understand the complex dynamics of social-ecological systems (SES) and the mechanisms that underlie their resilience. In Mexico, Natural Protected Areas (NPAs) constitute complex SES as they are generally established on territories that different peoples have historically inhabited and managed. They generally manage their resources following a multiple use strategy (MUS), which involves local traditional agricultural practices and has been proposed as a resilience-enhancing mechanism. In this paper we study the MUS as practiced by the Yucatec Maya communities that inhabit the NPA Otoch Ma’ax Yetel Kooh and its buffer zone in the Yucatan Peninsula, Mexico. Due to the restrictions imposed by the decree of the reserve and the growth of tourism in the region, some of these communities have started to abandon the MUS and specialize on tourism-related activities. To study the consequences of these changes and to better understand the mechanisms by which the MUS may enhance the resilience of this SES, we built an evidence-based dynamical computational model that allows us to explore different virtual scenarios. The model, through the incorporation of agent-based and boolean network modelling, explores the interaction between the forest, the monkey population and some productive activities done by the households (milpa agriculture, ecotourism, agriculture, charcoal production). We calibrated the model, explored its sensibility, compared it with empirical data and simulated different management scenarios. Our results support the hypothesis that the MUS enhances the resilience of this SES in terms of income and food availability, as it increases the system’s response diversity and functional redundancy, thus reducing income variability and increasing the resistance to natural and anthropogenic disturbances. We also identify other possible mechanisms related with the MUS that provide a more nuanced understanding of the resilience of this SES. Our study, in addition to highlighting the importance of local management practices for resilience, also puts forward a novel integration of diverse mathematical formalisms and illustrates how computational modeling and a systems perspective are effective means of integrating and synthesizing information from different sources.

Habitat suitability of Proboscis monkey (Nasalis larvatus) in Berau Delta, East Kalimantan, Indonesia

The proboscis monkey (Nasalis larvatus) is an endemic species to Borneos’ island and is largely confined to mangrove, riverine, and swamp forest. Most of their habitat is outside the conservation due to degraded and habitat converted. Habitat loss is a significant threat to a decreased in the monkey's population. Berau Delta is an unprotected habitat of proboscis monkey, lacking in attention and experiencing a lot of disturbances. This study was conducted on April – August 2019; with aims of the study is to determine Species Distribution Modeling (SDM) for identifying proboscis monkey habitat suitability in Delta Berau, East Kalimantan. The MaxEnt algorithm was used to produce a habitat suitability map based on this species’ occurrence records and environmental predictors. We built the models using 208 points of proboscis monkey presence and 12 environment variables within the study area. Model performance was assessed by examining the area under the curve. The variables most influencing the habitat suitability model were the riverine habitat (60.9%), distance from the pond (16.0%), and distance from the coastline (5.2%). The proboscis monkey suitable habitat is only 9.32% (8,726.58 ha) from 93,631.41 ha total area. The appropriate habitat areas are Sapinang Island, Bungkung Island, Sambuayan Island, Saodang Kecil Island, Besing Island, Lati River, Bebanir Lama, Batu-Batu, and Semanting Bay. We provide some suggestions for the proboscis monkey conservation, which are local protection of uninhabited islands, participatory ecotourism management, and company involvement in protection and management efforts.

Evaluating extinction debt in fragmented forests: the rapid recovery of a critically endangered primate

AbstractFragmented tropical forests can be highly dynamic, with the spatial configuration of forest patches changing through time. Yet, the lack of longitudinal studies limits our understanding of how patch dynamics affect biodiversity, especially when there is a time lag in species extinctions (extinction debt). We assessed how temporal changes in patch size, shape complexity and isolation affect populations of the Mexican howler monkey (Alouatta palliata mexicana), hypothesizing that we would find an extinction debt in this relatively long‐lived species. We assessed patch occupancy, subpopulation size and immature‐to‐female ratio in 39 forest patches from Los Tuxtlas, Mexico, in both 2001 and 2013. To identify time‐lag responses to habitat disturbance, we related demographic attributes in 2013 to patch metrics in 2001 and 2013 and tested whether primate subpopulations were better predicted by current or historical patch characteristics. We also assessed how changes in patch metrics affected each demographic attribute between 2001 and 2013. Patch size and shape complexity increased over time, whereas isolation decreased. These positive spatial changes were accompanied by a 1.6‐fold increase in mean subpopulation size over the same period. In addition, occupancy and immature‐to‐female ratio were similarly related to patch attributes in both years, suggesting that there is no extinction debt. Our findings are ‘good news’, suggesting that forest recovery over a relatively short period can promote the recovery of this Critically Endangered taxon. They also highlight the importance of preventing forest loss and promoting forest regeneration in human‐modified tropical landscapes.

