taxonID	type	description	language	source
03D787BA0E38FFC1FFE0FE6FF872CC37.taxon	materials_examined	India, Garo Hills, Assam.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E38FFC1FFE0FE6FF872CC37.taxon	discussion	Genetic studies by L. A. Prouty and colleagues in 1983 recognized the hoolock gibbons as a distinct subgenus, under the name Bunopithecus (originally proposed for a Middle Pleistocene gibbon from Yanjinggou in Sichuan, China). In the taxonomic review of D. Brandon-Jones and coworkers in 2004, hoolock gibbons were listed under the genus Bunopithecus. In 2005, A. Mootnick and C. P. Groves showed that the name Bunopithecus was unavailable and provided a new generic name Hoolock. Mootnick and Groves also argued that leuconedys, formerly considered a subspecies in the eastern distribution of H. hoolock, should be considered a distinct species. Monotypic.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E38FFC1FFE0FE6FF872CC37.taxon	distribution	Distribution. Bangladesh and NE India (states of Assam, Arunachal Pradesh, Nagaland, Meghalaya, Manipur, Mizoram, and Tripura) between the Brahmaputra and Salween rivers, and to the S of the Brahmaputra and E of the Dibang rivers, extending into NW Myanmar, W of the Chindwin River. W. Bleisch has reported an isolated population of gibbons to the N, in the Medog Nature Reserve in SE Xizang Autonomous Region (= Tibet), across the border from Arunachal Pradesh, but their identity has not been established.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E38FFC1FFE0FE6FF872CC37.taxon	description	Descriptive notes. Head-body c. 81 cm; weight 6 - 9 kg (males) and 6 - 1 kg (females). Male and female Western Hoolock Gibbons are comparable in size but quite dissimilar in color. Adult males and juveniles are jet black except for a pair of whitish brow streaks that turn up slightly at the ends; these are quite close together and connected by white hairs. Adult males also have a little white on the chin or under the eyes, and the preputial tuft is black or only faintly grizzled. In contrast, females become copperytan at maturity, with dark brown cheeks and a white face-ring that continues around and under the eyes as suborbital streaks.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E38FFC1FFE0FE6FF872CC37.taxon	biology_ecology	Habitat. Primary tropical rainforest, evergreen and semi-evergreen forests, subtropical broadleaf hill forest, and tropical moist deciduous forest; occasionally in bamboo thickets and plantations of Terminalia myriocarpa (Combretaceae) and Lagerstroemia flos-reginae (Lythraceae). Western Hoolock Gibbons sometimes travel on the ground to reach isolated fruiting trees, especially where their habitats are degraded and fragmented and close to villages where they may make use of cultivated fruit trees. Although they may move through, or sleep in, bamboo forest or plantations, they cannot survive in monocultures. Western Hoolock Gibbons occur at elevations of 500 - 2700 m.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E38FFC1FFE0FE6FF872CC37.taxon	food_feeding	Food and Feeding. The Western Hoolock Gibbon is primarily frugivorous, preferring ripe and fleshy fruits, but they also eat leaves and leaf petioles, flowers and flower buds, seeds, shoots, moss and lichens, insects, spiders, and bird eggs. Regarding the time spent eating different food items; the typical diet is 65 % fruits, 13 % leaves, 12 % petioles, 5 % flowers, and 5 % animal protein. When fruits are scarce, either seasonally or because they are in degraded and fragmented forest patches, they eat more leaves. Figs (Ficus, Moraceae) are particularly important. They feed on bamboo shoots in the Borajan Wildlife Sanctuary, and fruits comprise only 40 % of their diet. Three major studies tallied 464 available plant species in the study areas, of which 88 occurred in the diets of Western Hoolock Gibbons. In north-eastern India, they are an important disperser of seeds for large and small fruit-bearing trees.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E38FFC1FFE0FE6FF872CC37.taxon	breeding	Breeding. Mating of the Western Hoolock Gibbon occurs during the wet season (monsoon) in May-June, and birth peaks occur during the dry season in November — February. Offspring are weaned at about two years old and are considered juvenile until about four years old and subadults between four and six years old. Interbirth intervals are about three years.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E38FFC1FFE0FE6FF872CC37.taxon	activity	Activity patterns. In Bangladesh, Western Hoolock Gibbons spend their days feeding (30 - 8 %), foraging (25 - 8 %), resting (27 - 5 %), and traveling (7 - 4 %), besides calling and engaging in territorial behavior and play. In India, play and grooming activities contribute less than 10 % oftheir daily activities. They rest and play more in the longer days of summer. Gibbons are active for 8 - 10 hours, starting at dawn or in the early morning, waking earlier in summer than winter. Pairs of Western Hoolock Gibbons call in the morning before leaving their sleeping sites on most but not all days and sometimes in the afternoon before retiring. They alternate their calls as a “ double solo ” rather than producing duets. Feeding dominates the morning hours and rest in the early afternoon. Activity ends usually several hours before sunset, possibly to avoid competing with other primates at their feeding trees. Preferred sleeping sites are emergenttrees, often those infested with epiphytes; mid-canopy trees are less preferred. A female and her infant sleep together, generally with the adult male; older offspring sleep separately.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E38FFC1FFE0FE6FF872CC37.taxon	biology_ecology	Movements, Home range and Social organization. Western Hoolock Gibbons live in family groups of 2 - 6 individuals (usually about three), consisting of an adult pair, juveniles, and infants. Females dominate males. In Bangladesh, their home ranges are 8 - 63 ha, while home ranges in India can be 200 - 400 ha, probably based on the size of the habitat fragments. They travel 300 - 1800 m / day. Scarcer food and more widely dispersed food sources are probably the reason for larger home ranges in India.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E38FFC1FFE0FE6FF872CC37.taxon	conservation	Status and Conservation. CITES Appendix I. Classified as Endangered on The IUCN Red List. The Western Hoolock Gibbon is legally protected in Bangladesh, India, and Myanmar. It is threatened by habitat loss and hunting for food and traditional Asian medicine. In Bangladesh, there is an estimated population of only 300 individuals in highly fragmented pockets of suitable habitat, while in north-eastern India, there are 2200 - 2600 individuals. More than 50 % of the Western Hoolock Gibbons in India is in isolated, small, and unsustainable subpopulations, often ofjust one or two groups. Across India and Bangladesh, habitat quality is rapidly declining, even where the forest is left standing; they suffer the loss of their preferred food trees and adequate sleeping sites, and the remaining forest structure and the broken canopy do not allow for brachiation. The degradation and destruction of their forest habitats results from the collection of firewood, timber extraction, plantations for the pulp industry, invasion of exotic plant species, crop cultivation, erosion, and disturbance of undergrowth, road construction, and urbanization. Unplanned intensive tourism, hunting, army training, natural gas extraction, slash-and-burn agriculture (“ jhum ” cultivation), and intensive commercial agriculture, such as tea plantations, comprise major threats. Commercial and subsistence hunting for food by hill tribes is particularly severe in Nagaland in far north-eastern India. Even when not hunted, people compete for food and cut down preferred fruit trees for timber, degrading the remaining forest patches. Namdapha National Park in the Changlang district of Arunachal Pradesh has the largest contiguous stretch of protected forest in India and is a stronghold for the Western Hoolock Gibbon. They also occur in Lawachara National Park and Chunati and West Bhanugach wildlife sanctuaries in Bangladesh and Balphakram, Nokrek, Namdapha, Dibru-Saikhowa, Intanki, Kaziranga, and Murlen national parks and Bherjan, Borajan, Dampa, Garampani, Hoollongapar Gibbon, Gumti, Kamlang, Khawnglung, Nengpui, Nongkhyllem, Phawangpui, Sepahijala, Siju, and Trishna wildlife sanctuaries in India.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E38FFC2FAE6F83EFD7BC2BB.taxon	materials_examined	Burma (= Myanmar), Sumprabum, 1200 m.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E38FFC2FAE6F83EFD7BC2BB.taxon	discussion	Previously considered a subspecies of H. hoolock, but now treated as a full species. It is separated from H. hoolock by the Chindwin River, although intermediates may occur in the headwaters. Monotypic.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E38FFC2FAE6F83EFD7BC2BB.taxon	distribution	Distribution. NE India, marginally in the states of Arunachal Pradesh (Lohit and Lower Dibang Valley districts) and Assam (Tinsukia District), E Myanmar (E of the Chindwin River), and S China in W Yunnan Province.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E38FFC2FAE6F83EFD7BC2BB.taxon	description	Descriptive notes. Head-body 45 - 65 cm; weight 6 - 9 kg. In a mixed sex sample from China, the average weight was 7 - 2 kg (n = 5). The Eastern Hoolock Gibbon is distinguished from the Western Hoolock Gibbon (H. hoolock) by its white preputial tuft, the complete separation of the white eyebrows, a lighter silvery chest, and generally white hairs under the eyes and on the chin in the black phase. Hands of females may be lighter in color than the body.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E38FFC2FAE6F83EFD7BC2BB.taxon	biology_ecology	Habitat. Closed-canopy, lowland, broadleaved evergreen forest; lowland, semi-evergreen, and mixed deciduous forests and higher elevation evergreen and semi-evergreen forests. Elevational records of the Eastern Hoolock Gibbon are 1600 - 2600 m in China, 142 - 1865 m in India, and up to ¢. 2300 m in Myanmar.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E38FFC2FAE6F83EFD7BC2BB.taxon	food_feeding	Food and Feeding. There is no specific information for this species, but its diet and feeding behavior are probably similar to those of the Western Hoolock Gibbon.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E38FFC2FAE6F83EFD7BC2BB.taxon	breeding	Breeding. First menstruation occurred in one female Eastern Hoolock Gibbon at about seven years of age.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E38FFC2FAE6F83EFD7BC2BB.taxon	activity	Activity patterns. The Eastern Hoolock Gibbon is diurnal and arboreal. No behavioral studies have been published on Eastern Hoolock Gibbons, but they are probably similar in their behavior to Western Hoolock Gibbons. In India, Eastern Hoolock Gibbons call between 07: 00 h and 12: 00 h, and singing bouts last 5 - 35 minutes and average 18 minutes.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E38FFC2FAE6F83EFD7BC2BB.taxon	biology_ecology	Movements, Home range and Social organization. The Eastern Hoolock Gibbon is presumably territorial, although no specific data exist. Mean group size has been recorded in a number of population surveys; 3 - 9 individuals (n = 9) in China, three individuals (n = 7) in Mahamyaing Wildlife Sanctuary, and 3 - 1 individuals (n = 28) in Mehao Wildlife Sanctuary, India. Two of nine groups observed in China had more than one adult female. Population density estimates from 17 spot surveys in Myanmar averaged 2 - 6 groups / km?. Densities from one well-studied site in Mahamyaing Wildlife Sanctuary, Myanmar, were 0 - 71 - 5 - 1 groups / km? in eleven sampled areas and averaged 2: 2 groups / km? * or 8 - 9 ind / km ®. At the time of this survey, densities seemed to be unaffected by recent selective logging at this site.