Hylobates Moloch Research Articles

Considering management context when investigating behavioral profiles in a group of captive Javan gibbons (Hylobates moloch)

ABSTRACT Effective animal husbandry aims to produce behavioral profiles consistent with those observed in wild counterparts. However, few studies have examined the impacts of management history on sociality. We investigate social dynamics in a group of Javan gibbons (Hylobates moloch) at Perth Zoo using behavioral and proximity data. The group consists of an aging adult female and her two offspring – a maturing sub-adult female and a juvenile male. This composition diverges from commonly observed groupings in the wild. The study group’s social relationships generally align with species-typical behaviors, with the exception of the patterning of play behavior and resting-in-contact. These results indicate an uncharacteristically close bond between the mother and her maturing same sex-offspring, as well as an unexpectedly distant mother-juvenile bond. These relationships are best explained by the group’s management history and resulting atypical group composition including: the absence of an adult male, the mother’s advanced age, and the hand-rearing of the juvenile male. This study gives insight into the effects of a captive setting on social development and provides further evidence of social flexibility in gibbons.

ASSESSMENT OF ACUTE PHASE PROTEINS AND PROTEIN ELECTROPHORESIS IN HEALTHY GIBBONS (HYLOBATIDAE) IN MANAGED SETTINGS.

Acute phase proteins (APP) and protein electrophoresis (EPH) offer crucial insights into inflammation and overall health in various species. In this study, we validated serum amyloid A (SAA) and C-reactive protein (CRP) reagents for use with serum samples from gibbons (Hylobatidae, n = 50), spanning five species across four gibbon genera: eastern hoolock (Hoolock leuconedys), Javan (Hylobates moloch), pileated (Hylobates pileatus), siamang (Symphalangus syndactylus), and white-cheeked (Nomascus leucogenys). Preliminary reference intervals (n = 50) were calculated for SAA (1.8-48.1 mg/L), CRP (0.1-11.1 mg/L), and EPH via capillary zone electrophoresis, in healthy gibbons. Comparing clinically normal (n = 38) and abnormal (n = 12) individuals, significant differences were observed in the albumin/globulin ratio (P = 0.0003), prealbumin (P = 0.0345), and albumin (P = 0.0094), with abnormal individuals exhibiting statistically significantly higher γ-globulins (P = 0.0224), SAA (P = 0.0001), and CRP (P = 0.0003). Despite significant chromosomal rearrangements among different gibbon species, we found no statistically significant differences of SAA and CRP levels across species. However, some differences between species were observed in EPH fractions. This study presents the first report of the evaluation of APP and EPH in gibbons, underscoring the potential use of these biomarkers in gibbon health monitoring. Further research with larger sample sizes of both normal and abnormal gibbons is recommended to solidify the clinical utility of these biomarkers in these species.

Endoparasites of Wild Javan Gibbon (Hylobates moloch) At Gunung Halimun Salak National Park, Indonesia

Infections of endoparasites in primates in natural habitats are highly prevalent and can cause disease, reduce health quality, and disrupt their life. This study investigated endoparasites prevalence value in the endangered Javan gibbon (Hylobates moloch) in Citalahab Forest, Gunung Halimun Salak National Park, Indonesia, from June to August 2022 by collected fecal samples (N = 10) and analyzed it using floatation methods. As a result, we found five genera of nematodes Trichuris trichiura (10% egg worm prevalence, Oesophagostomum spp. (50%), Trichostrongylus spp. (60%), Ancylostoma spp. (80%), and Strongyloides spp. (100%). The prevalence value of the worms in the larvae stage of Trichostrongylus spp. 20% and Strongyloides spp. 70%. Nematode infection status successively is Strongyloides spp., which is, frequently; Trichostrongylus spp. and Ancylostoma spp., which is, often; Oesophagostomum spp. and Trichuris trichiura which is, occasionally. Four species of nematode were found in both ages, and only Trichuris trichiura was found in one adolescent individual. The threat posed by this parasite deserves attention; further research is needed to fill the gap in our knowledge of their pathogenicity and transmission in Javan gibbon.

