Pongo Tapanuliensis Research Articles

Pongo's ecological diversity from dental macrowear analysis

AbstractObjectivesOrangutans are found in tropical rainforests of Borneo (Pongo pygmaeus) and Sumatra (Pongo abelii and Pongo tapanuliensis), and they are primarily considered frugivorous species. However, ecological studies reported differences in feeding behavior between these species. P. pygmaeus spend more time feeding on low‐quality foods, such as bark and tough vegetation than do P. abelii. The aim of this study is to investigate if there is any geographic variation in molar macrowear pattern between the two species.MethodsWe analyzed the macrowear pattern of second mandibular molars of 58 orangutan specimens combining dental topographic measurements (occlusal relief index, percentage of dentine exposure, and percentage of enamel wear) with the occlusal fingerprint analysis method.ResultsThe molar macrowear patterns of P. abelii and P. pygmaeus show no significant differences in most of the variables examined in this study. While P. pygmaeus molars are generally characterized by flatter occlusal morphology with slightly larger crushing and grinding areas than those of P. abelii, these differences are not statistically significant. However, we do observe a more variable wear in P. pygmaeus.ConclusionsSimilarities in molar macrowear patterns between the two species could be linked to overlapping long‐term diets, primarily composed of ripe and pulpy fruits. Dental macrowear is a cumulative process that occurs during the individual's lifetime, and it may be difficult to detect seasonal changes through its examination. Future studies could integrate tooth micro‐ and macrowear data for a better understanding of primate dental ecology.

Food diversity of the Tapanuli Orangutan (Pongo tapanuliensis) in the Tapanuli Orangutan Research Station Plan, North Sumatra, Indonesia

The Tapanuli orangutan (Pongo tapanuliensis) is found only in the Tapanuli area. This species includes protected and endangered animals and has a very limited distribution. An important component of animal management is feed availability. This study aims to assess the diversity of food in the Tapanuli orangutan at the Tapanuli Research Station Plan, Batu Satail, Sipirok District. Research was carried out in November 2021 by conducting a vegetation analysis on 3 predetermined paths. The results showed that in this area, there were 91 plant species from 42 families, of which 29 species (31.87%) were orangutan food. However, the highest plant importance index value is dominated by nonfood plants.

Biophysical and anthropogenic factors affecting human and Tapanuli orangutan (Pongo tapanuliensis) conflict in Sumatran tropical rain forest, Indonesia

Abstract Tapanuli orangutan (Pongo tapanuliensis) is a critically endangered species that must be conserved. One of the locations where it is found is Dolok Sipirok Natural Reserve. The threat to this species arises from land use of agriculture and accessibility to the area, resulting in human-orangutan conflict. Identification of conflict areas is necessary. Information on the contributing factors to conflicts between humans and orangutans is also important. This research analyzed the relationship between spatial characteristics with conflict location. The factors including distance to the forest boundary, road, and the river, slope, altitude, and land cover were analyzed. Statistical analysis was performed using Rank Spearman correlation coefficient was. The results showed that distance to farmland and altitude were the main factors affecting the conflict, while the weakest factor was distance from the road. Arse Nauli village was the place where most conflicts occurred. The most robust relationship with conflict was altitude.

Analysis of the Tapanuli orangutan (Pongo tapanuliensis) population in other land use areas, Arse sub-district, South Tapanuli Regency

Tapanuli Orangutan (Pongo tapanuliensis) is a globally critical species (critically endangered) due to the decreasing area of natural habitat. Orangutans can reach out of their natural habitat outside the forest and into community fields for feeding. Orangutans make the other land use not only a place to stopover but also a home range and living area marked by nests. The study aims to obtain information on the characteristics of nests and the estimated population of the Tapanuli orangutan (TO) in the other land-use area. This research method uses line transects placed by systematic sampling with a distance between lines of 3 km and population data analysis using calculations from the van Schaik formula. From the results of the 11 research lines, 14 nests were obtained consisting of 3 class B nests, 5 class C nests, 3 class D nests, and 3 class E nests. The characteristics of the most dominant nests were class C with the most preferred positions II and III and nest finding highest in Quercus maingayi tree. The research found that the density of the TO was eight individuals/1000 ha.