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E38FFC2FAE6F83EFD7BC2BB.taxon	conservation	Status and Conservation. CITES Appendix I. Classified as Vulnerable on The IUCN Red List. The Eastern Hoolock Gibbon is legally protected in Myanmar, China, and India. Threats to the Myanmar population include hunting, especially in northern areas near the Chinese border, and habitat degradation and fragmentation. Some sites that maintain populations of Eastern Hoolock Gibbons apparently have no major threats. Since 1984, 56 locality records have been verified in Myanmar. Less than 200 individuals are now believed to persist in China, restricted to only three counties and fragmented into 17 subpopulations, the largest of which has only five groups. The population in Gaoligongshan National Nature Reserve, China, appears to be relatively secure, although it is small and therefore vulnerable. The Chinese population is declining, with nine recorded local extinctions in the past two decades and five subpopulations now having only one remaining group, suggesting their imminent demise. Local extinctions have been caused by logging operations, hunting, agricultural encroachment for cardamom cultivation, and shifting agriculture. Hunting of Eastern Hoolock Gibbons was very high in the past, but in some areas, local communities do not hunt them (although they do hunt other primates), which is at least partially responsible for their persistence. The population of Eastern Hoolock Gibbons in India is restricted to a small area in the north-east, with an estimated 3000 individuals, including c. 157 groups in Mehao Wildlife Sanctuary. Populations in India are probably declining, with habitat destruction and hunting being the major threats. Habitat conversion for cultivation (including cardamom), habitat fragmentation, and slash-and-burn agriculture are threats in Mehao. The most significant populations occur in Myanmar, with a recent national status review suggesting a population of 290,000 - 370,000 individuals, based on density estimates from 17 spot surveys and an estimate of 42,500 km? of remaining habitat suitable for Eastern Hoolock Gibbons. Nevertheless, these estimates may have significant bias, because the areas surveyed were in localities known to have gibbons, sample size was small, and estimates of forest cover were problematic. Regardless, it is clear that Myanmar holds the vast majority of Eastern Hoolock Gibbons, with the Kachin Northern Forest Complex and Southern Kachin-Northern Sagaing forests estimated to hold the majority of the national and therefore global population. The best-documented population is in Mahamyaing Wildlife Sanctuary, which had an estimated 1051 - 2468 groups or 3500 - 8100 individuals in 2004. Overall, the Eastern Hoolock Gibbon occurs in at least eight protected areas including Gaoligongshan National Nature Reserve in China; Mehao and Kamlang wildlife sanctuaries in India; and Mahamyaing, Phongun Razi, Htamanthi, and Indawgyi Lake wildlife sanctuaries, and Panlaung-Padah-Lin Caves Reserved Forest in Myanmar. Additional populations in the headwaters on the Chindwin River including Hukawng Valley Wildlife Sanctuary and Hukawng Valley Tiger Reserve (an extension), Myanmar, are of unknown taxonomic affinity, existing in the transition zone between Eastern and Western hoolock gibbons.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3BFFC2FF38F57CF885C07F.taxon	materials_examined	Indonesia, West Sumatra.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3BFFC2FF38F57CF885C07F.taxon	discussion	Some experts recognize two subspecies: agilis to the west and wunko to the east. In the Barisan Range of Sumatra, the pale morph is more common, while in the eastern lowlands and on the Malay Peninsula, the black morph predominates. Genetic data, however, do not support a division into subspecies. There is a small area of sympatry between this species and H. lar in northern Peninsular Malaysia, where both also hybridize, having been trapped on the “ wrong ” side of Lake Mudah when it was created by a hydroelectric dam in the late 1970 s. It is sympatric with S. syndactylus in Sumatra. Monotypic.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3BFFC2FF38F57CF885C07F.taxon	distribution	Distribution. S Thailand (near the Malaysian border, E of the Thepha River watershed), N Peninsular Malaysia (from the Mudah and Thepha rivers in the N to the Perak and Kelantan rivers in the S), and most of Sumatra (from SE of Lake Toba and the Singkil River to the S).	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3BFFC2FF38F57CF885C07F.taxon	description	Descriptive notes. There are no specific body measurements available; weight 5.7 - 5 kg (males) and 4.5 - 7.3 kg (females). The Agile Gibbon is sometimes called the darkhanded gibbon because its hands and feet are colored the same as the body or are somewhat darker. It is extremely variable in color, but it is not sexually dichromatic. Its coat may be either black (or maroon-brown) or pale (buff, gray, or creamy, with a darker ventral surface), and both sexes sport a white brow band. Adult males and juveniles have light (white or russet-white) cheek whiskers and a partial beard; females lose this at maturity. The crown hairis directed fanwise from the front of the scalp and is somewhat elongated over the ears.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3BFFC2FF38F57CF885C07F.taxon	biology_ecology	Habitat. Semi-deciduous monsoon and tropical evergreen forest up to 1400 m above sea level. The Agile Gibbon is found at its highest densities in dipterocarp-dominated forest, but it also occurs in swamp and lowland forest to hill, submontane, and montane forest. It prefers the middle and upper canopy.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3BFFC2FF38F57CF885C07F.taxon	food_feeding	Food and Feeding. The Agile Gibbon is frugivorous, preferring fruits high in sugar, but it also eats immature leaves and insects — 60 % fruit, 39 % young leaves, and 1 % animal matter.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3BFFC2FF38F57CF885C07F.taxon	breeding	Breeding. Parental care by Agile Gibbons is predominantly given by the mother, although the father and elder siblings also assist. Weaning takes place at 18 months. Juveniles of both sexes reach adult size at aboutsix years of age, but they remain with their natal group until they reach sexual maturity at ¢. 8 - 9 years. Individuals may live more than 30 years.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3BFFC2FF38F57CF885C07F.taxon	activity	Activity patterns. Agile Gibbons are diurnal and arboreal, with much feeding and traveling early in the day. Both activities decline steadily throughout the day, and they settle for the night well before dusk.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3BFFC2FF38F57CF885C07F.taxon	biology_ecology	Movements, Home range and Social organization. Average home range size was 29 ha for Agile Gibbons at Sungai Dal (Gunung Bubu Forest Reserve) on Peninsular Malaysia, with mean daily movements of 1339 m. Males are mainly responsible for defending the group’s territory from external threats such as humans. Females lead group's daily progressions and keep away other females, thereby preventing males from having more than one mate. Density estimates vary by population: 1 - 4 - 2 - 8 ind / km? in Bukit Barisan Seletan National Park, Sumatra; 6 - 11 - 4 ind / km? in Kerinci-Seblat National Park, Sumatra; and 5 - 5 - 18 - 9 ind / km ® (2 - 5 groups / km?) in Sungai Dal. A density of 2 groups / km? * was estimated in parts of Hala Bala Wildlife Sanctuary, Thailand.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3BFFC2FF38F57CF885C07F.taxon	conservation	Status and Conservation. CITES Appendix I. Classified as Endangered on The IUCN Red List. The Agile Gibbon is protected by law in Indonesia, Malaysia, and Thailand. It is threatened mainly by loss of habitat due to logging, fires, spread of plantations (coffee, rubber, and other crops), and the illegal pet trade. It is especially threatened in the Sumatran part ofits distribution where it seems to be declining rapidly. On the mainland (Peninsular Malaysia and Thailand), there seem to be a number of stable populations, but their distributions have contracted. The Agile Gibbon is entirely confined to closed-canopy forest, and habitat conversion, road building, and fragmentation are increasing threats. It occurs in twelve protected areas: Batang Gadis, Berbak, Bukit Barisan Selatan, Bukit Duabelas, Bukit Tigapuluh, Kerinci-Seblat, Sembilang, Tesso Nilo, and Way Kambas national parks in Sumatra, Indonesia; Gunung Bubu, Belum-Temenggor, and Ulu Mudah forest reserves in Malaysia; and Hala Bala Wildlife Sanctuary in Thailand. Unfortunately, many of these protected areas are merely proposed, and their status is uncertain. Moreover, many of the Sumatran parks are in montane regions where Agile Gibbons only occur at low densities. In Bukit Barisan Selatan National Park in south-western Sumatra, populations are presently secure and healthy, but their continued survival depends on the Indonesian government regaining control over illegal deforestation in its parks. A population estimate over the whole range of the Agile Gibbon does not exist, but a 2002 assessment in Bukit Barisan Selatan calculated a population of 4479 individuals. In Peninsular Malaysia, Belum-Temenggor and Ulu Mudah are strongholds. The population of Agile Gibbons in Thailand likely numbers only a few thousand individuals, located in about three forest fragments or reserves.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3BFFC3FA3EF4E5FD22C32D.taxon	materials_examined	Indonesia, near Sukadana, south-west Borneo.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3BFFC3FA3EF4E5FD22C32D.taxon	discussion	Previously regarded as a subspecies of H. agilis. This species hybridizes with H. muelleri and H. abbotti in a wide area of central Borneo. Monotypic.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3BFFC3FA3EF4E5FD22C32D.taxon	distribution	Distribution. SW Borneo (West Kalimantan & Central Kalimantan provinces), S of the Kapuas River and W of the Barito River.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3BFFC3FA3EF4E5FD22C32D.taxon	description	Descriptive notes. There are no specific body measurements available; weight 4.9 - 6 kg (males) and 6.1 - 6.8 kg (females). The Bornean White-bearded Gibbon is similar to the Agile Gibbon (H. agilis), but with no black morph. Of all the gibbons, this species has the most colorful and distinctive coat pattern. It is light grayish-brown, becoming golden-toned on the rump and with a blackened ventral zone, hands, and feet. The crown hair is directed fanwise from the front of the scalp, and the cap is dark although margined with buff. Males often have a light genital tuft.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3BFFC3FA3EF4E5FD22C32D.taxon	biology_ecology	Habitat. Primary, secondary, and selectively logged tropical evergreen forest up to 1200 m above sea level and peat-swamp forest. Population densities decrease at higher elevations.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3BFFC3FA3EF4E5FD22C32D.taxon	food_feeding	Food and Feeding. The Bornean White-bearded Gibbon is predominantly frugivorous, preferring fruits high in sugar, butit also eats immature leaves and insects.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3BFFC3FA3EF4E5FD22C32D.taxon	breeding	Breeding. Full maturity of male and female Bornean White-bearded Gibbons occurs at 6 - 8 years of age.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3BFFC3FA3EF4E5FD22C32D.taxon	activity	Activity patterns. The Bornean White-bearded Gibbon is diurnal and arboreal. In Sabangau National Park, Central Kalimantan, they spend, on average, 29 % their day feeding, 29 % traveling, 29 % resting, 9 % in singing, and 4 % engaged in social activities.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3BFFC3FA3EF4E5FD22C32D.taxon	biology_ecology	Movements, Home range and Social organization. Polygynous pairings have been reported in the H. albibarbis x H. muelleri (Miller's Gibbon) hybrid zone. Average home range sizes were 28 ha and 47 ha for Bornean White-bearded Gibbons in Gunung Palung and Sabangau national parks, respectively. In general, males are aggressive toward other males and also defend their group's territory. Females usually lead the group's daily progressions and keep away other females. Population densities range from 7 - 4 ind / km? (2 - 2 groups / km?) in logged peatswamp forest of Sabangau National Park and 8 - 7 ind / km? in primarily heath forest in Tanjung Puting National Park, Central Kalimantan, to 14 - 9 ind / km? in mountain forests in Gunung Palung National Park, West Kalimantan.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3BFFC3FA3EF4E5FD22C32D.taxon	conservation	Status and Conservation. CITES Appendix I. Classified as Endangered on The IUCN Red List. The Bornean White-bearded Gibbon is legally protected in Indonesia. It is threatened mainly by habitat loss due to fires, illegal logging, and oil palm plantations. A'large part ofits distribution occurs in peat swamp — an extremely threatened ecosystem because of draining, logging, and burning. The Bornean White-bearded Gibbon was certainly affected by the widespread forest fires in the 1990 s and continuing deforestation, but no recent surveys are available on population trends. The Bornean Whitebearded Gibbon is frequently captured for pets and occasionally hunted for meat. It occurs in six protected areas: Bukit Baka Bukit Raya, Gunung Palung, Tanjung Puting, and Sabangau national parks and Hampapak and Kendawangan nature reserves in Indonesia. The Bornean White-bearded Gibbon is generally common in suitable habitat. A tentative estimate suggests that ¢. 19,000 individuals live in the mixed-swamp forest subtype in Sabangau National Park, which has one of the largest remaining continuous populations. An estimate of the total population is not available.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3AFFC3FFE5F732F651C728.taxon	materials_examined	Indonesia, West Sumatra, South Pagai Island.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3AFFC3FFE5F732F651C728.taxon	discussion	Little to no geographic variation has been observed among populations on differ ent Mentawai islands. In a very small sample of specimens, some variation in the direction of the hair on the forearm was observed. Genetic and vocal data suggest that no differentiation has occurred between the islands, likely due to historic gene flow as recently as 7000 years ago. Monotypic.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3AFFC3FFE5F732F651C728.taxon	distribution	Distribution. Endemic to the MentawaiIs off the W coast of Sumatra (Siberut, Sipura, North Pagai, South Pagai, and Sinakakislet off the E coast of South Pagai).	