Search

The Annamites ecoregion harbors exceptional levels of species richness and endemism, but intensive snaring has decimated populations of terrestrial mammals. Ungulates, such as muntjacs, are susceptible to snaring, and in need of effective conservation action. At least three muntjacs occur sympatrically in the region: the Annamite dark muntjac species complex Muntiacus rooseveltorum/truongsonensis, the northern red muntjac Muntiacus vaginalis, and the large-antlered muntjac Muntiacus vuquangensis. We conducted a landscape-scale systematic camera-trapping survey in Nakai-Nam Theun National Park to gather information on the ecology and distribution of these muntjacs. We analyzed camera-trap records within an occupancy framework to evaluate responses to environmental and anthropogenic variables, and to predict distributions across the protected area. We found varying responses to the covariates, indicating complex drivers of occurrence, though all three muntjac had higher occupancies in more inaccessible areas. Mean (95%) PAO in the protected area was higher for large-antlered muntjac (0.33 [0.22–0.49]), followed by Annamite dark muntjac (0.28 [0.18–0.39]), and then northern red muntjac (0.27 [0.15–0.42]). Large-antlered muntjac and northern red muntjac were widespread, while dark muntjac was restricted to a single high elevation area. Overall, our results provide new insights into muntjac ecology, distribution, and population status, and we discuss how this information can be used to inform conservation efforts. Given the high occupancies that we found for the Critically Endangered large-antlered muntjac, we argue that Nakai-Nam Theun National Park may be vital for the long-term survival of the species.

Species distribution models are a key component for understanding a species’ potential occurrence, specifically in vastly undersampled landscapes. The current species distribution data for the Assamese macaque Macaca assamensis are outdated, but suggest a patchy distribution in moist broadleaved forests in South and Southeast Asia. Therefore, in this study, we used a species distribution model to explore the potential climatic niche of this species and assess its distribution and potential barriers in 12 South and Southeast Asian countries. We combined primary and secondary species occurrence records from different countries. We applied Classification and Regression Tree (CART), TreeNet (boosting), RandomForest (bagging) and Maximum Entropy (MaxEnt) machine-learning algorithms with elevation as well as 19 bioclimatic variables for the first ensemble predictions ever completed for this species. Our results suggested that the predicted distribution of the Assamese macaque is strongly associated with precipitation of warmest quarter (BIO18), temperature annual range (BIO7) and temperature seasonality (BIO4). Our prediction shows a continuous potential climatic niche of the species from east of the Kaligandaki River in Nepal to Lao People’s Democratic Republic. There are also potential niche patches in Bhutan, Southeast China, Thailand and Cambodia, while Pakistan and Afghanistan have no potential niche for the species. We believe that our workflow presents a new conservation-oriented open access research template to progress empirical primate conservation worldwide.

Studying the structure and patterns of vocalizations in primates is important to understand their evolution, responses to changing environments, and social behavior, and to design efficient vocalization-based survey techniques. Gibbons (Hylobatidae) are small arboreal apes known for their stereotyped songs. Data on their vocalization patterns remain limited, especially for crested gibbons (Nomascus spp.). We recorded songs of white-cheeked gibbons (Nomascus sp.) heard from listening posts at a site in Nakai–Nam Theun National Protected Area, central-eastern Laos, during a cold dry and a warm dry season, from November 2013 to May 2014, along with weather data. Males typically initiated the duet songs at a mean time of 06:14 h. Duet song bouts lasted a mean of 16 min. Song bout length was relatively constant throughout the study but decreased with the occurrence of wind. On a given day, the first male song started at a mean of 12 min before sunrise and all songs ceased at a mean of 13 min after sunrise. The start time of the first song relative to sunrise did not differ significantly between the two seasons but we found a significant negative relationship between the start time of the first song and both time of sunrise and temperature. The mean number of song bouts heard was significantly larger during the cold dry season than the warm dry season, and we found a significant negative relationship between the number of song bouts heard and temperature. Song rates also increased during days with no rain relative to rainy days. Our findings provide a preliminary understanding of song patterns in Nomascus spp. and can aid the planning and interpretation of surveys that rely on documenting their calls.