Forest Stand Composition of the Tapanuli Orangutan (Pongo tapanuliensis) Habitat in the Nature Reserves

The Forest areas of Dolok Sipirok Nature Reserve (DSNR) and Dolok Sibual-Buali Nature Reserve (DBNR) are part of Batang Toru forest landscape which is also the habitat of some protected and endangered wildlife such as Tapanuli orangutans (Pongo tapanuliensis). However, the forest has continued to experience widespread pressure and degradation or reduction, mainly due to forest conversion. Therefore, it is very notable to assess the composition of forest vegetation of DSNR and DBNR considering their very important role for the survival of the Tapanuli orangutan populations. The composition of forest vegetation in this research is known by vegetation analysis. The method vegetation analysis used is line transect. The length of the line transect is 1000 m which consists of 10 plots of each transect with a distance between plots of 100 m. Measurements are carried out on the growth rate of seedlings, saplings, poles and trees. Furthermore, the processing of vegetation analysis data is carried out to find out the Important Value Index (IVI), diversity index (H’), evenness (E) and richness (d) of vegetation species in the research area. The results showed that the composition of orangutan habitat vegetation in DSNR consisted of 107 species from 39 families, while DBNR forest consisted of 117 species from 45 families. Tree Syzygium sp1. species consistently have the highest IVI scores at all forest vegetation growth rates of both reserves. The diversity, evenness and richness of DBNR forest vegetation species tends to be higher than DSNR forest.

Assessing the local farmer’s perspective on Tapanuli Orangutan in Agroforest Landscape of Batang Toru Ecosystem, Indonesia

Crop raiding by great apes presents a challenge to conservation due to enhancing human and wildlife conflict, and it is one of the main threats to the existence of newly identified species of Tapanuli Orangutan (Pongo Tapanuliensis). Our study aims to understand communities’ socioeconomics, farmers’ knowledge, perception, attitude, action against Tapanuli Orangutan. Nearly 33% of our respondents showed negative action against Tapanuli Orangutan. Farmer’s claimed that they drive the Orangutan out of their agroforests using tools such as air rifles, sharp tools, as well as stones and sticks. Farmer’s knowledge of Tapanuli Orangutan as a forest engineer is very low. Seventy three per cent of the respondent did not know any ecosystem services provided by Orangutans. We found out that cultural services of orangutans are the most understandable services by local farmers (14%), followed by regulation services (10%) and provisioning services as they consume the bushmeat of Orangutan (3%). Simultaneously, we found that knowledge, perceptions and attitude affect farmer actions by 62.2%. Understanding the farmer’s action against the Tapanuli Orangutan will provide vital information for the stakeholders. We suggested further research to determine farmers’ willingness to accept compensation for their crop-raiding by an Orangutan and the resolution conflict scheme of humanorangutan conflict. Using the economic valuation of orangutans, some strategic approaches may be taken to solve the conflict.

The effectiveness of artificial canopy bridges for the diurnal primates within a hydroelectric project in North Sumatra-Indonesia

Abstract Primates that live within fragmented and disturbed habitat are facing population declines and a higher probability of extinction due to gene flow inhibition. To address this problem, land managers, practitioners, and primatologists have applied several approaches to enhance primates’ habitat quality and connectivity through habitat restoration and canopy bridge installation. In some cases, artificial canopy bridges have shown to be effective to facilitate movement between fragmented habitats for several primates’ taxa. However, while several types of canopy bridge designs are available, there is no clear evidence on which is the best for primates. Here we evaluated the effectiveness of three artificial canopy bridge designs within a hydroelectric project in Sumatra, Indonesia from 2019 to 2021. The hydroelectric project was located at the edge of a forest block within the Batang Toru Ecosystem which could disconnect the primate’s population from this protected forest to the other forest blocks. During 595 days of camera trapping, we captured 988 independent crossing events from six diurnal primate species (Pongo tapanuliensis, Hylobates agilis, Symphalangus syndactylus, Presbytis sumatrana, Macaca nemestrina, and Macaca fascicularis). Our initial observation finds the ladder canopy bridge design was commonly used by primates and Presbytis sumatrana was the species that often crossed the canopy bridge. These findings are important to improve species management plans and primate conservation in Indonesia.