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3AFFC3FFE5F732F651C728.taxon	description	Descriptive notes. Head-body 43.5 - 58.5 cm (males) and 42 - 58 cm (females); weight 5.7 - 8 kg (males) and 4.4 - 6.8 kg (females). Female Kloss’s Gibbonsare slightly smaller than males, but they have canine teeth that are similar in size. Kloss’s Gibbon is considered one of the smallest gibbons, although its body size is within the range observed in other species of Hylobates. Both sexes and all ages have completely black fur with no markings. Kloss’s Gibbon was originally described as a “ dwarf siamang ” due to its black fur, but morphologically it more closely resembles other species of Hylobates than the Siamang (Symphalangus syndactylus). One notable difference is that the fur is sparser than is typical of other species of Hylobates, and there is a nearly bare area on the throat. In some respects, the skull of the Kloss’s Gibbon also resembles that of the Siamang.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3AFFC3FFE5F732F651C728.taxon	biology_ecology	Habitat. Primary semi-deciduous monsoon and tropical evergreen forest at all elevations. Kloss’s Gibbons generally prefer to remain in the upper canopy. They have also been observed in swamp forest. Mentawai forests are ever-wet, with annual rainfall of up to 4000 mm. Throughoutits distribution, Kloss’s Gibbon is sympatric with the Pigtailed Langur (Simias concolor), and the Siberut Langur (Presbytis siberu) and the Siberut Macaque (Macaca siberu) on Siberut and the Mentawai Langur (P. potenziani) and the Pagai Macaque (Macaca pagensis) on the southern Mentawai Islands.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3AFFC3FFE5F732F651C728.taxon	food_feeding	Food and Feeding. Kloss’s Gibbons are predominantly frugivorous. Fruits make up c. 73 % of their feeding time, arthropods and other small animals ¢. 25 % (their primary source of protein), and leaves c. 2 % (less than is typical of other gibbons). Kloss’s Gibbon is dominant to the Siberut and Mentawai surelis, always displacing them from food trees when they meet.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3AFFC3FFE5F732F651C728.taxon	breeding	Breeding. Kloss’s Gibbon appears to breed throughout the year. Single births are the norm. Age classification is the same as for other gibbons: infants up to two years old are dependent on the mother; juveniles, age 2 — 4 years, are independent; adolescents, age 4 - 6 years, display increased aggression toward same-sex parents; the subadult stage begins when about six years old; and adult independence is typically achieved at about eight years old. Adult males do not carry offspring. Individuals may live more than 30 years.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3AFFC3FFE5F732F651C728.taxon	activity	Activity patterns. Kloss’s Gibbons are diurnal and arboreal. Groups spend much of their day at rest. They do not use the same sleeping tree two nights in a row and choose sleeping sites that do not have biting ants. They also prefer sleeping trees that lack hanging lianas, which may be an adaptation to avoid human predation because Mentawai hunters often climb lianas to shoot primates. Unlike most other gibbons, Kloss’s Gibbons do not sing duets. Instead, adult males sing from sleeping trees in the hours before dawn, sometimesas early as 01: 00 h. Adult females typically chorus after the first feeding bout of the day (07: 00 - 09: 00 h). Singing appears to be contagious, and male bouts typically occur in “ countersinging ” interactions, in which adjacent individuals take turns singing and avoid overlapping. Neighboring females may produce songs in synchrony. The greatcall of the female Kloss’s Gibbon has been described as “ the finest music uttered by any land mammal, ” and itis often accompanied by an acrobatic display. Females exhibit structural individuality in their songs, such that each female can be distinguished by their song alone. The male’s song is simpler than the female’s. As in other gibbons, the primary function of the female's song is to defend the territory and possibly to advertise mated status. Solitary, “ floating ” male Kloss’s Gibbons that do not occupy a territory have been observed to sing, suggesting that mate attraction may be a function of the male’s song.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3AFFC3FFE5F732F651C728.taxon	biology_ecology	Movements, Home range and Social organization. Home ranges of Kloss’s Gibbons are 7 - 32 ha, probably varying in relation to habitat quality and floristic composition. Average daily movement is 1514 m. Group size is typically 4 - 6 individuals. Groups as large as 10 - 15 individuals have been observed on North Pagai and Siberut, butit is unclearif these are stable units. In general, males are aggressive toward other males and defend their territories from predators (humans), while females tend to lead group’s movements during the day, and also exclude other adult females from the group. At about eight years old, Kloss’s Gibbons find a mate and establish their own territory. Young adult Kloss’s Gibbons may establish territories adjacent to their parents’ territories, with their parents’ assistance. They may also replace a deceased same-sex adult in their parental territory to live with the remaining opposite-sex adult; in the observed cases, it was not known whether that surviving adult was the genetic parent of the young adult. Disturbance levels in the habitats of Kloss’s Gibbons vary on the different islands, but recent surveys have detected similar densities in unlogged forests, forests logged ten years ago, and those logged 20 years ago. The highest densities have been observed in northern Siberut. Density in the Mentawai islands averages 12 ind / km?,	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3AFFC3FFE5F732F651C728.taxon	conservation	Status and Conservation. CITES Appendix I. Classified as Endangered on The IUCN Red List. Kloss’s Gibbon is protected under Indonesian law, but it occurs in only one protected area, Siberut National Park. The total population, based on limited survey effort using auditory sampling, is 20,000 - 25,000 individuals, with island totals of 18,210 - 21,345 for Siberut, 753 - 880 for Sipora, and 1680 - 1974 on North and South Pagai together (another estimate for these last two islands, using a transect-based approach, was 2029 individuals). The vast majority of the global population is believed to be in Siberut National Park, with 13,190 - 15,413 individuals, but this estimate is based on a survey of less than 0 - 1 % of the park and therefore needs to be viewed as preliminary. Total population decline of Kloss’s Gibbon may be ¢. 50 % since 1980. Threats include hunting, commercial logging, forest conversion for agroindustry, especially oil palm, and forest clearance and disturbance at the local scale. Selective logging is widespread across the distribution of Kloss’s Gibbon, but one study suggests that this may have limited impact on carrying capacity. Hunting pressure has been exacerbated by increased access to forested areas through logging infrastructure and a move away from traditional hunting methods in the use of guns. Infant Kloss’s Gibbons are often taken as pets by hunters after they kill a parent. Traded Kloss’s Gibbons mostly remain in the Mentawai islands but sometimes go to neighboring western Sumatra. Increased legal protection of the remaining populations, including those in the Peleonan Forest, increased commitment and planning for conservation from logging companies, and improved enforcement in Siberut National Park are key conservation interventions.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3AFFC5FADAF331F6ECC94C.taxon	materials_examined	Restricted by C. Kloss in 1929 to Malaysia, Malacca.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3AFFC5FADAF331F6ECC94C.taxon	discussion	The various subspecies are not highly distinct and are based largely on relatively minor body color variation and the degree of polychromatism in the fur. The validity of yunnanensis as a distinct taxon is doubtful, and it is probably synonymous with carpenter. Some publicationsstill consider yunnanensis a valid subspecies, but this may be moot because populations of the taxon are probably extinct. This species forms a narrow zone of sympatry and hybridization with H. pileatus in Khao Yai National Park, central Thailand, and with H. agilis in the Malay Peninsula (human-induced by the creation of a lake in the 1970 s), and it is broadly sympatric with Symphalangus syndactylusin the Malay Peninsula and north Sumatra. Five subspecies are recognized.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3AFFC5FADAF331F6ECC94C.taxon	distribution	Subspecies and Distribution. H. l. larLinnaeus, 1771 — MalayPeninsula, from 9 ° NtotheMudahRiverandSofthePerakRiver. H. l. carpenteriGroves, 1968 — EMyanmar, NWLaos, andNWThailand, fromChiengDaoat 19 ° 22 ° Nto ¢. 16 ° N. H .. entelloides 1. GeoffroySaint-Hilaire, 1842 — SMyanmarandSWThailand, fromc. 15 ° No 10 ° N. H. l. vestitusG. S. Miller, 1942 — NSumatra, NWofLakeTobaandtheSingkilRiver. H. l. yunnanensis Ma & Wang, 1986 — S China (SW Yunnan Province), the northernmost subspecies, originally between the Nujiang (= Salween) and Lancangjiang (= Mekong) rivers in the counties of Cangyuan, Menglian, and Ximeng; by the 1960 s limited to the Nangun River at elevations of 1000 - 1500 m, but now probably extinct there.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3AFFC5FADAF331F6ECC94C.taxon	description	Descriptive notes. Head-body 41 - 4 cm (males) and 41 - 6 cm (females); weight 4.1 - 7.3 kg (males, n = 43) and 3.9 - 6.1 kg (females, n = 37). These measurements and weights are taken from publications by A. Schultz in 1933 and 1973; weights are from the type series of the “ Carpenter’s Lar Gibbon ” (H. Ll carpenteri) and may include some immature animals. Measurements from southern China “ Yunnan Lar Gibbon ” (H. I. yunnanensis) were provided by S. Ma and colleagues in 1988: mean head-body length of four males and a female 49 - 9 cm (range 44.5 - 57.8 cm) and mean weight 7 - 2 kg (range 5.3 - 8.5 kg). In 1929, C. Kloss provided weights of the “ Sumatran Lar Gibbon ” (H. I. vestitus): males 4.3 - 5.5 kg and a female 5 - 3 kg. The Lar Gibbon has two main color phases — dark (brown to black) and pale (creamy-fawn to reddish-buff) — that have no relation to age or gender, although the exact shading may vary by region. In museum collections, specimens of the Sumatran Lar Gibbon are fairly light brown (like the pale phase of the “ Central Lar Gibbon, ” H. l. entelloides), and it would seem that the Sumatran Lar Gibbon does not show color polymorphism, but this needs to be confirmed in the wild populations. All Lar Gibbons have a naked black face encircled by a ring of whitish fur, with sharply contrasting white fur on uppersides of hands and feet. The crown hair is directed fanwise from the front of the scalp and is not elongated or laterally projected over the ears. Adult males have black tufted fur on the pubic region. Sexes are similar in size. Color is very variable in the Malay Peninsula (from dark brown to buff), but further north, individuals are either very dark (black) or very pale (creamy-fawn) with no intermediates; these extremes are not related to sex, unlike neighboring species of hoolock and crested gibbons.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3AFFC5FADAF331F6ECC94C.taxon	biology_ecology	Habitat. Lowland to dipterocarp forests; mixed deciduous bamboo forests; evergreen, semi-evergreen, and wet evergreen forests; and even peat-swamp forests, mainly below 1200 m above sea level. The Lar Gibbon prefers the upper canopy of undisturbed primary forests, but it also occurs in secondary and selectively logged forests. Average height of feeding trees of Lar Gibbons in Khao Yai National Park, Thailand, is 23 - 7 m.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3AFFC5FADAF331F6ECC94C.taxon	food_feeding	Food and Feeding. Lar Gibbons feed on a large variety of foods. Figs and other small, sweet fruits are preferred, but young leaves, buds, flowers, new shoots, berries, vines, vine shoots, insects (including mantids and wasps), and bird eggs are also consumed. They are known to eat parts of more than 100 species of plants. Diet varies considerably with seasons; for example, in Khao Yai National Park, non-fig fruits dominate the diet throughout the year except in November-December. There, flowers are most available during the cool season, while ripe fruit is most abundant during the hot-wet seasons. Ripe fruit is preferred when available, with the diet being more diversified when ripe fruit is less available during the cool season. Fruit (including figs) never falls below 50 % of the diet year-round. Overall, the average diet is composed of 66 % fruit, 24 % leaves, 9 % insects, and 1 % flowers. Lar Gibbons compete with sympatric Siamangs (Symphalangus syndactylus), the presence of which usually causes conflict and probably reduces the foraging success of Lar Gibbons. Food competition may also take place between Lar Gibbons and the Sunda Pig-tailed Macaque (Macaca nemestrina), because the two species have been seen foraging near one another and will sometimes interact, and also with Long-tailed Macaques (M. fascicularis) and Dusky Langurs (7 Trachypithecus obscurus).	