Analysis Of The Edge Effect On Bird And Primate Distribution In The Ecological Corridor Habitat Of Mount Halimun Salak National Park (TNGHS)

This study aims to analyze the threat of edge effects on endemic animal populations due to the presence of causeways in the TNGHS corridor habitat. Indicators of the occurrence of edge effects are characterized by the further distance of wildlife populations from sources of disturbance such as noise, light, and frequency of human activity mechanisms. Belt transect research method for population study and distribution of Javan Gibbon and Surili. Intensive Point Account (IPA) to measure the diversity index of bird species and Javan eagles. Encounter Rate is used for animal distribution studies. Results On the observation transect made along 3 km, the population density of Javan Gibbons was obtained 0.114 ind/ha, Surili 0.024 indv/ha, and Monkey 0.028 indv/ha. Bird species diversity index in 3 habitat patches each Purasari H'= 2.78 with 38 species; Garehong with 27 species, and Corridor H'= 3,087 with 27 species. The similarity of species is that there are only 7 species of birds found in the 3 habitats of the patch. As a result of primate population density and burng species similarity, it can be concluded that the cross-corridor access road area has experienced an edge effect and tends to be a bottle-neck area for the distribution of animals, especially primates.

Identifying Important Areas for the Release of Five Endemic Species in a Mountainous Landscape: Inference from Spatial Modeling Techniques

Efforts to release animals resulting from evacuation and rehabilitation into their natural habitats are important practices in wildlife conservation. Before releasing the animals, it is important to assess the habitat suitability of the areas to support the existence of the animals in the long run. Yet, there is limited study of habitat suitability assessment on national parks as release locations for wild animals. This study aimed to assess the suitable habitat of five charismatic animal species, i.e., Panthera pardus melas, Hylobates moloch, Prinonailurus bengalensis, Nycticebus javanicus, and Nisaetus bartelsi, in Gunung Halimun Salak National Park using Maxent, and to determine potential locations for releasing animal’s species. Models for the P. p. melas show 47,619 ha and 21,391 ha, respectively, suitable as habitat and potential release location, for H. moloch, each is 57,537 ha and 33,471 ha, for P. bengalensis, each is 25,460 ha and 17.189 ha, for N. javanicus, each is 29,848 ha and 15,578 ha, and for N. bartelsi, each is 44,426 ha and 25,660 ha. Our study shows that a suitable habitat can be critical in choosing a wildlife release site. Further consideration of conflict mitigation and practicalities is required to achieve the long-term existence of released species.

Identification of Digestive Tract Worms in Javan Gibbons (Hylobates moloch) at Maharani Zoo

Worm infections in Javan gibbons often do not cause clinical symptoms, but have an impact on the health and performance of Javan gibbons, so a fecal examination is needed to determine the presence of worm infections in Javan gibbons. The aim of this research is to identify digestive tract worms that infect Javan gibbons at Maharani Zoo. The research was conducted on 3 Javan gibbons consisting of 2 males and 1 female with an age range of 6-14 years and a body weight of 4-6 kg. Macroscopic identification of worms in Javan gibbons showed an abnormality in one of the Javan gibbon's feces. The feces abnormality is in the form of a very soft consistency, with a brownish yellow color, and the feces has a foul odor. Microscopic identification of worms in Javan gibbons showed positive results for the presence of eggs and larvae Strongyloides in one of the Javan gibbons. The Strongyloides worm larvae identified were rhabitiform. The cause of worm infections in Javan gibbons was due to the vegetable feed given, namely water spinach and mustard greens, being contaminated with Strongyloides worm eggs. Prevention needs to be done to prevent contamination of worm eggs, including washing the vegetables.