Phytochemical Analysis of the Feed of the Tapanuli Orangutan as a Continuing Conservation Effort

This study aims to determine the type of feed for the Tapanuli orangutan (Pongotapanuiliensis), and the phytochemical compounds contained in the diet of the Tapanuli orangutan (Pongotapanuiliensis). This research was conducted in the Batang Toru forest of South Tapanuli for sampling. This study used a line transect method with 4 transects I, II, III, IV) used to observe the diet of the Tapanuli orangutan, and the Physics Laboratory of the HKBP Nommensen Pematangsiantar University for phytochemical analysis. The results of this study obtained 11 types of nests HayunDolok (Syzygiumsp), Medang (Litseabrachystachys), Mayang (Palaquiumgutta), Laccatbodat (Shoreahopeifolia) and Hoteng (Quercusgemelliflora). Phytochemical compounds contained in orangutan feed are alkaloids, flavonoids, tannins and saponins.

Identification of plant constituents for tapanuli orangutan (Pongo tapanuliensis) nest in Batang Toru North Tapanuli

Tapanuli orangutan is an endemic animal in North Sumatra that must be protected so that conservation efforts are needed to preserve it. Tapanuli Orangutan nests are the focus of this research. This research is aimed to know the variety of constituents plant the nests of tapanuli orangutan (Pongo tapanuliensis), to know the kind of the most dominant plant to construct the nests by Tapanuli orangutan (Pongo tapanuliensis), the composition of constituents the nests of tapanuli orangutan (Pongo tapanuliensis) in North Tapanuli. This research was primery forest Batang Toru National Park. This research using line transect method with 4 transects (transects I, II, III, IV) were used to observe the nest tree and the nest constituent of Tapanuli orangutan. This research results is there are 5 species of of constituents plant the nests with quantity 14 nests. The most dominant tree nest is Syzygium sp (43%), Plant constituent orangutan nests also use the leaves of the Shorea hopeifolia (94.1%), as well as branches of Palaquium gutta (6.6%).

The estimation of demographic parameters and a growth model for Tapanuli orangutan in the Batang Toru Landscape, South Tapanuli Regency, Indonesia

Biological and ecological information on the Tapanuli orangutan (Pongo tapanuliensis) remains limited. This study was designed to analyze the demographic parameters and build a growth model of the Tapanuli orangutans to help guide policy in developing a conservation program for them. Data were collected from tapanuli orangutans that were directly observed over four years in the Batang Toru Landscape, South Tapanuli Regency, North Sumatra. There were 32 distinct individual orangutans, 27 of which were adults or sub-adults. Only five were children or infants. The adult sex ratio, male to female, was 1: 0.83, the birthrate was 0.13, and the highest mortality rate was among sub-adults and adults. The population growth rate (r) was estimated to be 0.051 per year and predicted to reach the potential carrying capacity of the habitat they now occupy in about 60–80 years from 2020. Conservation activities that might help to increase the tapanuli orangutan population include increasing the number of food plants in production forests around nature reserves and increasing patrols to monitor the population and minimize potential damage to the animal and their habitat due to human activities.

Population Status of Tapanuli Orangutan (Pongo tapanuliensis) within the Renewable Energy Development and its Management Implications

To protect Tapanuli orangutan it is essential to understand the actual situation. It has been studied 15% of its population live outside the protected area facing a density disruption due to forest conversion. Several best management practices have been created and tested for different natural concession types. Yet, the main objective to reduce the impact and increase wildlife survival is far away from the goal. To improve our understanding of the species survival within ongoing project construction, we conducted population density monitoring prior- to post-construction time frames within the hydroelectric dam project. Also, we carried out spatial analysis to understand the land cover change and orangutan’s suitable habitat distribution. This study found that during high construction activities, orangutans were avoiding the threat sources, and returned when the disturbances reduced. These findings indicated orangutans are ecology flexible and have the capability to increase its survival, although the company’s involvement is crucial to facilitate the successes. Our study is based on indirect observation, and spatial modeling, which may lead to an uncertain conclusion. Further research on orangutan ecology and behavior is prioritized.