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3AFFC5FADAF331F6ECC94C.taxon	breeding	Breeding. The Lar Gibbon has a menstrual cycle of 21 - 2 - 22 days (range 15 - 25 days). In the wild, females reproduce for the first time when about eleven years old (range 9 years and nine months to twelve years and nine months). At a minimum, the interbirth interval is three years and averages 3 - 4 years. If a female loses a baby, she may ovulate again sooner, but the average interbirth interval in a population at carrying capacity is c. 3 - 5 years. Females exhibit swelling, protrusion, and a change in the color of the sexskin beginning several days before ovulation and ending after ovulation, usually lasting c. 7 - 11 days. Pregnant females also show sexual swelling at random times during pregnancy. Females start to show a conspicuous swelling of the vulva by the third month of pregnancy. Mating occurs in every month of the year, but most conceptions occur during the dry season (March). Sexual solicitation by the female involves her placing herself in front of a male and looking back at him, presenting her genitals. Copulation is dorso-ventral, with the male behind the female. Females may refuse copulation by moving away from the male, calling, or agonistically refusing his advances. Male-male mounting has been observed among wild male Lar Gibbons. Gestation is about six months in the wild. There are few observations of births and infant development of Lar Gibbons. At one studysite in Thailand, births showed a peak during the late wet season to early dry season transition in September — - October. Neonates weigh an average of 383 - 4 g and are almost entirely naked except for a cap of fur on the crown. They are able to call soon after birth. Parental care is given predominantly by the mother, although the father and eldersiblings also assist. In the wild, infants are carried clinging to their mother’s ventrum. Observations of one infant in the wild and of captive Lar Gibbons show that solid food is first ingested at four months of age. The wild infant also starts moving a short distance from its mother at that age. The ability to brachiate was first seen in a captive infant around nine months old. Infants are weaned at about 28 months old. Infant mortality is generally low, less than 10 % in the first year oflife. Juveniles of both sexes reach adult size at aboutsix years of age, but they remain with their natal group until they reach sexual maturity at around 8 - 9 years. Generation length of Lar Gibbonsis c. 15 years. They mature late, with females maturing at 8 - 10 years and males at 8 - 12 years, and have one offspring every 3 - 5 years. These data were obtained from a site, however, with a density of Lar Gibbons high enough to suspect that maturity was being delayed — perhaps a case of “ saturated ” habitat. They live for at least 40 years in the wild, but as long as 50 years in captivity.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3AFFC5FADAF331F6ECC94C.taxon	activity	Activity patterns. Lar Gibbons are diurnal and arboreal. On average, they spend their day feeding (33 %), resting (26 %), traveling (24 %), engaged in social activities (11 %), vocalizing (4 %), and involved in intergroup encounters (2 %), although actual proportions of activities can change significantly over the course of the year. Much of the day is spent foraging and resting. Lar Gibbons in Thailand are active for an average of 8 - 7 hours / day, leaving their sleeping sites around sunrise and entering sleeping trees an average of 3 - 4 hours before sunset. If the morning is clear before dawn, an adult male emits his solo calls, usually from his sleeping tree. At sunrise when all members of a group awaken, they defecate and urinate while hanging from a branch. The group then movesto a feeding tree. There is normally a duet call among the adult pair before noon, and the rest of the day is spent alternating between feeding and traveling to new trees to feed. With seasonal reductions in the amount of available fruit, feeding time increases and correspondingly less time is spent in social activities. The group usually pauses each day for about an hour of rest and social activities. Lar Gibbonstry to avoid notice when moving to sleeping sites, possibly as a way of reducing predation. Often the tallest trees available are chosen as sleeping sites, if possible located on steep slopes or cliffs. During the cool season, groups of Lar Gibbons can often be found in large fig trees for up to several hours a day.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3AFFC5FADAF331F6ECC94C.taxon	biology_ecology	Movements, Home range and Social organization. As a rule, Lar Gibbons live in serial monogamous pairs with up to four offspring in each group, but occasionally they are found in socially polyandrous groups (a female and two adult males); sometimes sexual relationships can extend beyond the mated pair (extrapair copulations), and polygamous mating has also been observed. Long-term data indicate that females may live in several different types of groups (e. g. pair or multimale) over their lifetimes. In the case of extrapair copulation by females, however, the frequency of copulation remains much higher with the pair-mate than with other males. Censuses at Khao Yai National Park from 1992 to 2007 recorded an average proportion of pairs of 76 - 9 % (n = 120), with multimale — unifemale (polyandrous) groups accounting for 21 -: 2 % (n = 33, groups with mature male offspring excluded). Unimale-multifemale groups are rare (1: 9 %), and in the single case recorded in Khao Yai, one of the females was a Pileated Gibbon (H. pileatus) and not a Lar Gibbon. In the case of individual pair-bonds, changes can result from desertion (often for another mate), replacement of one of a pair by a peripheral individual, or disappearance or death of one of the adults. Changes in pair composition can be common due to disease, shortage of food resources, and fragmented and isolated forests. Pair bonds are normally life-long. Average group size in Lar Gibbons generally increases with latitude, illustrating that group size is not a useful species-specific character in gibbons. This reflects a general trend of increasing birth rate with latitude found in many vertebrate groups. Average group sizes have been reported at 2 - 7 - 3 - 3 individuals in Peninsular Malaysia, 3 - 7 in central Thailand, and 4 - 4 — 4 - 9 in northern Thailand. Home ranges are 12 - 54 ha, averaging c. 40 ha, with highs of 44 - 54 ha on the Malay Peninsula and c. 16 ha in Khao Yai National Park. While home ranges of different groups often overlap, sometimes extensively, there is a core territory defended from other groups that averages 76 % of the home range. Average daily movementis 1400 m, although there is considerable variation among study sites. Daily movements tend to increase with greater fruit availability. Group progressions at some locations are usually led by an adult male, while at other sites females lead and coordinate group movements. Males are mainly responsible for defending the group’s territory. Within-group social behavioris variable throughout the year, from almost a fifth of the activity budget to only a small percentage; there is more social activity at times when ripe fruit is abundant. The three main types of within-group social interaction are grooming, play (wrestling, chasing, and slapping and biting), and social contact, with grooming being the most common. Aggression is rare. In general, immature Lar Gibbons play more than adults. There are some indications that allogrooming serves more of a hygienic than a social function in Lar Gibbons and tends to be reciprocal. Encounters between different groups of Lar Gibbons can range from agonistic (physical altercations) to friendly (between-group playing or grooming). Most interactions between groups are agonistic, but they can be purely vocal and even neutral (both groups when they meet barely react to one another). Groups may also travel, feed, or rest together when they come into contact. Males are the principal participants in most territorial disputes, but females are sometimes approached by males during intergroup interactions. Disputes generally occur near boundaries of the home range when two groups can see each other. They typically last about an hour, and most intergroup interactions are accompanied by calls. Variability of the nature of interactions between neighboring groups may partly be the result of variable social and kin relationships between members. Nevertheless, intergroup interactions can be quite violent, and there is evidence that wounds incurred in territorial aggression have resulted in death. There is seasonal variation in the occurrence of intergroup encounters, and territoriality may function in resource defense. In one long-term study, males dispersed from their natal groups at about ten years of age and usually attained a territory by replacing a resident adult. Dispersal distances are usually c. 1 - 2 territories from the natal territory, averaging 0 - 71 km in one population. Densities of Lar Gibbons range from 2 - 4 groups / km? in Ketambe Research Station, Gunung Leuser National Park, Sumatra, to 0 - 7 - 2 - 6 groups / km? in Kuala Lompat and Tanjong Triang on the Malayan Peninsula and 6 - 5 groups / km? in Khao Yai National Park.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3AFFC5FADAF331F6ECC94C.taxon	conservation	Status and Conservation. CITES Appendix I. Classified as Endangered on The IUCN Red Lust. The status of each subspecies of Lar Gibbon is: lar, vestitus, and carpenter are Endangered, entelloides is Vulnerable, and yunnanensis is Data Deficient. The Yunnan Lar Gibbon has been declared extinct in China, but it may still survive in Myanmar. The major threats to Lar Gibbons are loss of habitat and hunting. They are hunted for subsistence and for the pet trade. Hunting pressure varies across the range, but they are hunted even within protected areas. They are traditionally hunted by hill tribes in Thailand, and increased forest fragmentation has increased hunting pressure there. In Sumatra, some local people have a religious taboo against hunting primates, including Lar Gibbons, but in some areas, taboos against hunting gibbons appear to be breaking down. Shifting agriculture and commercial plantations of oil palm are major causes of deforestation. Some protected areas (e. g. Nam Phouy Biodiversity Conservation Area in Laos) are threatened with road construction within their boundaries. This promotes forest clearing and strip development and increases fragmentation and access by hunters. In northern Sumatra, most of the lowland forests have been logged, and the threat of Ladia Galaska, a road network to link the west and east coasts of Aceh Province, means that much of the remaining forest is at risk. In most of its range, the Lar Gibbon is confined to protected areas (e. g. in Thailand, no significant populations survive outside them), but, in most countries, these areas are not well patrolled, even if they are well managed for tourism. Illegal use of forest products and poaching are common in most protected areas. In Thailand, the decrease in forest cover has caused increased hunting. Further survey work is needed to determine current population numbers in protected areas. Current estimates suggest that there are probably 15,000 - 20,000 Lar Gibbons in Thailand with several populations numbering in the thousands, although they are now very rare in the north. The largest Thailand population is in Kaeng Krachan National Park with 3000 - 4000 individuals; the Western Forest Complex may well have 10,000 individuals; there may be more than 1000 individuals in the western part of Khao Yai National Park, as well as in Phu Khieo Wildlife Sanctuary and Nam Nao National Park. A few smaller populations survive in the south (e. g. Khao Sok National Park). In southern Peninsular Thailand and north-western Peninsular Malaysia, a few smaller, fragmented populations survive, perhaps together numbering in the low thousands. There are no recent or reliable estimates of the populations in the Tenasserim section of Myanmar, northern Sumatra, or the southern Peninsular Malaysia. There are also no reliable estimates for Laos, but there may be a few hundred Lar Gibbons in Nam Phouy Biodiversity Conservation Area. The nominate subspecies lar occurs in at least two protected areas: Krau Wildlife Reserve in Malaysia and Thale Ban National Park in Thailand. The Sumatran Lar Gibbon occurs in Gunung Leuser National Park in Indonesia. The Central Lar Gibbon occurs in Maegatha and Kaser Doo wildlife sanctuaries and Tanintharyi National Park in Myanmar; Kaeng Krachan, Khao Yai, and Khao Sok national parks and Thung Yai Naresuan and Huai Kha Khaeng wildlife sanctuaries in Thailand. This is probably the least threatened subspecies because ofits relatively extensive distribution and presence in the largest forest areas now in numerous parks and wildlife sanctuaries. Hunting pressure, however, isstill a problem in most areas, making it vulnerable to ongoing declines. West of the Mekong River in Laos, Carpenter’s Lar Gibbon persists in small forest patches in Nam Phouy Biodiversity Conservation Area, but it is hunted there. In Laos, populations outside Nam Phouy are small, isolated, and hunted, and nationally Carpenter’s Lar Gibbon is critically endangered. It also occurs in Nam Nao National Park and Phu Khieo and Huai Kha Khaeng wildlife sanctuaries in northern Thailand. The Yunnan Lar Gibbon was, until 1992, known to have occurred in just one protected area, Nan’gunhe National Nature Reserve in south-western Yunnan, China. Much of the forest in the Nan’gunhe is now degraded and secondary, inappropriate for Lar Gibbons, or has been converted directly to farmland. Surveys in search of this subspecies were carried out in 2008, and it was concluded that it had been entirely extirpated as a result of continued forest destruction, fragmentation, and deterioration and hunting. It is not known to occur anywhere else, but slim hope remains that there are populations in neighboring Myanmar.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3CFFC5FAE3FDD8F8ADC6E8.taxon	materials_examined	Indonesia, Java. Restricted by H. Sody in 1949 to WJava, Mt. Salak.