The Modelling Studies of Ecological Corridor Management of The Gunung Halimun Salak National Park, West Java, Indonesia

This research aims to study the design of the ecological corridor management pattern of Gunung Halimun Salak National Park (TNGHS) through the identification of population and distribution of conservation species, edge effect of road access within the corridor, preservation mitigation, status of non-conservation species, and assessment of land-use-based ecotourism. The methods used include Belt transect, hypothetical transect, Intensive Point Account (IPA), and descriptive survey techniques. The research was conducted from September to December 2023. The results showed that the population density of Javan Gibbon was 0.114 indv/ha, Surili was 0.024 indv/ha, which is very low compared to the population density of TNGHS, 26 non-conservation bird species, and 1 endemic species, the Javan Gibbon. The edge effect is caused by the frequency of vehicles passing through the corridor. The hypothetical transect shows that the land use allocation for tea plantations is the target of ecotourism, and agricultural land use supports the product. The model design emphasizes the creation of protection zones for primates and Javan Eagles in terms of mobilization and migration, mitigation of vehicle crossings during the day, as well as the initiation of ecotourism based on non-conservation species and landscape characteristics. In conclusion, the ecological corridor management modeling includes accommodating the protection of endemic and rare animals, monitoring non-conservation bird species, conservation mitigation through vehicle frequency control, limited ecotourism development with a natural orientation, and agricultural products. Scientifically the contribution of this research is to explain the implications of island geography theory in the sustainability of endemic species in metapopulations to avoid genetic flow deviations.

The Javan Gibbon (Hylobates moloch) Habitat Changes and Fragmentation in the Dieng Mountains, Indonesia

The endangered javan gibbon (Hylobates moloch) has been threaten by massive habitat loss and fragmentation in Java. The survival of the second largest population which inhabited unprotected Dieng mountains faced greater risk to habitat conversion and fragmentation. The landscape-level habitat monitoring using spatiotemporal quantification is crucial as a baseline data for javan gibbon conservation. Here, the land-use and land-cover (LULC) change of the Javan gibbon habitat during 1994–2009–2021 and its fragmentation in the Dieng mountains were quantified. This study revealed there were no significant decline in the total of forest. However, its quality was degraded in the interior of forest block. The forest has more fragmented from large patches into smaller patches and increased forest edge. The higher fragmentation happened in the areas that traversed by road. Six suitable forest blocks were identified with varying level of connectivity. Protection and restoration both in the forest and in the interior forest is immediate need, especially in the main forest block. The extra effort is also crucial in the connected forest but traversed by road. The blocks which closely isolated by road could be potentially reconnected by artificial canopy bridge, while the other distantly isolated block might need habitat restoration for corridor.

Predicting suitable habitat for the endangered Javan Gibbon in a submontane forest in Indonesia

Species distribution modeling is an essential tool for understanding the ecology of species and has many applications in conservation. Using maximum entropy (MaxEnt) modeling, we identify the key factors shaping the potential distribution of the endangered Javan Gibbons Hylobates moloch in one of the main remnant habitats, Gunung Halimun Salak National Park (GHSNP), Indonesia, using presence-only data collected between October and November 2015, and in April and May 2016. Maxent results showed that forest canopy density and annual temperature were the principal variables predicting the distribution of Javan Gibbons, with contribution scores of 53.9% and 35.6%, respectively. The predictive distribution map indicated that suitable habitat for Javan Gibbons is not uniformly distributed within GHSNP, i.e., suitable habitat is not located evenly throughout the region, with some areas more suitable than others. Highly suitable habitat comprises the largest proportion of habitat, with 42.1% of GHSNP classified as highly suitable habitat, whereas 24.7% was moderately suitable, and 33.2% of habitat was of low suitability for Javan Gibbons. Priority should be given to increasing habitat quality in degraded areas and law enforcement patrols to reduce degradation in peripheral regions of the park as part of the conservation management strategy.

Population of the Javan Gibbon (Hylobatesmoloch) in the Dieng Mountains, Indonesia: An updated estimation from a new approach.