Nest Characteristics of the Sumatran Orangutan (Pongo abelii) in the Wildlife Sanctuary Soraya Station in Aceh Province, Indonesia.

Orangutans (Pongo spp.) populations used to be widely distributed throughout Southeast Asia, from Java in the south to the Southern China in the north during the Pleistocene. Their populations have declined up to 75% of their original size and are now distributed only in parts of the tropical rainforests of Borneo and Sumatra. Pongo pygmaeus, Pongo tapanuliensis and Pongo abelii are the three most representative species, in this study, here we discussed the latter. Sumatran forests are generally suffering from deforestation with rates ranging from 3.74% to 49.85% between 2000 and 2012. Thus, human wildlife conflict intensity has escalated and gained more traction. Orangutans are known as arboreal great apes and need to build nests for resting. We applied the transect line method (three transects; each 1,000 m long) at different elevations in Soraya Research Station, Gelombang Village, Sultan Daulat sub-district, Subulussalam district, and assessed the nest characteristics. The characteristics are: (1) nesting position referring to the position of nest on a tree; (2) nest successional stages defining the age and leaf decay used in constructing a nest indicated with I (new) until V (almost gone); and (3) nest density to predict the density of nest per square km. Afterwards, the identified nesting trees along the transect were further identified based on their species, and assessed based on three characteristics (the tree height, diameter and the height of a nest measured from the soil). A total of 27 nests were found, and 44% were located in transect III or at the riparian. Out of 27, four orangutans’ nests were found on Moraceae (Streblus elongatus) and Myrtaceae (Syzigium spp.), while three nests were found on Dipterocarpus sp. The tree height, tree diameter and nest height were 10 m–25 m (mean = 17.5 m; SD = ± 0.25), 10 cm–30 cm (mean = 20 cm; SD = ± 0.4) and 16 m–20 m (mean = 18 m; SD = ± 0.35), respectively. Meanwhile, nest density calculated based on the form: d = [N/ (L* 2w)], and the values obtained were 8.4, 13.45, 26.9 nests/km2 located on transect I, II and III or at the riparian. The most commonly found nest successional stages and position were stage III and position 3, respectively. This study could serve as a baseline research in primate conservation and nest characterisation could be used as guidance for any future activity planning (e.g. tree reforestation) in a particular region and the existence of various tree species diversity are indispensable for maintaining orangutan habitats’ quality.

Vegetation diversity of feeding plant of Tapanuli Orangutan (Pongo tapanuliensis) in the land of other uses around the Batang Toru Forest Area, North Sumatera

The Tapanuli orangutan (Pongo tapanuliensis) is an endemic species found in the Batang Toru ecosystem. The population of Tapanuli orangutan is divided into two main regions (west and east blocks), and also a small population in the natural reserve. Its status based on the IUCN red list is classified as “Critically Endangered”. It is necessary to identify the diversity and abundance of forage vegetation for Tapanuli orangutan using vegetation analysis especially in other zones of Batang Toru forest area. All is related to the importance and urgency of Orangutan habitat protection. This research aimed to estimate the availability of forage sources of Orangutans particularly outside the protection area. It shows a total diversity index (H’) of 4.62, which means that the level of diversity is high. Consequently, protection efforts outside the conservation area are really needed to support Batang Toru ecosystem from land conversion threat that may cause negative impact on the sustainability of Orangutan habitat itself.

Characteristics of the Tapanuli Orangutan Habitat in the Conflict Area of Batang Toru Landscape, North Sumatra, Indonesia