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3CFFC5FAE3FDD8F8ADC6E8.taxon	discussion	Although it has been suggested that there is evidence for two genetically distinct populations leading to the subsequent recognition of two subspecies by some authors, a review of the molecular evidence and a comparison of morphological and vocal data casts doubt on this claim. The central Javan form, pongoalsoni, said to be characterized by a black cap, may be a distinct subspecies, or it may simply be a morph, because black caps may also occur in western Java. Monotypic.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3CFFC5FAE3FDD8F8ADC6E8.taxon	distribution	Distribution. Java, mainly in W provinces (Banten and West Java), with an additional population in a small area in the C as far E as the Dieng Mts.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3CFFC5FAE3FDD8F8ADC6E8.taxon	description	Descriptive notes. There are no specific body measurements available; weight 6 - 6 kg (males) and 6 - 2 kg (females). Fur of the Moloch Gibbon is very long and uniformlysilvery-gray. It has a blackish face and at least a trace of black on the cap and chest. There is a poorly expressed light face-ring and a short white beard on the chin, and eyebrows are pronounced. The crown hairis directed fanwise from the front of the scalp and is somewhat elongated over the ears. The teeth are notably larger than in other species, with large cingula, unreduced third molars and, frequently, supernumerary cusps. The silvery gray color, the relatively large teeth, and its calls (non-duetting with simple note repetition) are consistent differences that distinguish it from other gibbons.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3CFFC5FAE3FDD8F8ADC6E8.taxon	biology_ecology	Habitat. Primary lowland and lower montane rainforest up to 2400 m above sea level (but normally below 1600 m). Moloch Gibbons prefer floristically rich patches of relatively undisturbed forest, but they can tolerate moderate disturbance.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3CFFC5FAE3FDD8F8ADC6E8.taxon	food_feeding	Food and Feeding. Diets of Moloch Gibbons consist mainly offruits (61 %) and leaves (38 %), and they eat some flowers and insects.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3CFFC5FAE3FDD8F8ADC6E8.taxon	breeding	Breeding. Interbirth intervals of Moloch Gibbons are typically 3 - 3 - 5 years, and sexual maturity of males and females occurs at 8 - 10 years of age. Age at first reproduction may be 10 - 12 years. Infants are creamy with a slight hint of a facial ring and a pink face, and the natal coat darkens rapidly to adult coloration. A female Moloch Gibbon lived to 50 years of age at the Winnipeg Zoo, Canada.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3CFFC5FAE3FDD8F8ADC6E8.taxon	activity	Activity patterns. There is no specific information available for this species, but it is diurnal and arboreal.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3CFFC5FAE3FDD8F8ADC6E8.taxon	biology_ecology	Movements, Home range and Social organization. Home ranges of Moloch Gibbons are 17 - 60 ha, most of which is defended. In general, males are aggressive toward other males and also defend their territory from external threats. Females lead the group’s daily progressions and keep away other females. It is believed that Moloch Gibbons, like Kloss’s Gibbons (H. klossii), do not duet, but more detailed studies are needed to confirm this. Median densities are 2 - 7 groups / km? or 9 ind / km? in lowland forest (below 500 m above sea level), 2: 6 groups / km? * or 8: 6 ind / km? in hill forest (500 — 1000 m), and 0 - 6 groups / km? or 1 - 5 ind / km? in low montane forest (1000 - 1750 m).	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3CFFC5FAE3FDD8F8ADC6E8.taxon	conservation	Status and Conservation. CITES Appendix I. Classified as Endangered on The IUCN Red List. Moloch Gibbons live on one of the world’s most densely populated islands, and they have been severely affected by loss of habitat. Despite protection by law since 1924, numbers of Moloch Gibbons have continued to slide to perilously low levels. Historical deforestation that affected Java in colonial times still maintains an overriding presence on the landscape, effectively restricting the arboreal Moloch Gibbon to continuous tracts of forest around mountain and volcano tops. Habitat disturbance today is relatively low, and populations, while isolated, appear to have stabilized. Wildlife trade exerts an as yet unknown effect on the Moloch Gibbon. It occurs in more than 15 locations, of which nine are protected: Gunung Gede Pangrango, Gunung Halimun, and Ujung Kulon national parks, Gunung Papandayan, Gunung Kedeng, and Gunung Slamet protection forests, and Gunung Tilu, Gunung Simpang, and Telaga Warna protected areas. These gibbons are also found in the Situ Gunung Tourist Park, which offers some degree of protection. The second largest population in the Dieng Mountains is unprotected. More than 95 % of the Moloch Gibbons are in populations of more than 100 individuals, and the four largest areas support more than 500 each. In 2002, the wild population was estimated at 4000 - 4500, and in 2008 at less than 2500 mature individuals.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3FFFC6FA32FCCDF5B5C12B.taxon	materials_examined	Indonesia, Pontianak, south-western Borneo.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3FFFC6FA32FCCDF5B5C12B.taxon	discussion	Until recently, H. abbotti was considered a subspecies of H. muelleri, but morphologically and genetically it is distinct as a species. It hybridizes with H. albibarbis in central Borneo. A population .. in east-central Kalimantan may prove, with further research, to be a morph or a distinct subspecies. There are wide intergrade zones between H. abbotti, H. funereus, and H. muelleri where their ranges meet. Monotypic.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3FFFC6FA32FCCDF5B5C12B.taxon	distribution	Distribution. SW Borneo (S Sarawak State & West Kalimantan Province), N of the Kapuas River and as far E as the Spaoh (= Saribas), District of Sarawak.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3FFFC6FA32FCCDF5B5C12B.taxon	description	Descriptive notes. There are no specific body measurements available; weight 5.9 - 6.4 kg (males) and 5.5 - 6 kg (females). Abbott’s Gray Gibbon is medium gray; the ventrum and crown are a little darker. Hands and feet are not darkened. The crown hair is directed fanwise from the front of the scalp and is markedly elongated over the ears.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3FFFC6FA32FCCDF5B5C12B.taxon	biology_ecology	Habitat. Primary and secondary semi-deciduous monsoon, dipterocarp, and tropical evergreen forest. Abbott’s Gray Gibbon is tolerant of selective logging to some extent if sufficient tall, fruit-bearing trees are retained.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3FFFC6FA32FCCDF5B5C12B.taxon	food_feeding	Food and Feeding. Its diet undoubtedly includes young leaves, fruits, and flowers and insects, but this species has not been studied in the wild.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3FFFC6FA32FCCDF5B5C12B.taxon	breeding	Breeding. There is no information available for this species.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3FFFC6FA32FCCDF5B5C12B.taxon	activity	Activity patterns. Abbott's Gray Gibbon is diurnal and arboreal.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3FFFC6FA32FCCDF5B5C12B.taxon	biology_ecology	Movements, Home range and Social organization. There is no specific information available for this species, but it is probably very similar in these aspects to Muller's Gibbon (H. mueller).	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3FFFC6FA32FCCDF5B5C12B.taxon	conservation	Status and Conservation. CITES Appendix I. Classified as Endangered on The IUCN Red List (as H. mueller: abbotti). Abbott's Gray Gibbon is protected under Indonesian and Malaysian law. As for other gibbons on Borneo, logging, hunting, and deforestation are the main threats. It occurs in five protected areas: Betung-Kerihun and Danau Sentarum national parks in West Kalimantan (Indonesia) and Batang Ai and Bako national parks and Lanjak Entimau Wildlife Sanctuary in Sarawak (Malaysia). The population of Abbott’s Gray Gibbon is not known, but the “ gray gibbons ” (Miiller’s, East Bornean Gray, H. funereus, and Abbott's Gray gibbons) in Borneo have been estimated at 250,000 - 375,000 individuals.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3FFFC6FF3EFEB9F7B4C864.taxon	materials_examined	Indonesia, Kalimantan. Restricted by M.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3FFFC6FF3EFEB9F7B4C864.taxon	discussion	Lyon in 1911 to south-eastern Borneo. Until recently, H. funereus and H. abbotti were recognized as subspecies of H. muelleri, but morphologically and genetically they are clearly distinct species. H. mueller: hybridizes with H. albibarbis in the upper Barito watershed in central Borneo. This hybridization is evidently old (5000 - 10,000 years), and the hybrid zone covers about 5000 km?, which for some is argument that H. albibarbis and H. mueller should be considered conspecific. A population living in east-central Kalimantan may prove to be a morph or a distinct subspecies. There are wide intergrade zones between H. mueller, H. funereus, and H. abbotti where their ranges meet. Monotypic.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3FFFC6FF3EFEB9F7B4C864.taxon	distribution	Distribution. Borneo, SE Kalimantan, approximately S of the Mahakam River and E of the Barito River.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3FFFC6FF3EFEB9F7B4C864.taxon	description	Descriptive notes. Head-body 40 - 8 cm; weight 5.6 - 8 kg (males) and 4.6 - 6.2 kg (females). The pelage of Miller's Gibbon is either mouse-gray or brownish in color. These gibbons have a dark cap, face, and chest which varies in extent individually and with age, becoming more extensive in older individuals. Males differ from females by having a pale, often incomplete, facial fringe and a dark brown (as opposed to black) crown. The crown hair is directed fanwise from the front of the scalp and is markedly elongated over the ears.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3FFFC6FF3EFEB9F7B4C864.taxon	biology_ecology	Habitat. Primary and secondary semi-deciduous monsoon, dipterocarp, and tropical evergreen forest. Miller's Gibbons can tolerate a degree of selective logging if sufficient tall, fruit-bearing trees remain. Hybrid H. mueller: x H. albibarbis (Bornean Whitebearded Gibbon) have been studied by K. McConkey at Barito Ulu, in the Barito River watershed, Central Kalimantan, where the terrain is described as rugged (hilly to mountainous). There, dipterocarp forest predominates, interspersed with heath forest. The dry season is from July to September and the wet season is between October and January, with a mean annual rainfall of 3738 mm.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3FFFC6FF3EFEB9F7B4C864.taxon	food_feeding	Food and Feeding. The study in Barito Ulu focused on the composition of the diet, and aspects of seasonality, food selection, and seed dispersal. Over a year, non-fig fruits were the most common items eaten, followed by young leaves, and figs and flowers; only very small numbers of insects were recorded. The diet in terms of these plant parts varied during the year. Fig trees can fruit throughout the year and figs were eaten according to their availability. Other fruits were more predictably seasonal. Fruits were available year round, but peaked in abundance and diversity in March-May. Flowers peaked in abundance in January-February and again in September, and the gibbons evidently favored them. Flowers were the strongest predictor of what the gibbons would eat in a given month. When they were abundant, they would increase their visits to flowering trees and reduce the time spent eating fruit. Overall the diet of two groups during one year was 62 % fruit (52 - 7 % ripe fruit and 9 - 3 % unripe fruit and seeds), 23 - 8 % young leaves, 13 - 4 % flowers, and 0 - 8 % insects. In all, 54 - 7 % of the fruits were of trees, 27 - 3 % were from lianas, 17 - 3 % were figs, and 0 - 7 % were from parasites and epiphytes. Fruits were taken from c. 167 species. An analysis of selection ratios for different fruit types showed that they preferred medium-size (6 - 30 g), yellow-orange fruits with a juicy pulp and a thin or rind-like skin, in dense but small crops. They avoided purple-black and red fruits with softdry pulp, many-seeded fruits in sparse crops, and fruits with large seeds (more than 20 mm wide). They did not eat fruit with seeds larger than 40 mm in width. They were most selective when they could afford to be, when fruits were abundant. Fruits of Gnetum microcarpum (Gnetaceae) and Cryptocarya crassinervia (Lauraceae), Erycibe maingayi (Convolvulaceae), and Diospyros puncticulosa (Ebeneaceae) were found to be important when fruit was scarce. The gibbons dispersed seeds by endozoochory (ingestion and defecation) of 81 % of the fruits (90 % of the liana species, 72 % of the tree species) that they ate (others were unripe, destroyed, or dropped). More than 90 % of the seeds were defecated more than 100 m from the parent tree (the mean was more than 300 m and the maximum was 1000 m), and feces (and seeds) were scattered as they fell to the forest floor — aspects considered favorable for the seeds.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3FFFC6FF3EFEB9F7B4C864.taxon	breeding	Breeding. There is no specific information available for this species, but aspects of breeding will be very similar to the East Bornean Gray Gibbon (H. funereus).	