The Javan gibbon (Hylobatesmoloch) is endemic to the island of Java and its distribution is restricted from the western tip of Java to the Dieng Mountains in Central Java. Unlike the other known habitats that hold a large population of Javan gibbons, the Dieng Mountains have not been protected and experience various threats. This study, which was conducted in 2018 and 2021, aimed to provide an update of the current density and population size of Javan gibbons in Dieng after the most recent study in 2010 and to investigate their relationships with habitat characteristics (vegetation and elevation). The triangulation method and a new acoustic spatial capture-recapture method were used to estimate group density. A new approach for extrapolation, based on the habitat suitability model, was also developed to calculate population size. The results show that the Javan gibbon population in the Dieng Mountains has most likely increased. The mean group density in each habitat type was high: 2.15 groups/km2 in the low suitable habitat and 5.55 groups/km2 in the high suitable habitat. The mean group size (3.95 groups/km2, n = 20) was higher than those reported in previous studies. The overall population size was estimated to be 1092 gibbons. This population increase might indicate the success of conservation efforts during the last decade. However, more effort should be made to ensure the long-term future of this threatened species. Although the density significantly differed between habitat suitability types, it was not influenced by the vegetation structure or elevation. A combination of multiple variables will probably have a greater effect on density variation.

Intra-group competition and social dynamics regarding dispersal and maturation in wild Javan gibbon (Hylobates moloch)

Natal dispersal is an important life-history trait in all animal taxa. In pair-living species, parent–offspring competition derived from the offspring’s maturity can motivate the natal dispersal of offspring. However, not much has been known about the dispersal mechanisms of pair-living gibbons. To test food and mate competition as potential reasons for dispersal, we investigated the effect of the offspring age and sex on relationships between parents and offspring in wild Javan gibbon (Hylobates moloch) in Gunung Halimun-Salak National Park, Indonesia. We collected behavioral data for two years between 2016 and 2019. We found that aggression from parents toward offspring increased in both feeding and non-feeding context as the offspring got older. Offspring received more aggression from the parent of the same sex in the general context. While offspring decreased co-feeding and grooming time with parents as they got older, there was no change in the proximity and approach to parents. The results imply the presence of both intra-group food and mate competition which increase with the offspring’s age. We highlight that increased competition between maturing offspring and parents changes their social relationships and peripheralizes offspring from the natal group which will eventually motivate offspring to disperse in Javan gibbons.

Formulating the Direction of Community Land Use to Support the Conservation of Javanese Gibbon (Hylobates moloch) Habitat at Petungkriyono, Central Java

The Petungkriyono forest is one of the few remnant tropical forests on the island of Java, particularly in Central Java. This forest is known for its high conservation value due to its abundance of biodiversity, particularly the endangered Javan gibbon or Owa Jawa (Hylobates moloch). The Petungkriyono people, on the other hand, rely on upland agriculture and cultivation on steep slopes as a means of subsistence, which poses a threat to the Petungkriyono forest. This paper aims to formulate the direction of the community land use at the habitat of Javanese gibbon at Petungkriyono. The method used the Spatial Multi-Criteria Analysis (SMCA). SMCA was applied to create the initial model of the zoning description of sustainable land use in Petungkriyono. The SMCA analysis process includes goal setting and conceptualization, data collection, analysis, field ground checks, and Focus Group Discussions (FGD) with the community and related parties. The result showed that considering the massive changes of land use at Petungkriyono almost 70% of the area is formulated for perservation and protection to support the conservation of Javan gibbon.

Population Monitoring of Javan Leopard and Javan Gibbon in Potential Areas in Mount Halimun Salak National Park

Mount Halimun Salak National Park (MHSNP) is one of tropical forest area in West Java which has the potential for a high diversity of flora and fauna species. One of them is an important habitat for the Javan leopard and Javan gibbon. This study aims to analyze the population density of the Javan leopard and Javan gibbon. Based on the result of this study information on the population condition of the Javan leopard and Javan gibbon in MHSNP. The data collection was conducted in February – April 2021 in Cikaniki area, Citalahab, corridor, and MHSNP Star Energy by installing camera traps and line transect method. The results of the camera trap installation could detected 12 types of mammals and 5 species of birds. There are four Javan leopard identified in this study with a sex ratio of 3 males and 1 famale (3:1) and only had one age class (adult). The estimated density of the Javan leopard by SECR is 11,19 ind/100km2. There were at least 11 javan leopards in an area 100 km2. The population density of javan gibbon in Cikaniki is 26,67 ind/km2, Citalahab is 16,67 ind/km2, and Star Energy is 8,33 ind/km2.