The Javan slow loris Nycticebus javanicus is threatened by habitat decline and is classified as Critically Endangered on the IUCN Red List. Information on its distribution and habi- tat preferences is still lacking, and so far the distribution of the Javan slow loris has only been quantified via ecological niche modelling based on museum specimens and remotely derived environmental layers. We aimed to refine the modelled predictions and to verify the distribution of the Javan slow loris by collecting up-to-date occurrence data, which are fundamental for con- servation and management of the species. Furthermore, we identify variables that predict its pres- ence and give recommendations for future survey sites and conservation actions. From April to June 2012 we collected data on species presence, habitat preferences and levels of disturbance at priority sites throughout Java. We present a map of the predicted distribution of N. javanicus based on a maximum entropy model. We investigated habitat preferences using R (v. 2.14.1). Dur- ing the study we sighted 52 lorises in 9 out of 14 investigated areas. The amount of bamboo in a forest had a positive effect on the encounter rates. Furthermore, we made 86% of sightings in for- est plantations and agricultural areas located outside protected areas, with the majority located in areas with measured high levels of disturbance. We suggest that further ecological studies are needed to understand if and why densities may be higher in anthropogenically disturbed areas.

The Endangered red-shanked doucPygathrix nemaeusis a charismatic Asian colobine endemic to Vietnam, Cambodia and Lao People's Democratic Republic (PDR). The largest population is found in central-eastern Lao PDR but it has never been quantified. We conducted line-transect surveys in Nakai–Nam Theun National Protected Area in 2011–2012. We used distance sampling combined with a habitat suitability model to estimate group density and group abundance in the area. Our analysis yielded a density of 2.8 (range 1.9–4.1) groups per km2and c. 4,420 groups within the predicted c. 1,600 km2of suitable habitat in Nakai–Nam Theun. These are the only available data forP. nemaeusin Lao PDR to date. We discuss the limitations of our survey, which involved potential violations of the distance sampling method, and highlight the challenges of using this method for primates. We also consider the importance of assessing limitations in distance sampling studies, to evaluate reliability and facilitate comparisons. The population ofP. nemaeusin Lao PDR is under threat from illegal hunting and is not the focus of any specific conservation action. To avoid a repetition of the decline the species has already experienced in Vietnam, and to secure the species' global survival, conservation projects need to target the population in Nakai–Nam Theun. A long-term conservation and research project in this key biodiversity area will also benefit other threatened and unique co-existing species.

The endangered red-shanked douc (Pygathrix nemaeus), endemic to Lao PDR, Vietnam, and perhaps Cambodia, remains little known. The Lao population is highly threatened. To improve conservation prospects of the species there, we here update a status review from 1999. Subsequent literature (mostly not readily available to the outside scientific community) was reviewed critically. Doucs and their habitat in Lao PDR faced continuous, increasing threats in the past 10 years through large development projects and heavy hunting. Many locations with records from the 1990s were not surveyed in the last decade, so douc persistence remains uncertain in them. Given the poor status of the species in Vietnam and Cambodia, the Lao population is surely the world's largest and the best hope for the species' global conservation. Resources for conserving species are very limited in the country, urging prioritization of populations, so available resources have maximum effect. Nakai-Nam Theun and Hin Namno National Protected Areas hold the largest populations of P. nemaeus, but face great threats from hunting. Management of these areas (and secondary priority areas) should focus on control of this illegal activity.

We conducted a primate survey in Samkos Wildlife Sanctuary, western Cambodia, during the wet season in 2009. We visually confirmed the presence of five out of six primate species thought to occur in the area: Bengal slow loris Nycticebus bengalensis, Indochinese silvered langur Trachypithecus germaini, pileated gibbon Hylobates pileatus, pig-tailed macaque Macaca leonina and long-tailed macaque Macaca fascicularis. We did not find any sign of the stump-tailed macaque Macaca arctoides and suggest it is absent in Samkos Wildlife Sanctuary and possibly from the Cardamom Mountains. We provide the abundance measures for each primate species; the three most abundant species were Bengal slow loris, Indochinese silvered langur and pileated gibbon. We propose Samkos Wildlife Sanctuary as a priority for primate conservation in Cambodia.

The endangered red-shanked douc (Pygathrix nemaeus), endemic to Lao PDR, Vietnam, and perhaps Cambodia, remains little known. The Lao population is highly threatened. To improve conservation prospects of the species there, we here update a status review from 1999. Subsequent literature (mostly not readily available to the outside scientific community) was reviewed critically. Doucs and their habitat in Lao PDR faced continuous, increasing threats in the past 10 years through large development projects and heavy hunting. Many locations with records from the 1990s were not surveyed in the last decade, so douc persistence remains uncertain in them. Given the poor status of the species in Vietnam and Cambodia, the Lao population is surely the world's largest and the best hope for the species' global conservation. Resources for conserving species are very limited in the country, urging prioritization of populations, so available resources have maximum effect. Nakai-Nam Theun and Hin Namno National Protected Areas hold the largest populations of P. nemaeus, but face great threats from hunting. Management of these areas (and secondary priority areas) should focus on control of this illegal activity.