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3FFFC6FF3EFEB9F7B4C864.taxon	activity	Activity patterns. Miiller’s Gibbons are diurnal and arboreal.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3FFFC6FF3EFEB9F7B4C864.taxon	biology_ecology	Movements, Home range and Social organization. Two groups studied at Barito Ulu comprised a single adult pair with a subadult and a juvenile or infant. They occupied home ranges of 43 ha and 46 ha. About 88 % of the home range is defended as a territory for the exclusive use of the resident group. Although generally monogamous, polygynous pairings have been reported in the H. muelleri x H. albibarbis hybrid zone. Other aspects of their social organization and ranging are probably very similar to the East Bornean Gray Gibbon for which some information is available from the study of D. Leighton at Kutai National Park.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3FFFC6FF3EFEB9F7B4C864.taxon	conservation	Status and Conservation. CITES Appendix I. Classified as Endangered on The IUCN Red List (as H. m. mueller). Miiller’s Gibbons are protected under Indonesian law and occur in three protected areas: Sultan Adam Forest Park (South Kalimantan Province), Kersik Luwai National, and Sungai Wain Protection Forest Park (both in East Kalimantan Province). This speciesis generally common. Deforestation (most recently for oil palm plantations), logging, hunting, and trade in illegal pets are the principal threats. The population density in Sungai Wain Protection Forest was estimated at 7 - 9 - 9 - 5 ind / km? A population estimate for Miiller’s Gibbon does not exist, but the population of “ gray gibbons ” (Miiller’s, East Bornean Gray, and Abbott's Gray, H. abbotti, gibbons) has been estimated at 250,000 - 375,000.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3FFFC7FA3AF531FEA8C1BB.taxon	materials_examined	Philippines, Sulu Islands.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3FFFC7FA3AF531FEA8C1BB.taxon	discussion	The type locality is obviously in error, which may have arisen because Sabah was formerly part of the Sultanate of Sulu. Until recently, H. funereus was considered a subspecies of H. mueller, but morphologically and genetically it is a distinct species. There are wide intergrade zones between H. funereus, H. muelleri, and H. abbotti where their ranges meet. Monotypic.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3FFFC7FA3AF531FEA8C1BB.taxon	distribution	Distribution. N & NE Borneo, from Sabah State S to the Mahakam River in East Kalimantan Province and perhaps W to the Baram District and the IV Division of Sarawak State.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3FFFC7FA3AF531FEA8C1BB.taxon	description	Descriptive notes. Head — body 48 - 5 cm (males, n = 3) and 47.5 - 49 cm (females, n = 3); weight 5.6 - 4 kg. Pelage of the East Bornean Gray Gibbon is very dark brown or gray. Hands and feet are not darker than limbs and are sometimes lighter. The crown hair is directed fanwise from the front of the scalp and is markedly elongated over the ears.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3FFFC7FA3AF531FEA8C1BB.taxon	biology_ecology	Habitat. Primary and secondary semi-deciduous monsoon, dipterocarp, and tropical evergreen forest. They are found to about 1700 m above sea level in Sabah, but densities decrease at higher elevations. East Bornean Gray Gibbons have been studied by D. Leighton in Kutai National Park, East Kalimantan, north of the Mahakam River. The forest there is largely lowland dipterocarp (much ofit logged) but also includes tropical moist heath forest (“ keranga ”) on sandy acidic soils and, in the coastal area, mangroves. These gibbons can tolerate a degree of selective logging provided that sufficient tall, fruit-bearing trees are left standing.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3FFFC7FA3AF531FEA8C1BB.taxon	food_feeding	Food and Feeding. The composition of the diet recorded over a year at Kutai was as follows: fruit 62 % (monthly variation 27 - 90 %); leaves 32 % (8 - 73 %); flowers 4 % (0 - 6 %); and insects 2 % (0 - 6 %). As for all gibbons, figs (Ficus, Moraceae) are important, averaging 24 % ofthe fruit part of the diet.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3FFFC7FA3AF531FEA8C1BB.taxon	breeding	Breeding. Breeding is not seasonal. Generally it is the male that initiates mating. Parental care is given predominantly by the mother, although the father and elder siblings assist, and the male spends more time than the female playing with and grooming the young. Juveniles of both sexes reach adult size at around six years old, but remain with their natal group until they reach sexual maturity at around 8 - 9 years. The birth interval is 36 months. Individuals can live up to 47 years.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3FFFC7FA3AF531FEA8C1BB.taxon	activity	Activity patterns. East Bornean Gray Gibbons travel and forage in the upper middle and upper canopy, 25 - 30 m above the ground. They sleep, rest, and sing in the canopies of emergent trees. They are active for 8 - 10 hours per day, usually starting at dawn but resting and retiring in the mid- to late afternoon well before sunset. Singing and feeding are most intense in the morning hours.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3FFFC7FA3AF531FEA8C1BB.taxon	biology_ecology	Movements, Home range and Social organization. At Kutai, seven family groups of East Bornean Gray Gibbons averaged 3 - 4 individuals; an adult male, adult female, and their offspring. The average home range size of four groups was found to be 36 ha (range 33 - 43 ha). The day range of the groups at Kutai averaged 800 m (350 - 1890 m). They use the ranges unevenly, but will generally visit all parts of it over a few days. They do not habitually patrol the range, but the simulation of an intrusion using playback does result in some monitoring of the range borders. Females initiate duets and lead joint approaches to playbacks of female solos, whereas males lead silent, joint approaches to playbacks of male solos. In general, males are aggressive toward other males and defend their territory, while females lead the group’s daily progressions and are aggressive toward other females. Females tend to be more aggressive than males, and are dominant over them. The female grooms the male much less frequently than vice versa. The male is the more aggressive during intergroup encounters. Densities, estimated using various techniques, range from 9 - 14 - 6 ind / km? at Kutai National Park to 6 - 9 - 9 - 9 ind / km * at Kayang Mentarang National Park.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3FFFC7FA3AF531FEA8C1BB.taxon	conservation	Status and Conservation. CITES Appendix I. Classified as Endangered on The IUCN Red List (as H. mueller: funereus). The East Bornean Gray Gibbon is protected under Indonesian and Malaysian law. It is generally common where good forest remains, although logging activities have rendered the range patchy. The widespread fires in the El Nino years in the 1980 s and 1990 s devastated forests over a large part ofits range. Much of its habitat was also lost in colonial times and is being further impacted by oil palm plantations and logging activities. Deforestation, trade in illegal pets, and hunting are the predominant threats. East Bornean Gray Gibbons occur in the following protected areas: Kutai and Kayan Mentarang national parks in East Kalimantan (Indonesia); Tawau Hills, Kinabalu, and Crocker Range national parks in Sabah (Malaysia); Pulong Tau, Gunung Mulu, and Gunug Buda national parks in Sarawak (Malaysia); and Ulu Temburong National Park in Brunei. There is no population estimate for the East Bornean Gray Gibbon, but “ gray gibbons ” (Muller's, H. muelleri, East Bornean Gray, and Abbott's Gray, H. abbotti, gibbons) have been estimated at 250,000 - 375,000 individuals.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3EFFC7FFE0F4A0F71BC0A2.taxon	materials_examined	Cambodia.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3EFFC7FFE0F4A0F71BC0A2.taxon	discussion	Based on reports beginning in 1925, the Pileated Gibbon forms a narrow hybrid zone with H. lar in Khao Yai National Park, central Thailand, specifically, in the headwaters of the Takhong-Mun-Mekong river system. Monotypic.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3EFFC7FFE0F4A0F71BC0A2.taxon	distribution	Distribution. SE Thailand (E & S of the Mun and Takhong rivers, W limit may have formerly been the Bang Pakong River), SW Laos (W of the Mekong River), and N & W Cambodia (W of the Mekong River); the species may have formerly occurred in S Vietnam.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3EFFC7FFE0F4A0F71BC0A2.taxon	description	Descriptive notes. No specific measurements are available. Male and female Pileated Gibbons are very different in their pelage color. Adult males are almost completely black except for a whitish border surrounding their face (sometimes just a brow band or a pair of long grayish fringes along each temple). Males have white hands and feet (some earlier researchers mistakenly classify them as a separate form) and a white pubic tuft. Females and juveniles are silvery-gray or fawn-buff with black on the crown cap, cheeks, and chest (spreading down the inner surfaces of limbs with age), and a white face-ring. The crown hair is directed fanwise from the front of the scalp.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3EFFC7FFE0F4A0F71BC0A2.taxon	biology_ecology	Habitat. Moist, seasonal evergreen and mixed deciduous-evergreen forests up to elevations of 1200 m in Thailand and up to 1500 m in Cambodia. They prefer mid- and high canopies.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3EFFC7FFE0F4A0F71BC0A2.taxon	food_feeding	Food and Feeding. The Pileated Gibbon is similar to the Lar Gibbon (H. lar) in diet and general ecology, consuming mostly fruits (71 %), flowers (15 %), young shoots (2 %), and some immature leaves and insects.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3EFFC7FFE0F4A0F71BC0A2.taxon	breeding	Breeding. Infant Pileated Gibbons are cream-colored until about the end of their first year when the coat becomes silvery-buff until puberty. At this point, malesstart to take on their very different adult coloration. Full maturity occurs at 6 - 8 years in both males and females. Individuals may live up to 39 years.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3EFFC7FFE0F4A0F71BC0A2.taxon	activity	Activity patterns. The Pileated Gibbons is diurnal and arboreal. Groups spend much of their day at rest. They sleep an average of almost 16 hours / day, rising at dawn and concluding their activities until about mid-afternoon (12: 45 - 15: 50 h). The Pileated Gibbon is somewhat shyer and more elusive than the Lar Gibbon.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3EFFC7FFE0F4A0F71BC0A2.taxon	biology_ecology	Movements, Home range and Social organization. Pileated Gibbons are largely monogamous, but polygynous pairings have been reported in the hybrid zone at Khao Yai National Park, Thailand. Home ranges are 15 - 50 ha. Males are mainly responsible for defending the group’s territory and leading its daily progressions. Mixed groups of the Lar and Pileated gibbons with two adult females have been reported in Thailand. The average group size in Thailand is four individuals. Densities are generally low in Thailand, averaging close to 1 group / km? or 4 ind / km?, with pockets of higher density in some remote mountain areas. In the Cardamom Mountains of Cambodia, densities are 1 - 2 groups / km? ®. No density figures are available for Laos.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E3EFFC7FFE0F4A0F71BC0A2.taxon	conservation	Status and Conservation. CITES Appendix I. Classified as Endangered on The IUCN Red List. The Pileated Gibbon is threatened by continued loss of habitat due to fragmentation and degradation, with many populations isolated in small pockets of montane forest. It is occasionally hunted for food. Many populations in Cambodia do not occur in protected areas and suffer from habitat loss due to logging, agriculture, hydroelectric development, and new human settlements. These are major threats, especially in remote areas. In Thailand, all remaining populations are now in protected areas, but subsistence hunting by minor forest-product collectors is still uncontrolled. The Pileated Gibbon occurs in 25 protected areas: Beng Per Wildlife Sanctuary, Preah Monivong (= Bokor), Botum Sakor, and Kirirom national parks, Preah Vihear and Central Cardamom Mountains protection forests, and Kulen Promtep, Phnom Aural, and Phnom Samkos wildlife sanctuaries in Cambodia and Phu Chong-Na Yoi, Namtok Phliu, Khao Chamo-Khao Wong, Khao Khitchakut, Khao Yai, Pang Sida, Thab Lan, and Ta Phraya national parks and Khao Ang Rue Nai, Dong Yai, Huai Sala, Phanom Dong Rak, Yot Dom, Khlong Khrua Wai, and Khao Soi Dao wildlife sanctuaries in Thailand. In 2005, it was estimated that there were more than 35,000 individuals in Cambodia and 13,000 - 14,000 in Thailand. In Cambodia, the most important area for Pileated Gibbons is the Cardamom Mountains, with an estimated 20,000. In Thailand, an estimated 12,000 survive in four principal protected areas (Khao Yai, Thab Lan, Khao Ang Rue Nai, Khao Soi Dao), while another 1000 - 2000 occur in 15 other highly fragmented protected areas. Numbers for Laos are unknown, but they are believed to be significantly lower due to their limited range in the country.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E30FFC9FF04FE00F8D6CD09.taxon	materials_examined	Vietnam, Tonkin.