Adding another piece to the southern African Cercopithecus monkey phylogeography puzzle

The taxonomy and number of Cercopithecus monkey radiation events in southern Africa are still debated. To date, genetic studies have largely been limited to single specimens per taxon and a scattered geographical distribution. A recent study focusing on South African Cercopithecus monkeys showed that populations can be divided into three distinct genetic entities. Our current study aims to add new mtDNA and microsatellite data from a coastal population (Vamizi Island) in Mozambique to compare to existing data from South Africa. Our additional data allowed analysis of the number and timing of radiation events of Cercopithecus monkeys in southern Africa. Here we propose the occurrence of a single, north-south radiation event during the mid-Pleistocene along the Afromontane forest belt and that after the Last Glacial Maximum, samango populations reradiated into (re)established coastal forests on a more local scale. Our population genetic data support this pattern for both Mozambican, as well as South African samango monkey populations. By including mtDNA sequence data from Cercopithecus across Africa, we also discuss the hypothesis that the ‘Kingdon Line’ may explain the divergence of two major species in Africa within the C. mitis/nictitans group: C. albogularis and C. mitis.

Diversity analysis and an updated list of mosquitoes (Diptera: Culicidae) found in Cantareira State Park, São Paulo, Brazil

Cantareira State Park (CSP) is located in the Metropolitan Region of São Paulo, one of the most densely populated areas on the planet. Recently, a yellow-fever epidemic practically annihilated the howler monkey population in this park, and human infections were reported in the vicinity. As simian and human plasmodia also circulate in CSP, the present study sought to provide an update on the mosquito fauna in this park, including an analysis of the diversity in areas with different degrees of conservation and a comparison of the yields achieved with different collection techniques. From October 2015 to April 2017, adult mosquitoes were collected with CDC traps, hand-held battery-powered aspirators and Shannon traps, and larvae and pupae were collected with larval dippers and suction samplers in natural and artificial breeding sites. In total, 11,038 specimens distributed in 103 taxa represented by 16 genera were collected. Both the observed species richness and diversity were greater in the environments with the highest degree of preservation. The ‘wild’ (most preserved) area in CSP had the greatest species richness, followed by the transition area and human-impacted area. The estimated richness indicated that the three environments may have a greater number of species than observed in this study, and Sorensen's index showed that the average degree of similarity varies little between areas. In the inventory of local species, the Shannon trap was the most efficient collection technique for adult mosquitoes, and the suction sampler the most efficient for immatures. The results highlight the increase in the number of different taxa collected as different mosquito capture techniques were included, confirming the importance of using several strategies to sample the local mosquito fauna satisfactorily when exploring a greater number of ecotopes. CSP is a refuge and shelter for native and introduced mosquito species where new biocenoses including pathogens, vertebrate hosts and vectors can form, allowing zoonotic outbreaks in the local human population to occur.

Positively selected variants in functionally important regions of TLR7 in Alouatta guariba clamitans with yellow fever virus exposure in Northern Argentina.

In 2007-2009, a major yellow fever virus (YFV) outbreak in Northern Argentina decimated the local howler monkey (Alouatta) population. To evaluate whether the surviving howler monkeys possess advantageous genetic variants inherited from monkeys alive prior to the YFV outbreak, we explored the relationship between Toll-like receptor (TLR) 7 and TLR8 gene variation and YFV susceptibility. We used samples from Alouatta individuals in Misiones, Argentina alive before the YFV outbreak, individuals that died during the outbreak, and individuals that survived the outbreak and are alive today. We measured genetic divergence between Alouatta YFV exposure groups and evaluated Alouatta-specific substitutions for functional consequences. We did not find different allele frequencies in the post-YFV exposure Alouatta group compared to the pre-exposure group. We identified three nonsynonymous variants in TLR7 in Alouatta guariba clamitans. Two of these substitutions are under positive selection in functionally important regions of the gene. Our results did not indicate that surviving howler monkey spossess advantageous genetic variants at greater frequency than those alive before the YFV outbreak. However, the positively selected unique coding differences in A. guariba clamitans are in the region important in pathogen detection which may affect YFV resistance. Morework is necessary to fully explore this hypothesis.

