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Reintroduction of the 'Critically Endangered' Delacour's langur (Trachypithecus delacoufl) into Van Long Nature Reserve, Ninh Binh Province, Vietnam
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... The reintroduction process was never completed but the individuals developed a small population in the semi-wild area. Between 2011 and 2012, the center successfully released five individuals of T. delacouri into the wild (Nadler 2013;Elser et al. 2015). Zoo Ostrava financially supports the conservation of T. delacouri in the Van Long Reserve in the Ninh Binh province located in North Vietnam (Zoo Ostrava 2024a). ...
... Each outer coordinate is combined to form one polygon which represents the home range of an orang-utan at a certain time. Determining the horizontal area uses the Maximum Convex Polygon method (14). The interaction and use of food trees and sleeping trees by orangutans and other primates uses the scan sampling method, by observing and recording orangutans at certain time intervals and recording all activities carried out by orangutans in the ethogram that has been prepared. ...
Orangutans are a wild animal species that is threatened with extinction, so the IUCN has designated its conservation status as Critical Endangered and Appendix I in CITES. The Indonesian government has also designated the Sumatran orangutan as a protected animal. Jantho Nature Reserve (JNR) is one of the conservation areas that is used as a place for orangutan reintroduction. This area is also an important habitat for seven other primate animals. On the other hand, reintroduced orangutans are arboreal animals that have become accustomed to the human environment. They do not know the types of trees that source their food, and the predators that endanger them. This will be a threat to the sustainability of reintroduced orangutans in the area. This research is important to carry out because there is still very little information regarding the use of vertical space in the daily movements of reintroduced orangutans, and there is no information about the daily movements of reintroduced orangutans in the JNR area. This research aims to obtain initial data on the daily movement patterns of reintroduced orangutans in utilizing vertical space to obtain food sources. The transect route is a method used to obtain data on the movement of reintroduced orangutans. A total of 5 line transects were used to collect data by following the reintroduced orangutans and recording each canopy height used by the orangutans for activities. The data obtained was made in tabulated form and analyzed descriptively. The research results showed that reintroduced orangutans used vertical space at a height of 1 – 29 m. This height level was different for the four reintroduced orangutans observed. molikha has higher activity at a height of 1 – 10 m. Poni activity is highest at a height of 10 – 19 m. Cut keke and asokha use higher vertical space at a height of 20 -30 m. A total of 34 trees were used as reintroduced orangutans as activity sites, with tree heights of 1 – 30 m and trunk diameters of 1 – 200 cm. Vegetation connectivity is still connected between vegetation.
... Setiap koordinat terluar digabungkan membentuk satu poligon yang merupakan daerah jelajah suatu kelompok pada kurun waktu tertentu. Penentuan luas daerah jelajah Kedih menggunakan metode Maximum Convex Poligon (Elser et al. 2015). Interaksi dan pemanfaatan pohon pakan dan pohon tidur menggunakan metode scan sampling, dengan mengamati dan mencatat kelompok pada interval waktu tertentu dan mencatat seluruh kegiatan yang dilakukan kelompok dalam ethogram yang telah disusun. ...
Thomas langur (Presbytis thomasi) is an endemic primate to Aceh and North Sumatra. These primates have a local name, “Kedih.” Forest fires and forest functions conversion into oil palm plantations are pressure on their habitat and have decreased wild populations in nature. As arboreal animals, their movements depend heavily on the connectivity of vegetation. Comprehensive research is needed to obtain horizontal and vertical daily movement data of the thomas langur. This study used GPS to take coordinates, a camera to document Thomas langur and its food trees, and Thomas langur as a research object. The data recorded includes the coordinates of each forage tree, the type of forage tree, and the height of the canopy strata used by Thomas langur for foraging. The hardwood movement data was plotted on ArGis 10.1 to get the horizontal hardness movement area. Tree height data was obtained by measuring the tree height where Thomas langur stopped to look for food. Kedih movements to look for food are carried out daily from morning to evening. The results showed that the short length of movement was highly depend on the availability of forage trees. The denser the forage trees, the shorter the daily activities of Thomas langur. This daily movement can be done horizontally and vertically. Horizontally, Thomas langur moved to follow the forage trees, and vertically, Thomas langur moved by utilizing the height of the forage trees. Horizontally, Thomas langur moved 144.92 m in the rehabilitation block and 62.30 m in the protection block. The Thomas langur home ranged in the rehabilitation block is 27 ha, and 25 ha in the protected block. Vertically, Kedih in the rehabilitation blocks and protected blocks moved to trees with a height of 11-20 m, as much as 49%.
... Reduced available habitat for the species may also cause long-term issues, such as inbreeding or increased intra-population competition. Consequently, there have been several programs aimed at reintroducing Delacour's langur individuals to promising sites, including the western portion of Van Long in 2011 and 2012 (Nadler, 2012;Elser et al., 2015), and Trang An in 2020 (Nadler et al., 2020b). Hence, identifying potential sites for similar initiatives in the future is important. ...
