Hylobates Klossii Research Articles

Genetic characterization based on the D-loop MtDNA and the TSPY genes of the Dwarf Siamang (Hylobates klossii) of Mentawai Island, Indonesia

Abstract. Hasanah R, Saepuloh U, Perwitasari-Farajallah D, Sinaga W, Hastuti Y, Sajuthi D. 2020. Genetic characterization based on the D-loop MtDNA and the TSPY genes of the Dwarf Siamang (Hylobates klossii) of Mentawai Island, Indonesia. Biodiversitas 21: 2854-2861. Hylobates klossii is an endemic primate on the Mentawai Island, Indonesia that categorized as endangered species due to fragmentation, illegal hunting, and habitat loss. This study aimed to analyze the genetic characterization of H. klossii based on maternal and paternal lineages. The samples were collected from TSI (Bogor, Indonesia) cage consist of two males and two females (blood and fecal of four individuals) and Siberut Island, Mentawai, West Sumatra, Indonesia from one unknown gender (one individual fecal sample). PCR amplification was carried out on DNA and cDNA samples using specific primers for D-loop MtDNA and TSPY genes. The amplicon was analyzed with MEGA-7. The dimensional structure model of the TSPY protein was determined using I-TASSER and visualized with PyMol. The maternal analysis showed five samples consisted of four haplotypes revealed that Nam-nam and April were identic with 0% genetic distance. It’s revealed that Nam-nam and April were mother and son. The paternal analysis of two H. klossii males revealed that April was the closest relative to H. muelleri (99.56% identity) and Gou-gou to H. klossii (100% identity). Characterization of partial TSPY gene (990 bp) of April and Gou-Gou indicated four amino acids mutation, causing the shift in-amino acid structure position. The results assumed that April was a cross-breeding between H. klossii female and H. muelleri male. This genetic characterization is expected to support the conservation efforts through recommendations for good management in H. klossii preservation.

Distribution survey of Kloss’s Gibbons (Hylobates klosii) in Mentawai Islands, Indonesia

Abstract. Setiawan A, Simanjuntak C, Saumanuk I, Tateburuk D, Dinata Y, Liswanto D, Rafiastanto A. 2020. Distribution survey of Kloss’s Gibbons (Hylobates klosii) in Mentawai Islands, Indonesia. Biodiversitas 21: 2224-2232. The aim of this study was to assess the population density, distribution, habitats, and threats of Kloss’s gibbon (Hylobates klossii) in the Mentawai Islands, Indonesia. In 2011-2012 we conducted a survey on Siberut Island, outside of the National Park, as well as a short visit to Sipora, North Pagai, and South Pagai. From March to September 2017, we surveyed once again some previous localities on the Siberut and Sipora islands to keep up to date with recent developments on the ground. On Siberut we used an auditory sampling method through fixed point counts, combined with line transects, to estimate the gibbon densities. In total, 113-morning calls were recorded from 13 Listening Points; 75 of these were used for density calculations. We recorded 35 individuals based on direct sightings during 66.4 km of transect distance walked. We found 13 localities outside of Siberut National Park that still have Kloss's gibbons; densities varied between 1.04group/km2 to 4.16 group/km2. No gibbons were found and heard during the short survey in Sipora and South Pagai, though we found a group of gibbons in North Pagai. Our 2017 survey revealed massive habitat changes in South Siberut. Previously existing forest localities in South Siberut were gone due to road construction, agriculture expansion, and logging.

Population Density of Kloss’s Gibbon (Hylobates klossii) at Bojakan Resort, Siberut Island, West Sumatra

Bilou (Hylobates klossii) merupakan satwa primata endemik Kepulauan Mentawai, Sumatera Barat dan ditetapkan sebagai satwa primata dengan status terancam/genting (endangered) berdasarkan kategori IUCN (International Union for Conservation of Nature and Natural Resources) tahun 2008. Saat ini, informasi populasi bilou terbaru di Pulau Siberut belum diketahui secara lengkap dan menyeluruh. Penilaian terhadap populasi dijadikan sebagai landasan dalam menentukan strategi konservasi. Penelitian bertujuan mengidentifikasi populasi bilou yang meliputi distribusi populasi, kepadatan individu, kepadatan kelompok, ukuran kelompok, serta komposisi kelompok. Penelitian dilaksanakan di Resort Bojakan, Taman Nasional Siberut, Pulau Siberut, Kepulauan Mentawai, Sumatera Barat pada bulan November 2018 sampai Januari 2019. Pengamatan dan pengukuran parameter populasi bilou dilakukan dengan metode line transect sampling. Total perjumpaan dengan bilou sebanyak 77 individu dengan jumlah 25 kelompok. Nilai kepadatan individu 12,8 individu/km2, dan kepadatan kelompok 4,2 kelompok/km2. Rerata ukuran kelompok bilou di Resort Bojakan 3,08 individu/kelompok. Keberadaan populasi bilou di Resort Bojakan dipengaruhi akibat adanya gangguan aktivitas manusia. Kepadatan populasi bilou di Resort Bojakan lebih tinggi dibandingkan dengan penelitian-penelitian sebelumnya di wilayah Pulau Siberut. Persentase kelompok bilou yang memiliki ukuran kelompok lebih dari dua individu lebih tinggi dibandingkan kelompok dengan jumlah dua individu, yang menandakan kawasan Taman Nasional Siberut terutama di Resort Bojakan mendukung pertumbuhan populasi bilou. Proses regenerasi bilou masih terus berlangsung karena jumlah kelompok yang memiliki minimal satu keturunan atau lebih masih cukup banyak. Pemantauan dan patroli oleh pihak Taman Nasional diperlukan untuk memastikan keberadaan populasi bilou di Resort Bojakan.
 