Forest fragmentation has resulted in decreased wildlife habitat, which has triggered conflicts with humans due to the use of the same plants. This has been particularly contentious with the tapanuli orangutan. Research of the tapanuli orangutan (Pongo tapanuliensis) habitat is very limited. The aims of this research is to examine the latest habitat conditions, such as land cover, composition of vegetation, feed plant, and habitat carrying capacity to provide recommendations for habitat management in developing a mitigation policy of the human-tapanuli orangutan conflict. The research location is focused on the area of human-orangutan conflict in the Batang Toru Landscape in South Tapanuli Regency, which took place from August to December 2019. Vegetation analysis was conducted using the strip transect method with a total of 294 plots (11.76 ha). The number of species at the pole and tree levels were high with 149 species (46 families) and diversity index (H') > 3. Eighty feed plant species were found and expected to support the growth of the orangutan population of 247 individuals. The density and diversity of cultivated plant species in the buffer zone were high and consumption by orangutans resulted in human-tapanuli orangutan conflict, especially on durian (Durio zibethinus Murray). Conflict with humans will cause stress and disruption to the growth of the tapanuli orangutan. We recommend habitat management to mitigate conflict through patrols for monitoring habitat destruction in conservation forests, enrichment of feed plants in Forest Management Units, cultivation of orangutan non-food crops on community lands, and building a corridor with orangutan food crops with fruits that are not utilized by humans.

Characteristics and community perception on mitigation of Human-Tapanuli Orangutans conflict around Dolok Sipirok Natural Reserve, South Tapanuli

The frequency of human-tapanuli orangutan (Pongo tapanuliensis) conflict has been increased with the widespread on degradation and fragmentation at Batangtoru Forest, South Tapanuli Regency. Orangutans often come on community lands to look for food, especially while the durian fruit season. This study aims to obtain information on socio-economic characteristics and public perception index to mitigate on human-tapanuli orangutan conflict around the Dolok Sipirok Nature Reserve, South Tapanuli Regency. Data was collected using a questionnaire distribution, interviews and descriptive observations, starting from October 2019 to January 2020. Respondents were selected by purposively sampling method, i.e. people had met and interacted with orangutans as many as 61 respondents from three villages. Data analyzed using frequency tables, likers scale and spearman rank correlation. The results showed that the community is Muslim majority, productive age, education below senior high school, farmers and income below IDR. 4,000,000. The public perception has declared orangutans as animals that consume community plants. They will drive away the orangutans found in processed land. The perception of conflict mitigation has strongly agreed with the program that must be done including providing compensation for losses, increasing patrol programs, developing local wisdom and building corridors in state forests. The characteristics were a significant (α <0.01) influence on the perception index assessment i.e. the level of education, household member and family income.

The historical range and drivers of decline of the Tapanuli orangutan.

The Tapanuli Orangutan (Pongo tapanuliensis) is the most threatened great ape species in the world. It is restricted to an area of about 1,000 km2 of upland forest where fewer than 800 animals survive in three declining subpopulations. Through a historical ecology approach involving analysis of newspaper, journals, books and museum records from the early 1800s to 2009, we demonstrate that historically Pongo tapanuliensis inhabited a much larger area, and occurred across a much wider range of habitat types and at lower elevations than now. Its current Extent of Occurrence is 2.5% and 5.0% of the historical range in the 1890s and 1940s respectively. A combination of historical fragmentation of forest habitats, mostly for small-scale agriculture, and unsustainable hunting likely drove various populations to the south, east and west of the current population to extinction. This happened prior to the industrial-scale forest conversion that started in the 1970s. Our findings indicate how sensitive P. tapanuliensis is to the combined effects of habitat fragmentation and unsustainable take-off rates. Saving this species will require prevention of any further fragmentation and killings or other removal of animals from the remaining population. Without concerted action to achieve this, the remaining populations of P. tapanuliensis are doomed to become extinct within several orangutan generations.

The distribution and density of Tapanuli orangutans (Pongo tapanuliensis) at potential corridor locations between forest fragments in Batang Toru, North Sumatra, Indonesia