The Delacour's langur (Trachypithecus delacouri) is a critically endangered and endemic primate that inhabits a small region in North Vietnam. While the main threats to the langurs include illegal hunting and habitat destruction, the potential impacts of climate change on this species have never been assessed. In this study, we used Maxent, a species distribution modelling approach that has been shown to be suited for rare species, to assess the effects of climate change on the distribution of the Delacour's langur in different future scenarios. We constructed an optimally tuned model to predict climatically suitable habitat for T. delacouri in current conditions, then projected the models to three future periods, 2041-2060, 2061-2080, and 2081-2100 using data from three general circulation models. Our models showed high predictive performance and successfully predicted the current known range, but also showed areas of overprediction that may reflect a part of the langur's ecology. Our results estimated an overall loss in total suitable habitat, with an average value of approximately-26.97% in the 2041-2060 period,-29.81% in the 2061-2080 period, and-15.48% in the 2081-2100 period, compared to the current predicted range, but they also predicted the currently important Van Long-Kim Bang region as suitable across all future scenarios. We suggest that some of the predicted climatically suitable areas, including Van Long, Kim Bang, Lac Thuy, and Cuc Phuong, may be crucial for future conservation and population re-establishment/re-introduction activities of the Delacour's langur.
... Special protection against the effects of habitat destruction and poaching that the Vietnam Primate Conservation Program has been able to afford this species in the Van Long Nature Reserve has had a significant impact on population numbers there. With the help of two pilot projects (in 2011 and 2012) to augment the existing population through the release of captive born individuals, this has led to an increase from c.50 individuals to a secure count of 176-184 individuals (Agmen, 2014;Elser 2013;Elser et al. 2015;Nadler 2012;Nguyen Van Linh et al. 2019). The next largest surviving sub-population, of about 80 individuals, exists in neighbouring Ha Nam Province, in a currently unprotected area (Kim Bang). ...
At the present time, the Van Long Nature Reserve Ninh Binh Province is home to the only viable sub-population of the ‘Critically Endangered’ Delacour’s langur (Trachypithecus delacouri). The reserve contains about 200 individuals. The next largest sub-population of about 80 individuals exists in neighboring Ha Nam Province, in a currently unprotected area. Such small and isolated populations have heightened vulnerability to internal and external threats to their survival. The establishment of further sub-populations in suitable, secure and sustainable locations, therefore, is a crucial step towards helping to safeguard the survival of this species. Until the late 1990’s a small population is known to have existed in the Trang An limestone massif, Ninh Binh Province. In 2014 Trang An was inscribed as UNESCO World Heritage Site. With strict protection of the area now in place and the existing and excellent habitat that the massif offers for Delacour’s langurs, the establishment of a new sub-population here was recommended soon after its inscription and is included in the “Urgent Action Plan for the Conservation of Primates in Vietnam until 2020, Vision 2030”. The Endangered Primate Rescue Center (EPRC), located in Cuc Phuong National Park, started breeding programs for several species of highly endangered primates in 1993, with the goal of releasing captive born individuals to support depleted wild populations or to establish new populations where the species has been extirpated. In 2017 a collaborative venture between local, national and international stakeholders was initiated to set in motion a reintroduction program for Delacour’s langurs in Trang An. In August 2020, a group of three captive-born Delacour’s langurs was transferred to an island in the World Heritage Site as a first step towards a possible re-establishment of a sub-population in this area.
The Colobines are a group of Afroeurasian monkeys that exhibit extraordinary behavioural and ecological diversity. With long tails and diverse colourations, they are medium-sized primates, mostly arboreal, that are found in many different habitats, from rain forests and mountain forests to mangroves and savannah. Over the last two decades, our understanding of this group of primates has increased dramatically. This volume presents a comprehensive overview of the current research on colobine populations, including the range of biological, ecological, behavioural and societal traits they exhibit. It highlights areas where our knowledge is still lacking, and outlines the current conservation status of colobine populations, exploring the threats to their survival. Bringing together international experts, this volume will aid future conservation efforts and encourage further empirical studies. It will be of interest to researchers and graduate students in primatology, biological anthropology and conservation science. Additional online resources can be found at www.cambridge.org/colobines.
During2019 and2020, 14areasin Northern Vietnamweresurveyedfor Delacour’s langur Trachypithecus delacouri(Osgood, 1932) to confirm the status of distribution,estimated populations and intensityof hunting pressure.People from elected local authorities, as well as otherindividuals,wereinterviewed to determine their awareness of the langur’s conservation. These data werecombined for statistical analysis. The results showed that protectionstatus was negatively correlated with hunting pressure (Rs= -0.601;p = 0.006). Hunting pressure also had anegative relationship with the growth of the number of langur populations (Rs= -0.616; p = 0.005) and the number of langur individuals (Rs= -0.578; p = 0.01). However,placing an area under State protection had no correlation with the growth of the population of Delacour's langur living there(p > 0.05). People's awareness in Van Long Nature Reserve was very high (over 99% strongly supportedthe conservation of Delacour’slangur)which correspondedto the growth of Delacour's langur population in that area. To protect both the langurs and people's livelihoods, we, therefore,recommend turning the areas where Delacour's langursare distributed into protected areasand also promoting people’s awareness through legal dissemination and activities. The reintroductionof the species into suitable protected habitatsshould be carried out scientifically.