Hylobates moloch(Primates: Hylobatidae)

AbstractHylobates moloch (Audebert, 1797), the Javan or silvery gibbon, is a pair-living small ape which is exclusively found in the western and central regions of the Indonesian island of Java. It represents the southernmost occurring species of the genus Hylobates and inhabits the canopy of tropical rainforests. It is foremost characterized by its long silvery-gray fur in combination with a lack of duet songs in mated pairs. Hylobates moloch is threatened by habitat loss as well as the illegal wildlife trade and is listed as “Endangered” (EN) by the IUCN Red List of Threatened Species.

Identification and prevalence of soil-transmitted helminth eggs in Javan gibbon (Hylobates moloch) and Javan langur (Trachypithecus auratus) at Petungkriyono Forest, Central Java, Indonesia

Abstract. Kharismawan MYK, Maula I, Astuti P, Setyawan A. 2022. Identification and prevalence of soil-transmitted helminth eggs in Javan gibbon (Hylobates moloch) and Javan langur (Trachypithecus auratus) at Petungkriyono Forest, Central Java, Indonesia. Biodiversitas 23: 4501-4509. Javan gibbon (Hylobates moloch) and Javan langur (Trachypithecus auratus) are arboreal primates found at Petungkriyono Forest, Central Java, Indonesia. An increase in ecotourism activity in Petungkriyono Forest affected wildlife behavior and forest landscape along the road. Canopy connections separated by the main road is essential for both of these primates They were spotted foraging food and moved across the separated habitat using available canopy. Based on their activity and habitat along the main road, this research is conducted to identify and count the prevalance of soil-transmitted helminth eggs in their gastrointestinal through their feces. A total of 72 Javan gibbon and 46 Javan langur fecal samples were collected under 10% formalin preservation. Fecal samples were examined using the mini-FLOTAC method for Javan gibbon and the flotation method for Javan langur. The results indicate three orders, including Enoplida, Strongylida, and Rhabditida, were found and the prevalence of helminthiasis is 31.94% for Javan gibbon and 47.82% for Javan langur. Eventhough both of these primates helminthiasis prevalance is considered to be low, higher prevalance in Javan langur was caused by its behavior to be less arboreal than Javan gibbon.

Whole-genome sequence and assembly of the Javan gibbon (Hylobates moloch).

The Javan gibbon, Hylobates moloch, is an endangered gibbon species restricted to the forest remnants of western and central Java, Indonesia, and one of the rarest of the Hylobatidae family. Hylobatids consist of 4 genera (Holoock, Hylobates, Symphalangus, and Nomascus) that are characterized by different numbers of chromosomes, ranging from 38 to 52. The underlying cause of this karyotype plasticity is not entirely understood, at least in part, due to the limited availability of genomic data. Here we present the first scaffold-level assembly for H. moloch using a combination of whole-genome Illumina short reads, 10X Chromium linked reads, PacBio, and Oxford Nanopore long reads and proximity-ligation data. This Hylobates genome represents a valuable new resource for comparative genomics studies in primates.

Transient co-singing of offspring and mothers in non-duetting Javan gibbons (Hylobates moloch)

While the vocalizations of non-human primates were thought to be innate, recent studies have revealed highly flexible vocalizations in immatures. This behavior suggests that social influences have an important role in developing vocalizations. Yet not much is known about how non-human primate vocalization develop and how the vocalizations of immature animals differ between sexes. Here, we analyzed 95 cases of co-singing between mothers and offspring out of 240 female songs from three groups of wild Javan gibbon (Hylobates moloch) in Gunung Halimun-Salak National Park, Indonesia, between 2009 and 2021. Hylobates moloch is one of only two gibbon species with pairs that do not duet. Instead, they produce sex-specific solo songs. We found that both offspring female and male H. moloch follow their mothers’ female-specific songs, similar to other duetting gibbon species. Immatures started co-singing with their mothers from 7 months old, but with an average starting age of about 24 months. As female offspring grew older, they co-sung with mothers more often while male offspring did not. After 7 years of age, both sexes stopped co-singing with their mothers and started singing alone, following their own sex-specific vocalizations. We did not find any relation between male offspring co-singing and territorial functions (e.g., co-singing more during intergroup encounters or closer to home range borders). Our results suggest that mothers’ songs may trigger male offspring and females to practice singing, but not specifically for males to defend territories. We highlight that despite the absence of duets, H. moloch develop their vocalizations from early infancy and throughout their maturation while co-singing with mothers. However, the level of co-singing varies depending on the sexes. Our study is the first to elucidate the sex-specific trajectories of vocal development in H. moloch across years, indicating that offspring in non-duetting gibbons co-sing with mothers like in duetting species.