 Kata kunci: primata endemik, bilou, metode garis transek, monogami

Knowledge, attitudes and practices of local people on Siberut Island (West-Sumatra, Indonesia) towards primate hunting and conservation

The Mentawai Archipelago (West-Sumatra, Indonesia) harbours a wealth of endemic animals and plants including six unique primate species, all threatened by habitat loss and hunting. Although hunting is known to be widespread, little systematic work has been carried out to examine its scale and impact on Mentawai´s primate populations. Here we report an island-wide survey carried out on Siberut, the archipelago’s largest island, to assess hunting behaviour with respect to the four locally-occurring primate species, as well as the attitudes of indigenous inhabitants to resource utilization. Face-to-face interviews were conducted in mid-2012 with 390 respondents from 50 villages using a structured questionnaire. Overall, ca. one quarter of the respondents (24%) are still active hunters, generally targeting Simias concolor (77%), Macaca siberu (71%) and Presbytis siberu (68%); Hylobates klossii is rarely hunted (3%). Mostly, a single animal is captured per hunt, with average numbers per three months ranging from 1.9-2.3 individuals (for S. concolor , M. siberu and P. siberu ). We found that in many aspects our data did not differ between the protected area (Siberut National Park) and the rest of the island, although hunting was significantly more prevalent within the protected area’s boundaries. Our approximation of annual offtake leads us to conclude that no less than 4,800 primates are taken every year (min. 6.4 % of the population). We provide recommendations on how to reduce hunting as a driver for population decline.

Kloss gibbon (Hylobates klossii) behavior facilitates the avoidance of human predation in the Peleonan forest, Siberut Island, Indonesia.

Kloss gibbons (Hylobates klossii) are endemic to the Mentawai Islands in Indonesia and have been subject to human predation for more than 2000 years in the absence of any other significant predators. We investigate the behavior of Kloss gibbons that may be attributed to avoiding human predation. We observed Kloss gibbons in the Peleonan forest in the north of Siberut Island, the northernmost of the Mentawai island chain, over 18 months in 2007 and 2008, and collected data on their singing behavior, the number of individuals present during different conditions and their responses to humans. We examine behaviors that may reduce the risk of predation by humans during singing (the most conspicuous gibbon behavior), daily non-singing activities and encounters with humans. The individual risk of being stalked by hunters is reduced by singing in same-sex choruses and the risk of successful capture by hunters during singing is reduced by singing less often during daylight hours and by leaving the location of male pre-dawn singing before full light (reducing the visual signal to hunters). Groups in the Peleonan also fission during non-singing daily activity and rarely engage in play or grooming, enhancing the crypticity of their monochromatic black pelage in the canopy. We also observed a coordinated response to the presence of humans, wherein one adult individual acted as a "decoy" by approaching and distracting human observers, while other group members fled silently in multiple directions. "Decoy" behavior occurred on 31% of 96 encounters with unhabituated Kloss gibbons that detected our presence. "Decoy" individuals may put themselves at risk to increase the survival of related immatures (and adult females with infants) who have a greater risk of predation. We argue that, in combination, these behaviors are an evolved response to a long history of predation by humans.

Line Transect and Triangulation Surveys Provide Reliable Estimates of the Density of Kloss' Gibbons (Hylobates klossii) on Siberut Island, Indonesia.