The use of GPS telemetry has been a reliable research tool for the study of primate biology in recent years. Although in the past technological restrictions limited its use mainly to large primates, recent improvements in battery size make it possible to use this technology for small species. We used GPS devices for monitoring two adult white-footed tamarins (Saguinus leucopus) from a free-ranging group, and assessed its applicability for recording spatial and ecological data. GPS devices were operational for 66 and 85 days, recording 221 positions (36.6% acquisition rate; 73% of which were highly accurate) and 3195 activity values for both individuals. Depending on the estimation method, we calculated the home range size for the group to be 19.4 and 22.9 ha, which were within the range for the species in other localities. The animals were active each day for 11 h, with high activity during the early morning. The monkeys showed a constant and alternate use of four sleeping sites with a limited reuse of the same site on consecutive nights. These daily activity and sleeping site use patterns are similar to those reported for other Saguinus species. Based on the kind and quality of the data recorded, we consider GPS telemetry to be an efficient and advantageous method for tracking and obtaining ecological information from S. leucopus. In comparison to other data collection methods, GPS telemetry required fewer personnel and less time commitment to record data without compromising the accuracy of the spatial and activity information we obtained.
Primate home range size and habitat use are affected by resource availability, which may change seasonally. Limestone langurs (Trachypithecus genus), including the Critically Endangered Cat Ba langur (Trachypithecus poliocephalus), live on limestone karst hills with shrubby and discontinuous vegetation. This study explores home range size and habitat use in relation to substrate, vegetation coverage, and hill type for Cat Ba langurs living on Cat Ba Island. We predicted that home range size would be similar to that of other limestone langurs and that as resources vary seasonally and across habitat types, habitat use would vary with season and behavior, with foraging concentrated on slopes, where food is plentiful. We collected 180 days of observational data on two reproductive groups (N = 7 and N = 10–13), taking GPS fixes of the group whenever they moved farther than the typical group spread to determine home ranges, and 10-min instantaneous scans to assess habitat use. The two groups had home ranges of 22 ha and 50 ha (0.32 and 0.20–0.26 individuals/ha respectively). Ranges for both groups were smaller in the dry season than the wet season, although we could not assess seasonal variation statistically. The langurs spent most scans on rocks, in sparsely vegetated areas, and on exposed slopes and steep cliffs; however they foraged primarily on gradually inclined slopes, especially in the dry season. These results suggest that conservation efforts should focus on protecting nutritionally important valleys and exposed slopes to ensure year-long access to food resources. It may, however, be difficult to balance human and nonhuman primate habitat use.
Home-range size is widely used in wildlife biology to assess animal-habitat relationships. But home-range size estimation largely depends on the estimator and sample size used. Using 3 different estimators (minimum convex polygons, fixed-kernels, clusters), we used data collected on moose (Alces alces), fitted with Global Positioning System (GPS) collars (which allow automatic recording of large data sets with fewer field constraints than VHF telemetry) to investigate to what extent increasing the number of locations affects home-range size estimations. Our results indicated that 100 to 300 locations per animal annually and 30 to 100 locations seasonally were needed to reach an asymptote. High biases occurred below this asymptotic value. Minimum convex polygons consistently underestimated home-range sizes, but fixed-kernel and cluster estimators followed variable trends that often overestimated home-range sizes. Low sampling efforts also affected the number of animals needed to ensure an adequate statistical power of analysis to compare space use between 2 groups. Despite the higher cost, our findings indicate that in most instances, GPS telemetry is better suited than conventional radiotelemetry to estimate home-range sizes precisely and accurately. Moreover, this tracking technique is not limited by meteorological constraints and allows for the collection of similar sample sizes for all tracked animals, which is of major importance for further comparisons of space use among individuals.
Van Long Wetland Nature Reserve
- Do Van Cac
Do Van cac. Phi Bao Khanh, Pham Van Dung, Bul Trung Kien (2010): Van Long Wetland Nature Reserve.
Teecommunication Department Ninh Binh.
A survey to evaluate public opinion about the reintroduction of the 'Critically --= Delacour's langur (Trachypithecus delacourt) in Van Long Nature Reserve
- Chung Hong
~ Hong Chung (2013): A survey to evaluate public opinion about the reintroduction of the 'Critically
--= Delacour's langur (Trachypithecus delacourt) in Van Long Nature Reserve, Ninh Binh Province, Vietnam.
-_ = J Primatol. (2(2), 27-35.