ACE2 and TMPRSS2 variation in savanna monkeys (Chlorocebus spp.): Potential risk for zoonotic/anthroponotic transmission of SARS-CoV-2 and a potential model for functional studies.

The COVID-19 pandemic, caused by the coronavirus SARS-CoV-2, has devastated health infrastructure around the world. Both ACE2 (an entry receptor) and TMPRSS2 (used by the virus for spike protein priming) are key proteins to SARS-CoV-2 cell entry, enabling progression to COVID-19 in humans. Comparative genomic research into critical ACE2 binding sites, associated with the spike receptor binding domain, has suggested that African and Asian primates may also be susceptible to disease from SARS-CoV-2 infection. Savanna monkeys (Chlorocebus spp.) are a widespread non-human primate with well-established potential as a bi-directional zoonotic/anthroponotic agent due to high levels of human interaction throughout their range in sub-Saharan Africa and the Caribbean. To characterize potential functional variation in savanna monkey ACE2 and TMPRSS2, we inspected recently published genomic data from 245 savanna monkeys, including 163 wild monkeys from Africa and the Caribbean and 82 captive monkeys from the Vervet Research Colony (VRC). We found several missense variants. One missense variant in ACE2 (X:14,077,550; Asp30Gly), common in Ch. sabaeus, causes a change in amino acid residue that has been inferred to reduce binding efficiency of SARS-CoV-2, suggesting potentially reduced susceptibility. The remaining populations appear as susceptible as humans, based on these criteria for receptor usage. All missense variants observed in wild Ch. sabaeus populations are also present in the VRC, along with two splice acceptor variants (at X:14,065,076) not observed in the wild sample that are potentially disruptive to ACE2 function. The presence of these variants in the VRC suggests a promising model for SARS-CoV-2 infection and vaccine and therapy development. In keeping with a One Health approach, characterizing actual susceptibility and potential for bi-directional zoonotic/anthroponotic transfer in savanna monkey populations may be an important consideration for controlling COVID-19 epidemics in communities with frequent human/non-human primate interactions that, in many cases, may have limited health infrastructure.

Distribution and conservation status of Boutourlini's blue monkey (Cercopithecus mitis boutourlinii), a Vulnerable subspecies endemic to western Ethiopia.

Reliable data on the distribution and threats facing primate species are crucial to identifying priority sites for conservation and designing effective management plans. Boutourlini's blue monkey (Cercopithecus mitis boutourlinii) is a little-known arboreal primate endemic to the forests of western Ethiopia. This subspecies is categorized as Vulnerable on the International Union for Conservation of Nature (IUCN) Red List and the distribution of extant populations is largely unknown. To increase our knowledge of the spatial distribution and conservation status of Boutourlini's blue monkey, we carried out intensive reconnaissance surveys from January 2010 to May 2011 across approximately 40% of its potential range and conducted interviews with local people at each of the survey locations. We carried out geospatial analyses and mapped the distribution of Boutourlini's blue monkey localities with respect to elevation, protected area status, and changes in forest cover over time using ArcGIS10.4.0. Through our surveys, we discovered 30 previously unknown Boutourlini's blue monkey populations in three administrative regions of western Ethiopia (Amhara, Oromia, and Southern Nations, Nationalities and People's Regions). A total of 34 different groups were sighted and counted at the survey sites, averaging 14.7 members (range 8-23) per group. There are now 32 Boutourlini's blue monkey populations of recently confirmed occurrence at altitudes ranging from 1039 to 2780m asl, seven in forests of greater than 50km2. Crop feeding by Boutourlini's blue monkeys was reported by people at seven sites and confirmed through direct observation at three of these sites. None of the known extant populations of Boutourlini's blue monkeys occur within a strictly protected area (e.g., national park) where exploitative human activities are outlawed. A complete reassessment of the distribution and conservation status of Boutourlini's blue monkey will require further surveys across the remaining approximately 60% of its potential range.