Estimating population densities of key species is crucial for many conservation programs. Density estimates provide baseline data and enable monitoring of population size. Several different survey methods are available, and the choice of method depends on the species and study aims. Few studies have compared the accuracy and efficiency of different survey methods for large mammals, particularly for primates. Here we compare estimates of density and abundance of Kloss’ gibbons (Hylobates klossii) using two of the most common survey methods: line transect distance sampling and triangulation. Line transect surveys (survey effort: 155.5 km) produced a total of 101 auditory and visual encounters and a density estimate of 5.5 gibbon clusters (groups or subgroups of primate social units)/km2. Triangulation conducted from 12 listening posts during the same period revealed a similar density estimate of 5.0 clusters/km2. Coefficients of variation of cluster density estimates were slightly higher from triangulation (0.24) than from line transects (0.17), resulting in a lack of precision in detecting changes in cluster densities of <66 % for triangulation and <47 % for line transect surveys at the 5 % significance level with a statistical power of 50 %. This case study shows that both methods may provide estimates with similar accuracy but that line transects can result in more precise estimates and allow assessment of other primate species. For a rapid assessment of gibbon density under time and financial constraints, the triangulation method also may be appropriate.

Singing by male and female Kloss gibbons (Hylobates klossii) in the Peleonan Forest, Siberut Island, Indonesia

Kloss gibbons (Hylobates klossii) are endemic to the Mentawai Islands in Indonesia and are one of only two gibbon species in which mated pairs do not sing duets. This is the first long-term study of the factors influencing the singing activity of Kloss gibbons within a northern Siberut Island population and follows two previous studies in central Siberut nearly 30years ago. We collected data on the presence/absence of male and female singing within the study area on 198days and within a focal group on 47days. Rainfall during the time period in which they normally sing inhibits singing in both males and females. Our study supports the hypothesis that male and female songs function in intrasexual resource defence, as singing is associated with singing by same-sex neighbours, and same-sex choruses are more likely to occur after one or more days of silence (from that sex), suggesting there is pressure for individuals to communicate with same-sex neighbours regularly. Singing was not coordinated within a mated pair, suggesting that vocal coordination of the pair has been lost with the loss of the duet and that Kloss gibbon songs do not convey information to neighbours about the strength of the pair bond. On days when males sang predawn, females were more likely to sing after dawn and earlier in the morning. Additionally, the number of groups singing in female choruses was positively associated with the number of males that had sung in the predawn male chorus. We suggest that female songs have an intersexual territory defence as well as an intrasexual function.

Acoustic Niches of Siberut Primates

The loud calls nonhuman primates use in long-distance communication have supposedly been selected for efficient information transfer in the habitat. The differential effects of scattering and reverberation and the masking effects of background noise predict that loud calls produced in rain forest habitats should be low-pitched and whistle-like with low-frequency modulation. Callers may also use particular calling posts or times of day with reduced background noise to increase the efficacy of sound transmission. We studied the loud calls of the 4 sympatric primate species on Siberut Island. Only Kloss gibbons (Hylobates klossii) fulfilled the predictions regarding both the structure and use of calls. Though the other 3 species – Mentawai macaques (Macaca siberu), pig-tailed langurs (Simias concolor), and Mentawai leaf monkeys (Presbytis potenziani) – also concentrated their main energies in the spectral window with the lowest background noise, their calls were not adapted to long-range transmission. All 4 species produced loud calls exclusively no lower than 18 m above ground, but food abundance and shelter in the canopy may also be factors. Though all 4 species produced the majority of loud calls in the morning, it was not the only time of day with reduced background noise. We suggest that phylogenetic inheritance may better explain the structure of calls than adaptation to the habitat. In sum, the observed usage of spectral and temporal niches is not solely an adaptation to the sound profile of the habitat, though it clearly improves their transmission.

A Conservation Action Plan for the Mentawai Primates

In this Conservation Action Plan, I evaluate the status of and make conservation recommendations for the four endemic primates of the Mentawai Islands: Kloss's gibbon (Hylobates klossii primates of the Mentawai Islands: Kloss's gibbon (Hylobates klossii primates of the Mentawai Islands: Kloss's gibbon ( ), the simakobu monkey (Simias concolor), the Mentawai langur (Presbytis potenziani langur (Presbytis potenziani langur ( ), and the Mentawai macaque (Macaca pagensis). There are two subspecies of each of the cercopi- thecines. They are threatened mainly by hunting and commercial logging. This action plan follows up on the recommendations made for the Mentawai primates in the IUCN/SSC Primate Specialist Group's Action Plan for Asian Primate Conservation: 1987-91 by Ardith Eudey, and includes data and recommendations from researchers who have studied them since 1980. I also include a brief history of conservation action in the Mentawai Islands to put these recommendations in a historical context. I recommend the following conservation status changes: Kloss's gibbon, Endangered; simakobu monkey, Critically Endangered; Mentawai langur, Endangered; and Mentawai macaque, Vulnerable. The largest populations of the four species can be found in Siberut National Park on the largest and northernmost island, but all but Kloss's gibbon have distinct subspecies on the southern islands of Sipora, North Pagai, and South Pagai, and these are urgently in need of protective measures. The national park is remote and diffi cult to access by researchers and tourists. I suggest the following conservation actions: 1) increased protection for the Siberut National Park, which currently lacks enforcement; 2) formal protection of the Peleonan forest in North Siberut, which is home to unusually high primate populations and is easily accessible; 3) protect areas in the Pagai Islands by cooperating with a logging corporation that has practiced sustainable logging techniques there since 1971; 4) conservation education, especially regarding hunting; and 5) the development of alternative economic models for the local people to reduce the likelihood of selling