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E30FFC9FF04FE00F8D6CD09.taxon	discussion	Up to four subspecies have been recognized. Here, the two forms named by S. Ma and Y. Wang in 1986 (furvogaster from south-western Yunnan west of the Mekong River and jingdonensis found in westcentral Yunnan, China) are considered synonymous with the nominate from, concolor, based on recent genetic evidence. Two subspecies are recognized.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E30FFC9FF04FE00F8D6CD09.taxon	distribution	Subspecies and Distribution. N. ¢ c. concolor Harlan, 1826 — S China (C & SW Yunnan Province) including a small population W of the Mekong River near the Myanmar border, and N Vietnam (Lao Cai, Son La, and Yen Bai provinces) between the Black and Red rivers from ¢. 20 ° N 023 ° 45 ° N. c. c. lu Delacour, 1951 — NW Laos (Bokeo and Luang Namtha provinces) in an isolated population E of the Mekong River at ¢. 20 ° 17 ° N- 20 ° 25 ’ N.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E30FFC9FF04FE00F8D6CD09.taxon	description	Descriptive notes. Head-body 43 - 45 cm; weight 7 - 8 kg. In 1988, Ma and colleagues provided the following measurements: mean head-body of four males and five females, 49 - 5 cm (range 43 - 54 cm) and mean weight 7 - 8 kg (range 6.9 - 10 kg). As with other species of Nomascus, the Western Black Crested Gibbon is sexually dichromatic; males are completely black with a pronounced crown crest and females are pale yellow through beige brown, often with a darker ventral area that may contrast sharply, and a black cap. Infants are born buff and transition to the same pelage as adult males, which they maintain as juveniles and subadults. Males maintain this pelage color to adulthood, but females change to their adult pelage color as they reach maturity.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E30FFC9FF04FE00F8D6CD09.taxon	biology_ecology	Habitat. Semi-humid, montane broadleaf evergreen forest in high elevation subtropical areas. The Western Black Crested Gibbon has been recorded at ¢. 500 - 2900 m above sea level.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E30FFC9FF04FE00F8D6CD09.taxon	food_feeding	Food and Feeding. The Western Black Crested Gibbon probably inhabits an extreme of the hylobatid ecological niche, occupying high elevational seasonal forests. Diet reflects this, with high levels of leaf consumption and low levels of fruit intake compared with other gibbons. Relative frequencies of consumption of food types have been recorded as 46 - 5 % leaves, 25 - 5 % fruit, 18: 6 % figs, 9 - 1 % flowers, and 0 - 3 % other. High levels of folivory were also recorded in earlier studies, and indeed the Western Black Crested Gibbon has been characterized as a folivore-frugivore. Diet changes markedly throughout the year depending on fruit and fig availability. It has been recorded hunting and feeding on giant flying squirrels (Petaurista philippensis) on Mount Wuliang in China. This was the first record of such behavior in gibbons — now also confirmed for the Northern Yellow-cheeked Crested Gibbon (N. annamensis). The same group of Western Black Crested Gibbons preys on chicks, eggs, and lizards, and passive food sharing of meat has also been documented.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E30FFC9FF04FE00F8D6CD09.taxon	breeding	Breeding. There is no information available for this species.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E30FFC9FF04FE00F8D6CD09.taxon	activity	Activity patterns. The Western Black Crested Gibbon is diurnal and arboreal. Activity begins just before dawn; often commences with loud vocalizations. Feeding peaks in mid-morning and mid-afternoon, with a rest period in the middle of the day. Weather affects activity, and during cold periods, the Western Black Crested Gibbon decreases travel and rests more. Likewise, fruit availability has been implicated in affecting activity patterns, with periods of high fruit consumption linked to longer travel times to visit this seasonal and sparsely distributed resource. Relative frequencies of behavioral categories have been recorded as 40 % resting, 35 - 1 % feeding, 19 - 9 % traveling, 2: 6 % singing, 1 - 2 % playing, and 1 - 2 % other.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E30FFC9FF04FE00F8D6CD09.taxon	biology_ecology	Movements, Home range and Social organization. The social organization of the Western Black Crested Gibbon has long been disputed, with early research suggesting it formed polygynous groups — contested by later researchers. Recent studies on five focal groups in China showed, however, that all occurred in single male-two female groups and that in three of them, both females were breeding; other groups in the area had only a single female. In Vietnam, groups with more than one female are also common. Polygynous groups appearstable in structure, and female antagonism toward other females is rare. This social structure possibly allows groups to more effectively defend their territories, which are large compared with other gibbons. Estimates of home range size vary considerably at 40 - 151 ha. Large territories may be due to the highly seasonal nature of the forests they occupy. While territories are large, daily movements are similar to other published findings for gibbons. Daily travel distances were variable in one group studied, with a range of 300 - 3144 m and an average of 1391 m. Monthly distances traveled are correlated with fruit and leaf abundance; daily distances moved are shorter in months with low fruit availability, presumably an energy conservation strategy.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E30FFC9FF04FE00F8D6CD09.taxon	conservation	Status and Conservation. CITES Appendix I. Classified as Critically Endangered on The IUCN Red List, along with both subspecies. The Western Black Crested Gibbon is legally protected in China, Vietnam, and Laos. It is known to occur in at least ten protected areas: Wuliangshan, Ailaoshan, Fengshuiling, Huanglianshan, Yongde Daxueshan, and Nanggunhe national nature reserves in China; Mu Cang Chai Species and Habitat Conservation Area and Hoang Lien-Van Ban Nature Reserve in Vietnam; and Nam Ha and Nam Kan biodiversity conservation areas in Laos. China holds the vast majority of the remaining population of the “ Tonkin Black Crested Gibbon ” (N. ¢. concolor). In Yunnan Province its numbers are estimated at 1100 - 1300 in more than 270 groups. The largest populations are in the parallel chains of the Wuliang and Ailao mountains, with estimates of 87 groups in Wuliangshan National Nature Reserve and more than 150 groups in Ailaoshan National Nature Reserve. In Vietnam, the Tonkin Black Crested Gibbon occurs in two protected areas: Mu Cang Chai Species and Habitat Conservation Area in Yen Bai Province and adjacent forest in Muong La, Son La Province, and Hoang Lien-Van Ban Nature Reserve in Lao Cai Province. The population in Vietnam numbers only 64 - 70 individuals in 22 - 25 groups, with ¢. 20 groups in Mu Cang Chai / Muong La area and only 2 - 5 groups in Van Ban. These populations have been monitored since 2001 and have declined despite conservation interventions. Only the population in Mu Cang Chai / Muong La may be viable, but it is severely threatened by hunting and road and dam construction. The “ Laotian Black Crested Gibbon ” (N. ¢. lu) is restricted to two protected areas in north-western Laos: Nam Ha and Nam Kan. The population in Nam Ha has been almost extirpated, while that in Nam Kan has only 9 - 14 groups and receives some protection through an ecotourism project. Hunting and infrastructure development, specifically the building of Road No. 3 through Nam Kan, pose significant threats. Additional undiscovered populations of the Western Black Crested Gibbon may still exist in the north-western and central parts of the northern highlands of Laos.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E30FFCAFAF8F966FECCC3B8.taxon	materials_examined	Vietnam, Along (= Ha Long) Bay.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E30FFCAFAF8F966FECCC3B8.taxon	discussion	Based on vocal and genetic evidence, N. nasutus is now differentiated from N. concolor and N. hainanus, to which it is most closely related. Monotypic.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E30FFCAFAF8F966FECCC3B8.taxon	distribution	Distribution. Restricted to a small area along the Sino-Viethamese border in Trung Khanh District (Cao Bang Province, NE Vietnam) and Jingxi County (Guangxi Province, SE China); the historical distribution stretched from SE China to N Vietnam as far S and W as the Red River.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E30FFCAFAF8F966FECCC3B8.taxon	description	Descriptive notes. No specific measurements are available, but the Eastern Black Crested Gibbon is similar in size to other species of Nomascus. As with those species of gibbons, the Eastern Black Crested Gibbon is sexually dichromatic. Males are predominantly black, with a brown tinge on the chest, and females are yellow to beige brown. Females have a wide, white face-ring, and a long, black crown-streak that extends past the nape and may cross the shoulders. The chest is sometimes adorned with a patch of gray, brown, or blackish hairs. Infant Eastern Black Crested Gibbons are born black, unlike all other Nomascus gibbons. Females transition to yellow-beige-brown when subadult.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E30FFCAFAF8F966FECCC3B8.taxon	biology_ecology	Habitat. Previously in montane and limestone forests across northern Vietnam and south-eastern China at elevations of 50 - 930 m but now restricted to remnant tropical monsoon limestone forests at 500 - 930 m in the Cao Vit Gibbon Conservation Area, Vietnam, and the adjacent Bangliang Nature Reserve, China. The total remaining habitat in this area is only ¢. 2000 ha.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E30FFCAFAF8F966FECCC3B8.taxon	food_feeding	Food and Feeding. Preliminary and cursory studies indicated that the Eastern Black Crested Gibbon was very frugivorous, but long-term observations have shown that while levels of fruit (36 - 1 %) and fig (21: 9 %) consumption are high, substantial portions of the diet are leaves (16: 9 %) and buds (14: 4 %), with the supplementary consumption of animals (7 %), flowers (3 %), and other plant parts (0 - 7 %). Diets have included 81 plant species, which was about half the known species at one studysite, but 19 species, many of them locally rare, made up the bulk of the diet. The animal component of the diet consists largely of invertebrates, but lizards are also eaten.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E30FFCAFAF8F966FECCC3B8.taxon	breeding	Breeding. Four births of Eastern Black Crested Gibbons have been recorded in the wild in October-February; seasonality of breeding is unknown.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E30FFCAFAF8F966FECCC3B8.taxon	activity	Activity patterns. The Eastern Black Crested Gibbon is diurnal and arboreal. Activity begins just before dawn, often with loud vocalizations.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E30FFCAFAF8F966FECCC3B8.taxon	biology_ecology	Movements, Home range and Social organization. The Eastern Black Crested Gibbon forms groups that defend exclusive territories, although there is some, minimal, overlap in home ranges. Initial estimates of home ranges from three focal groups were 128 ha, 130 ha, and 133 ha, which is large for gibbons. Formation of a new territory has only been observed once and appeared to consist of the codispersal of an adult male and two juveniles into an unoccupied territory, after which they were joined by a female. It has been suggested that codispersal aids in territorial defense. The first longterm studies on the Eastern Black Crested Gibbon, along with survey data, suggest that it may be polygynous, in contrast to most other gibbons but similar to Western Black and Hainan crested gibbons. The group structure consists of an adult male and one or two adult females and offspring. A group structure with two females appears to be stable, and concurrent, dependent infants have been observed in two focal groups. The average group size of four focal groups was six individuals.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E30FFCAFAF8F966FECCC3B8.taxon	conservation	Status and Conservation. CITES Appendix I. Classified as Critically Endangered on The IUCN Red List. The Eastern Black Crested Gibbon is legally protected in China and Vietnam. It has a tiny distribution, inhabiting only ¢. 2000 ha of degraded limestone forest along the Sino-Vietnamese border. It occurs in two protected areas, which are contiguous: Cao Vit Gibbon Conservation Area in Vietnam and Bangliang Nature Reserve in China. Population estimates based on auditory surveys suggest the total transboundary population may total only 110 individuals in 18 groups, four of which occur totally or partially in China, with the remainder in Vietnam. This population was discovered in 2002 on the Vietnamese side of the border, where the majority of the population resides. Four groups were discovered on the Chinese side of the border in 2006. Cao Vit Gibbon Conservation Area in Vietnam was designated in 2007, and the contiguous Bangliang Nature Reserve in China was designated in 2009. Additional survey work in other areas of the Eastern Black Crested Gibbon’s former distribution in Vietnam has returned no more records, and it is likely that it has been extirpated in all other locations for which historical records exist. All conservation efforts are, therefore, focused on the one remaining transboundary population. Threats include ongoing degradation of the remaining habitat by local communities that use the area for collection of non-timberforest products and timber for construction and firewood. Hunting appears to be controlled, with no known cases since enforcement began in 2003. The small size of the population raises questions about its long-term genetic viability. It is vulnerable to inbreeding depression, disease outbreaks, and extreme weather events. Conservation interventions, mainly by Fauna and Flora International, on both sides of the border include working with local communities and government agencies to increase enforcement, reduce reliance of the local communities on forest resources, and build protected area management capacity. Forest regeneration and extension activities have been initiated and are likely to be important conservation actions in the future, given the highly restricted area of habitat available for the remaining Eastern Black Crested Gibbons.