Synchronization of weaning time with peak fruit availability in squirrel monkeys (Saimiri collinsi) living in Amazonian Brazil

Many mammals coincide their reproductive activities with factors such as ambient temperature, rainfall, and food availability. In primates that invest immediate food intake into reproduction, the periods of maximum fruit production often coincide with the peak of lactation (to maximize maternal survival) or the occurrence of weaning (to maximize infant survival). This study investigates the relationship between reproductive periods and the availability of ripe fruit in the habitat of a population of wild squirrel monkeys (Saimiri collinsi) in Amazonian Brazil. We combine data from several years (2002-2003; 2011-2015) during which we followed the monkeys and quantified the occurrence of matings, gestations, births, and the number of lactating females. We also collected rainfall and plant phenological data for 24 months. Our results confirm that reproductive events are highly seasonal in S. collinsi. The period of weaning corresponded to the peak in the abundance of ripe fruits consumed by the monkeys. This indicates that the period of infant nutritional independence is optimally timed to coincide with periods of greater food production in this habitat. We suggest that seasonal breeding in these primates does not necessarily reduce maternal energetic stress, but likely improves infant survivorship.

Anogenital distance as a measure of male competitive ability in Rwenzori Angolan colobus.

Anogenital distance (AGD) is positively correlated to fetal androgen exposure and developmental masculinization in mammals. Independent of overall body size, AGD shows a strong positive correlation with male fertility and in rodents, AGD is a good indicator of male competitive ability and is associated with female choice. We hypothesized that AGD will also predict male competitive ability in non-human primates. To test this, we measured AGD noninvasively with a parallel laser in a wild population of Angolan colobus monkeys (Colobus angolensis ruwenzorii) in Uganda and correlated to it to their social structure. C. angolensis ruwenzorii form a multilevel society with both one-male/multifemale units (OMUs) and multimale/multifemale units (MMUs). We compared AGD in males from five OMUs and six MMUs and related it to their fecal androgen metabolite concentrations, dominance rank and body size, and to the number of females in their unit. Males in OMUs had greater access to females, so were predicted to have longer AGDs, but this was not found. AGD also did not correlate overall with mean fecal androgen metabolites in MMUs. However, AGD was correlated with dominance rank in MMUs, demonstrating that higher-ranking males in these multimale units had longer AGDs. Body size did not show the same relationship with dominance rank, suggesting that male rank was not just a reflection of absolute male size. Our findings indicate that AGD predicts male competitive ability in this species and that it may be a useful correlate throughout the non-human primates. These results also support the idea that prenatal androgen exposure increases the likelihood of the expression of behaviors that maintain high dominance rank.

Open/close-ended vasectomy technique by single incision on vervet monkeys (Chlorocebus pygerythrus).

Vervet monkeys (Chlorocebus pygerythrus), considered a species of "least concern" by the International Union for Conservation of Nature (IUCN), are widely maintained at primate sanctuaries in South Africa. Permanent surgical contraception is a necessary method for the management of this species in captivity. In this study, a new vasectomy technique was evaluated and involves a prescrotal approach with only one surgical incision, aiming to excise a piece of vas deferens, leaving open the testicular side, and creating a loop on the prostatic side to avoid future recanalization. The birth rate was studied to assess the success of the technique. This technique significantly reduced breeding in the study population from 33 births in the first year to four births during the last year of the study. These results show that this type of vasectomy is a fast, simple, and safe technique for controlling monkey populations in sanctuaries.