Cases of fatal electrocution of the endangered Javan Gibbons (Mammalia: Primates: Hylobatidae) by power lines

Human-made structures are often deadly to wildlife. Power lines from electric poles can cause serious injury and even death of wildlife via electrocution, especially of arboreal primate species that can easily access power lines. Here, we reported three cases of wild ‘Endangered’ Javan Gibbons Hylobates moloch electrocuted by power lines along a road between a tea plantation and a village adjacent to Gunung Halimun-Salak National Park area, West Java, Indonesia. In all cases, the adult male Javan Gibbons jumped and grabbed a power line hanging at the edge of the forests and immediately died. Our case reports highlight that power lines can have a critically adverse effect on the survival of wild animals, particularly on highly arboreal species such as Javan Gibbons. We argue the need for mitigation plans (e.g., cable insulation) for power lines in areas at risk. Such areas should be determined based on wildlife habitat monitoring and the study of ranging behaviors, focusing on areas with high risks of electrocution.

AKTIVITAS HARIAN OWA JAWA (Hylobates moloch) DI PUSAT REHABILITASI SATWA PRIMATA JAWA CIWIDEY JAWA BARAT

Owa jawa (Javan gibbon) is one of endemic primate of West Java that is vulnerable to extinction. In connection with the decline in the species population, conservation efforts need to be taken immediately, one of the supporting aspects is information about daily activities. The object of research is to identify the daily activities of javan gibbon in Javan Primate Rehabilitation Centre Ciwidey, West Java. The method of resesarch is recording of activities of each individual is carried out for seven days at intervals of 5 minutes. The result is javan gibbon daily activities in the Javan Primate Rehabilitation Center were 5945 times carried out by 3 javan gibbon individuals with eight observed activities, are eating, drinking, moving, grooming, urination, defecation, sound and rest, which began at 06.00 WIB and ended in the afternoon at 16.00 WIB. The number of daily activities from the highest to the lowest are 2596 times (43.66%) mobile activity, 2189 times (36.82%) resting activities, 593 meals (9.97%), 353 times grooming (5.93%), vote 95 times (1.59%), urinate 44 times (0.74%), drink 39 times (0.65%) and defecate 36 times (0.60%).

Endangered Apes—Can Their Behaviors Be Used to Index Fear and Disturbance in Anthropogenic Landscapes?

Behaviors exhibited by prey species towards predators (including humans) can reduce feeding time and increase time spent in vigilance, thereby impacting animal condition and ultimately limit populations, even when actual mortality from predation is low. Here, we test whether behavioral profiles in an endangered ape, Javan gibbons (Hylobates moloch), correspond to varying degrees of human disturbance in a human-impacted sacred forest, Cagar Alam Leuweung Sancang, West Java. Data were collected August 2010–July 2011. Although all groups reacted differently to human presence, overall, gibbons responded by reducing time spent on conspicuous behavior (e.g., vocalizing, feeding, traveling, and social interactions) as the number of humans in the area increased or distance to the nearest human decreased. In addition, gibbon responses to encountering humans were also more like their responses to encountering potential predators than they were to encountering monkeys or other gibbons. These results support the hypothesis that as human presence and encounter rates increase, gibbons alter their behavior in ways consistent with anti-predator behaviors. Assessing how this endangered species responds to human presence is a vital part of their ultimate conservation.