Abstract. Nasution A, Perwitasari-Farajallah D, Utami-Atmoko SS. 2020. The distribution and density of Tapanuli orangutans (Pongo tapanuliensis) at potential corridor locations between forest fragments in Batang Toru, North Sumatra, Indonesia. Biodiversitas 21: 5382-5388. The newly discovered Tapanuli orangutan (Pongo tapanuliensis) is in danger of being lost in a few decades due to their small population number in fragmented forest of Batang Toru. The major threats faced by this critically endangered ape, including: hunting, habitat loss, and fragmentation due to large infrastructure development and other developments in the key corridor area. The establishment of corridor and buffer zone is one such effort to maintain their population and bring them from the brink of extinction. Data on the population and distribution are needed to assess and provide baseline information for investigating the habitat condition of potential corridors and buffer zones. This study aimed to analyze population and distribution of Tapanui orangutan (Pongo tapanuliensis) in buffer zone and potential corridor of Batang Toru. Our study provides an initial dataset prior to the development of the hydrodam, which is important to understand the future post-development impact. The study was carried out in disturbed (Hutaimbaru and Bulu Mario) and undisturbed forest (Sitandiang and Hopong) of Batang Toru from June 2015 until February 2016. Orangutan nest, fig (Ficus spp.), and trees bearing fruit were recorded using a line transect method. This research showed that population and distribution of orangutan were influenced by forest conditions, threat level, and fruit availability. There were fewer nests per km2 in disturbed forest than in undisturbed forest, resulting in an orangutan density estimation to be 0.24 ind/km2, 0.14 ind/ km2 (Hutaimbaru and Bulu Mario) and 0.74 ind/km2, 0.36 ind/km2 (Sitandiang and Hopong). Number of nest in transects was influenced by the availability of fig class I and class II, but not fruit tree. The APL forest of Sitandiang is key area to connect the three populations of Tapanuli orangutan: east Batang Toru, west Batang Toru, and Sibualbuali. Furthermore, orangutan’s nests were encountered both in protected and non-protected forest, thus protection of such areas, especially areas including primary forest that harbor orangutan is essential for their long term survival. The conservation measures and action Tapanuli orangutan is alarming, thus we recommend all remaining habitat should be officially and strictly protected and collaboration work with multi-stakeholder is essential to establish the corridor as well as the strategic management plan of Tapanuli orangutan.

Tapanuli orangutan endangered by Sumatran hydropower scheme

The Tapanuli orangutan survives today in less than 1,200 km of rainforest in northern Sumatra, Indonesia, in an area known as Batang Toru, where it was scientifically discovered in 1997. Teeming with endangered fauna and flora, the Batang Toru forest has been partially felled and fragmented and parts of the remainder allocated to agriculture, mining, hydropower and geothermal-energy production. The Tapanuli orangutan is estimated to number just 767 individuals, divided among three subpopulations. Its total remaining habitat 10 is merely a tenth the size of Sydney, Australia.

Nest characteristics and populations of Tapanuli Orangutans in the conflict areas, Batangtoru Landscape, North Sumatra, Indonesia

Abstract. Kuswanda W, Harahap RH, Alikodra JS, Sibarani R. 2020. Nest characteristics and populations of Tapanuli orangutans in Batangtoru Landscape, South Tapanuli District, Indonesia. Biodiversitas 21: 3398-3406. Tapanuli orangutan (Pongo tapanuliensis) has been threatened to extinction due to conflicts with humans. Information on the orangutan characteristics in conflict areas at the Batangtoru Landscape is needed. Our research aimed to analyze the characteristics of nests, nest trees, and estimation of orangutan populations in conservation forests and buffer zones to develop conflict mitigation strategies in the Batangtoru Landscape, South Tapanuli District. A line transect method was used to count orangutan nests on 49 transects, starting from June 2019 to January 2020. Data were analyzed with descriptive statistics, frequency tables, Spearman correlation (rho), and the equation by (van Schaick et al. 1995). Tapanuli orangutans make nests at the height of 14.01 meters (90% CI = 13.37-14.67 meters), and most use the main stem as nest support. Tree nests of 35 species (17 families) were identified, with the highest frequency in (Durio zibethinus Murray), especially in the buffer zone. Correlation between nest tree diameter, tree height, and canopy area was significant (p &lt;0.01, n = 83). The estimated orangutan populations in conflict areas were 155 individuals (95% CI = 121-187), and the highest was found in Dolok Sibualbuali Nature Reserve buffer zones. Mitigation strategy of human-orangutan conflict that needs to be realized is the non-cash compensation guaranteeing the community does not disturb orangutans on their land. The compensation forms can be the provision of seedlings and fertilizer for plants, agricultural machinery, knowledge to land management, and orangutan ecotourism development. Nest and feed trees enrichment can be carried out in production forests bordering with conservation area.

Giraffe taxonomy, geographic distribution and conservation

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