Responses to Spatial and Temporal Variation in Food Availability on the Feeding Ecology of Proboscis Monkeys (Nasalis larvatus) in West Kalimantan, Indonesia

Folivorous primates have long been assumed to experience food competition less acutely than frugivores due to their ability to eat leaves, an abundant resource in most forest systems. Consequently, the behavioural responses of leaf-eating primates to variation in food availability are less well characterised than those of frugivores. Recent empirical studies have demonstrated that many colobine species are more affected by food availability and distribution than previously thought; they employ multiple strategies to survive during periods of food scarcity. We studied a population of proboscis monkeys (Nasalis larvatus) over 16 months in three forest types in West Kalimantan, Indonesia, to examine their responses to temporal fluctuation and spatial variation in food availability. We examined how feeding behaviour was influenced by the availability of plants in botanical plots to identify important and preferred foods of proboscis monkeys across months and in different forest types. Proboscis monkeys consumed foods from 68 genera, comprising 35% young leaves, 27% unripe fruit, 12% flowers and 6% mature leaves. Consumption of plant parts and genera by proboscis monkeys varied in response to monthly changes in food availability but did not vary among forest types despite substantial differences in phenology and floristics among them. The monkeys preferred unripe fruits and flowers and used young and mature leaves as fallback foods in mangrove forests. Documentation of proboscis monkey responses to variation in food availability contributes to our understanding of how monkeys respond to changes in their environments due to climate change and habitat degradation.

PENDUGAAN POPULASI BEKANTAN (Nasalis larvatus) DI TAMAN WISATA ALAM TANJUNG BELIMBING KECAMATAN PALOH KABUPATEN SAMBAS

Proboscis monkey (Nasalis larvatus) is an endemic animal of Borneo including protected primate species as an endangered species status. This species listed as an endangered species caused by large population decline and habitat demage continues to threaten the proboscis population. This research was conducted in Taman Wisata Alam Tanjung Belimbing (TWATB) is a nature conservation area that supports the conservation of proboscis monkey. The purpose of this research is to collect the amount of proboscis monkey populations, so as to provide an overview of conservation efforts that must be carried out. The method was used the River Survey method. The result of Proboscis research based on the age level was found consisted average of 5 adult male individuals, 6 adult female individuals, 7 adolescent individuals and 5 childs. Estimation of the population is calculated using the King’s Method. Estimated individuals population is 12 individuals with a density of 25.5 individuals/km2.Keywords: Proboscis monkey, Population, Tanjung Belimbing, Paloh.

Sexual dimorphism in the loud calls of Azara's owl monkeys (Aotus azarae): evidence of sexual selection?

Primates use different types of vocalizations in a variety of contexts. Some of the most studied types have been the long distance or loud calls. These vocalizations have been associated with mate defense, mate attraction, and resource defense, and it is plausible that sexual selection has played an important role in their evolution. Focusing on identified individuals of known sex and age, we evaluated the sexual dimorphism in a type of loud calls (hoots) in a population of wild owl monkeys (Aotus azarae) in Argentina. We found evidence of sexual dimorphism in call structure, with females and males only emitting one type of call, each differing in dominant frequency and Shannon entropy. In addition, both age-related and sex-specific differences in call usage were also apparent in response to the removal of one group member. Future acoustic data will allow us to assess if there are individual characteristics and if the structure of hoot calls presents differences in relation to the social condition of owl monkeys or specific sex responses to variants of hoot calls' traits. This will provide deeper insights into the evolution of vocal mechanisms regulating pair bonding and mate choice strategies in this and other primate species.

Fruit production needed to maintain populations of woolly monkeys: Recommendations for reintroduction projects

Woolly monkeys are threatened and reintroduction projects are an alternative for their conservation. However, there is little quantitative information suggesting the habitat traits needed to sustain populations. In this study, we first analyze the factors determining the abundance of woolly monkeys (Lagothrix spp.) and second, we suggest the minimum amount of fruit production able to maintain a population. Data was obtained from a literature review including 50 Neotropical sites, and we added new information from three more sites recently gathered in Colombian forests. We used simple and logistic regression models on two scales: large (i.e. all Neotropical sites), and medium (i.e. sites within their geographic range). On the large spatial scale, the abundance of woolly monkeys was positively related with annual rainfall, and plant species richness; and negatively associated with the number of dry months. On medium scales, we found that the most important variables explaining the abundance of woolly monkeys across scales was fruit production. The regression models suggest that at least 200–300 kg/ha.yr are necessary to support a population of woolly monkeys, and according to a logistic regression 400 kg/ha.yr are needed so surpass the 0.5 chance to have a population. In reintroduction projects, since it is difficult for new occupants to efficiently use the natural resources, we suggest that this amount of fruit should be aimed. As fruit production seems to be associated with high soil fertility (e.g. close to the Andean mountains), this region should be priority for conservation projects on this species.