Individuality in the Female Songs of Wild Kloss’ Gibbons (Hylobates klossii) on Siberut Island, Indonesia

Observations and recordings were made of the female songs produced by 4 adult and mated female Kloss’ gibbons (Hylobates klossii) from a site on Siberut Island, the largest island of the Mentawai Island chain in Indonesia. A statistical analysis of song characteristics revealed that individuality occurs throughout the entire song. The implications of these findings, as well as comparisons to similar studies of individuality on other gibbon species, are presented.

Human predation and Kloss's gibbon (Hylobates klossii) sleeping trees in Siberut Island, Indonesia.

Kloss's gibbons (Hylobates klossii) and Mentawai langurs (Presbytis potenziani) on Siberut Island, Indonesia, both sleep in emergent trees 34-55m tall, situated on crests and upper slopes of hills. They differ in that 91% of gibbon sleeping trees examined were free of lianas, whereas 89% of langur sleeping trees were draped with thick, woody lianas hanging from the branches to the ground. Because indigenous hunters climb lianas to shoot primates in treetops, gibbons are less susceptible than langurs to nocturnal human predation. Hence, the gibbons' preference for-and apparent control of-the limited supply of vineless trees gives them an advantage over langurs.

Interspecific spacing between gibbons (Hylobates klossii) and langurs (Presbytis potenziani) on Siberut Island, Indonesia.

Spatial arrangement and social interactions of two sympatric and ecologically similar primate species, Hylobates klossii and Presbytis potenzianai, are described from field observations made between July 1972 and October 1974 on Siberut Island, Indonesia. Gibbon territories and langur home ranges overlap extensively. Because gibbons have the ability to supplant langurs at shared food sources, langurs are at a competitive disadvantage. To avoid or decrease the frequency of hostile interactions with gibbons, langurs locate their core areas on boundaries between adjacent gibbon territories, which permits langurs to retreat across these barriers in response to gibbon movements. Langurs further enhance segregration by leaving their sleeping trees earlier than gibbons, gaining additional feeding time on contested food sources. This form of interspecific spatial organization between gibbons and langurs resembles certain predator-prey spacing systems, where territorial boundaries between adjacent predators serve as sanctuaries for prey populations.

Family formation strategies of Kloss's gibbons.

This study describes how adults of Kloss's gibbons (Hylobates klossii) inhabiting the central rain forest of Siberut Island, Indonesia, help their offspring achieve reproductive success. Adults of these monogamous apes exclude maturing offspring from the family and territory through intrasexual aggression. Adults may then assist the offspring to establish a territory contiguous to theirs. Aid may take the form of accompanying offspring into suitable areas not yet occupied or forcefully annexing part of an adjacent territory. Replacement of an adult by its offspring may also occur. A conclusion is that the probability of a young gibbon gaining a territory and mate is greater in the proximity of its parental group than in areas farther afield.

Evolution of long-distance alarm calls in Kloss's gibbon

WE present evidence here that proximity of close kin is a plausible hypothesis to explain the evolution of long-distance alarm calls in Kloss's gibbon (Hylobates klossii). We discovered two alarm calls produced by adults of this monogamous ape that provide good locational cues and are audible for much greater distances than required to signal the immediate family. Our further finding that at least some Kloss's gibbons settle in territories adjacent to their parental families when they mature and establish their own reproductive groups suggests that the adaptive significance of these calls is to warn neighbouring relatives of the presence and location of danger.

Songs, Choruses and Countersinging of Kloss' Gibbons (Hylobates klossii) in Siberut Island, Indonesia

This study evaluates the social spacing mechanism of song as it occurs in Kloss' gibbons. The study population included individuals in 13 family groups whose composition and territories were known (TENZA 1975) plus a number of others. Sonagrams illustrate individual and sexual differences in singing. Sex differences in chorusing, countersinging and other behavior related to song are described. Variations in singing or chorusing or both are related to season, time of day, sex, age, spatial factors and social factors. The adaptive functions of singing, countersinging and chorusing are discussed. It is concluded that: (1) Song is mainly for interterritorial communication between members of the same sex, (2) male-song probably also functions in mate attraction and (3) chorusing is primarily an adaptation reducing predation risk to singing gibbons.