Genetic diversity of the Sichuan snub-nosed monkey (Rhinopithecus roxellana) in Shennongjia National Park, China using RAD-seq analyses.

The Sichuan snub-nosed monkey (Rhinopithecus roxellana) is an endangered species endemic to China, where the smallest population resides in Shennongjia National Park, Hubei Province. In this study, the genetic diversity of the Sichuan snub-nosed monkeys from two areas, Qianjiaping (QJP) and Dalongtan (DLT) in Shennongjia National Park was evaluated using single nucleotide polymorphisms (SNPs) data derived from restriction site-associated DNA sequencing (RAD-seq). A total of 41,260 SNP loci were found in 29 Sichuan snub-nosed monkey individuals. The genome-wide nucleotide diversity (π) of the Shennongjia population was 0.001842. The genetic differentiation (FST) between the QJP and DLT subpopulations was 0.034. The heterozygosity of individuals from QJP was 0.3475 ± 0.03696 and 0.3148 ± 0.03501 for individuals from DLT. Although the DLT and QJP subpopulations did not show significant genetic differences, genetic differentiation between the two subpopulations was confirmed using Bayesian cluster analysis, neighbor-joining trees and principal component analysis. These results suggest that the Shennongjia population of Sichuan snub-nosed monkey has relatively low genetic diversity at the genomic level. The little genetic differentiation noted between the DLT and QJP subpopulations likely due to natural and anthropogenic barriers which may exacerbate loss of genetic diversity of this endangered subpopulation.

The tonkin snub-nosed monkey <i> Rhinopithecus avunculus </i> population in the Quan Ba forest, north-east Vietnam: an identification of priority habitat for conservation

The Tonkin Snub-nosed Monkey Rhinopithecus avunculus is among the World’s 25 most endangered primates. At present, the species is found only in few forest areas in Ha Giang and Tuyen Quang Provinces, north-east Vietnam with a total number not exceeding 250 individuals. The forest block in Cao Ma Po, Ta Van and Tung Vai Communes of Quan Ba District, Ha Giang Province (the Cao - Ta - Tung forest) harbors the second largest population of Tonkin Snub-nosed Monkey. This population was estimated to be conisted of about 30–35 individuals in 2007. However, it faces a number of serious threats (wildlife hunting, habitat degradation by widespread forest farming of Tsao-ko cardamom plant, etc.) that may lead the population to be extinct in near future. The population was reduced to 15–21 individuals in 2016 due to these threats. In 2017–2018, we conducted a study to identify a priority habitat area to establish the Quan Ba Tonkin Snub-nosed Monkey Conservation Area. The results of our study show that the distribution of the Quan Ba Tonkin Snub-nosed Monkey population is confined to a small area (about 5,000 ha) belonging to the Theng Chu Phin, Dao Dan Chai, Ta Lay mountains, the Hill 754 and a forest patch along the Vietnam-China border from the Post 283 to Post 295. This area harbors the best forest of the Cao - Ta - Tung area. The forest covers 92.3% of the area, and only 7.7% of the area is a non-forest land. There are two types of forest: evergreen broad-leaved forest (50.0% of total area) and limestone evergreen broad-leaved forest (42.3%). The evergreen broad-leaved forest has been degraded to medium and restoration status. Tsao-ko cardamom Amomum tsao-ko fields are widespread. The limestone evergreen broad-leaved forest of almost primary status remains in very steep slopes and limestone mountains. The Cao - Ta - Tung forest was designated as a watershed protection forest that allows farming of agricultural and medicinal plants inside the forest and the forest farming of Tsao-ko cardamom is widespread becoming the most serious threat to the long-term survival of the Tonkin Snub-nosed Monkey population. In order to ensure long-term survival of the Quan Ba Tonkin Snub-nosed Monkey population, the area of the Theng Chu Pin, Dao Dai Chai, Ta Lay, Tung Lau mountains, the Hill 754 and a forest patch along the Vietnam-China border from the Post 283 to Post 285 must be designated as a special-use forest, i.e. to establish a Quan Ba Tonkin Snub-nosed Monkey Conservation Area.