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E33FFCAFF2EF6BCF6BFC26B.taxon	materials_examined	China, Hainan.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E33FFCAFF2EF6BCF6BFC26B.taxon	discussion	Now commonly recognized as a distinct species from N. nasutus based on vocal and genetic evidence. Monotypic.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E33FFCAFF2EF6BCF6BFC26B.taxon	distribution	Distribution. Endemic to Hainan I, China; once widespread, but today the only known population is restricted to Bawangling Nature Reserve in the W of the island.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E33FFCAFF2EF6BCF6BFC26B.taxon	description	Descriptive notes. Head-body mean 49 - 1 cm (males, n = 2) and mean 48 - 3 cm (females, n = 3); weight 5.8 - 10 kg. As with other species of Nomascus, the Hainan Crested Gibbon is sexually dichromatic. Males are completely black, and females are brownish buff with a black crown streak and a thin white face ring. Infants are born buff and transition to black by 5 - 6 months of age, which they maintain as juveniles and subadults. Males maintain this pelage through to adulthood, but females change to their adult pelage of brownish buff at maturity.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E33FFCAFF2EF6BCF6BFC26B.taxon	biology_ecology	Habitat. Restricted to ravine microhabitats in montane forest at 700 - 1200 m above sea level. The lowland forests preferred by the Hainan Crested Gibbon are now largely destroyed on Hainan Island.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E33FFCAFF2EF6BCF6BFC26B.taxon	food_feeding	Food and Feeding. To date, the Hainan Crested Gibbon is known to select food items from 119 plant species. Food availability may be limited in February-April. At this time, they subsist on less preferred food sources. Restriction to less preferred montane forests due to the destruction of the lowland forests has implications for their feeding ecology, with lower plant diversity and fewer preferred tree species in these areas.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E33FFCAFF2EF6BCF6BFC26B.taxon	breeding	Breeding. Gestation period of the Hainan Crested Gibbon is estimated to be 136 - 173 days, and the interbirth interval is about two years, based on observations in the wild. Births are not seasonal, and infants are weaned at c. 1 - 5 years. Survivorship of infants to subadulthood can be 92 %. Between 1982 and 1989, nine of twelve infants born were male, skewing the sex ratio and potentially causing issues with mate choice within the population. Familial polygyny appears to be common. Femalesinitiate sexual encounters and are sexually receptive post-conception.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E33FFCAFF2EF6BCF6BFC26B.taxon	activity	Activity patterns. The Hainan Crested Gibbon is diurnal and arboreal. Activity begins just before dawn and often commences with loud vocalizations. Adult males lead the group during travel.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E33FFCAFF2EF6BCF6BFC26B.taxon	biology_ecology	Movements, Home range and Social organization. Group size of the Hainan Crested Gibbon is large; surveys in 2008 found that the last two groups of the species had nine and six individuals. The home ranges of these two groups are very large at 548 ha and 987 ha. It is unknown if these large home ranges are typical, are related to a lack of optimal habitat, or reflect home range expansion due to lack of competition from neighboring groups. Over 30 years of observation, these two groups of Hainan Crested Gibbons have maintained a polygynous mating strategy, with two adult females and a single adult male. Mating opportunities are restricted, however, and this may reflect abnormal behavior for the taxon — a point of contention over many years. Subadults are peripheralized until they leave the natal group. In one case, a subadult male was observed to be peripheral to his natal group for about six months before his expulsion at ¢. 5 - 5 years old. Subadults leaving the natal group may be at high risk of mortality because many have dispersed but few have been observed to form new groups.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E33FFCAFF2EF6BCF6BFC26B.taxon	conservation	Status and Conservation. CITES Appendix I. Classified as Critically Endangered on The IUCN Red List. The Hainan Crested Gibbon is legally protected in China. It occurs in just one protected area, Bawangling Nature Reserve. Three hundred years ago it inhabited most of Hainan Island — some 27,784 km? * — but several waves of habitat destruction have reduced the available habitat to only ¢. 66 km? *. Hainan Crested Gibbons are now restricted to a mere 14 - 16 km ®. The population has declined from over 2000 individuals in the 1950 s to a low point of 7 - 8 individuals in the 1970 s, with a subsequent recovery to 21 individuals in the 1980 s. Estimates since that time have varied between 13 and 20 individuals, with the current population estimated at 22; two groups of seven and eleven individuals and four solitary individuals. Although the population has increased through births in recent years, no new social groups have been formed since 2000. The small size of the population leaves it vulnerable to threats such as inbreeding depression, skewed sex ratios, disease outbreaks, and extreme weather. Other threats include habitat destruction and fragmentation, which in recent decades has been driven by agroindustry, small-scale farming, and infrastructure development. The continuing demand for Hainan Crested Gibbons for use in traditional Asian medicine also poses a threat to the remaining population, although there have been no known instances of hunting in recent years. Reducing risks from hunting and further habitat degradation through increased enforcement are priority conservation actions. Reforestation using native tree species, particularly those fed on by Hainan Crested Gibbons, will be important for the species’ survival, and some work has already begun in this area.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E33FFCBFA25F6CEFD41C146.taxon	materials_examined	Vietnam, Ja Boc, Sa Thay District, Kon Tum Province (c. 14 ° 25 ’ N, 107 ° 35 ’ E, Chu Mom Ray National Park).	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E33FFCBFA25F6CEFD41C146.taxon	discussion	This taxon was recently described based on vocal and genetic data that demonstrated it was distinct from N. sik: and N. gabriellae, the latter its closest relative. The species’ distribution covers parts of what was formerly believed to be that of N. gabriellae (to the south) and N. stki (to the north), reducing the distributions of both. Its occurrence in the central Annamite Mountains gives it its specific epithet. Monotypic.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E33FFCBFA25F6CEFD41C146.taxon	distribution	Distribution. S Laos (E of Mekong River, up to approximately the Banhiang River, 16 ° 00 ’ = 16 ° 03 ’ N, in Savannakhet Province), C Vietnam (from the Thach Han River, 16 ° 40 ’ - 16 ° 50 ” N, in Quang Tri Province in the N to approximately the Ba River, 13 ° 00 ’ = 13 ° 10 ’ N, in Gia Lai and Phu Yen provinces in the S), and NE Cambodia (Ratanakiri and Stung Treng provinces, E of the Mekong River and N of the Srepok River, 13 ° 30 ’ N).	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E33FFCBFA25F6CEFD41C146.taxon	description	Descriptive notes. Head-body 46 - 2 cm (males) and 43 - 8 cm (females); recorded weight of the adult male type specimen was 7 kg. The Northern Yellow-cheeked Crested Gibbon is largely indistinguishable from the Southern Yellow-cheeked Crested Gibbon (N. gabriellae). As with other species of Nomascus, it is sexually dichromatic, with males being predominantly black and females being buff-colored. Adult males are black, with a brown tinge on the chest, and have buff cheeks reaching less than halfway up the ears, with a rounded upper margin and brushed out away from the face. Adult females are pale to orange-yellow and have a dark crown-streak of variable size and a variable darker patch on the chest. Infants are born whitish-buff and transition to the same pelage as adult males, which they maintain as juveniles and subadults. Males maintain this pelage throughout adulthood, but females change to their adult buffy pelage at maturity.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E33FFCBFA25F6CEFD41C146.taxon	biology_ecology	Habitat. Broadleaf evergreen and semi-evergreen forest, but probably ranges into more deciduous adjacent habitat types. The Northern Yellow-cheeked Crested Gibbon has been recorded at 50 - 1205 m above sea level.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E33FFCBFA25F6CEFD41C146.taxon	food_feeding	Food and Feeding. There is limited field data on diets of Northern Yellow-cheeked Crested Gibbons. Two short studies suggest that it is frugivorous but with significant reliance on leaves, young shoots, and flowers. An instance of predation on a subadult Finlayson’s Squirrel (Callosciurus finlaysonit) by an adult female Northern Yellowcheeked Crested Gibbon and subsequent food sharing have been observed, as have instances of predation on lizards.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E33FFCBFA25F6CEFD41C146.taxon	breeding	Breeding. Two births have been recorded in a wild habituated group in Cambodia. They were in November 2008 and August 2011, suggesting an interbirth interval of about three years.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E33FFCBFA25F6CEFD41C146.taxon	activity	Activity patterns. The Northern Yellow-cheeked Crested Gibbon is diurnal and arboreal. Activity begins just prior to dawn and often commences with loud vocalizations, usually completed by 07: 00 h. One study found activity budgets of 38 % feeding, 36 % resting, 19 % traveling, and 7 % other activities. Feeding and travel frequencies are fairly uniform throughout the day, dropping off by 13: 00 h for the former and 15: 00 h for the latter as individuals settle for the night.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E33FFCBFA25F6CEFD41C146.taxon	biology_ecology	Movements, Home range and Social organization. The Northern Yellow-cheeked Crested Gibbon lives in monogamous family groups consisting of an adult pair and their immature offspring. The home range size of one group was c. 50 ha.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E33FFCBFA25F6CEFD41C146.taxon	conservation	Status and Conservation. CITES Appendix I. This newly described species has not been assessed on The IUCN Red List. The presence of the Northern Yellow-cheeked Crested Gibbon has been confirmed in 18 protected areas: Dak Rong, Phong Dien, Ba Na-Nui Chua, Song Thanh, Ngoc Linh, and Kon Cha Rang nature reserves and Bach Ma and Chu Mom Ray national parks in Vietham; Dong Phou Vieng, Xe Sap, Xe Bang Nouan, Phou Xiengthong, Dong Amphan, Dong Houa Sao, and Xe Pian biodiversity conservation areas in Laos; and Virachey National Park in Cambodia. In Vietnam, ¢. 200 groups have been recorded between 2000 and 2011, although this represents a minimum number. Key populations are thought to occur in the contiguous Dak Rong and Phong Dien nature reserves, and additional important populations may occur in Kon Cha Rang Nature Reserve and Song Thanh, Ngoc Linh, and Kon Cha Rang nature reserves and surrounding forests. Although data are lacking, populations in Laos are likely significant, but it is inferred that they are declining, with none in effectively managed protected areas. Some locations in Laos, such as Xe Sap National Protected Area, afford good natural protection. Populations in Cambodia are likely to be very important, the most significant being in Virachey National Park with an estimate of over 10,000 individuals, although based on very limited survey data. The adjacent Veun Sai-Siem Pang Conservation Area has a population estimate of ¢. 500 groups and is currently under management. The Northern Yellow-cheeked Crested Gibbon is threatened by habitat loss, hunting, and collection for the pet trade. In Cambodia, large areas of habitat in Virachey National Park are being cleared for rubber plantations, and a mining concession over most of the protected area poses threats to this core population. Compared with the more northerly distributed species of Nomascus, however, populations of the Northern Yellow-cheeked Crested Gibbon are relatively robust and intact.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E32FFCCFF07F529FBA3CAC3.taxon	materials_examined	Siam. Restricted by J. Fooden in 1987 to Laos, Muang Khi.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E32FFCCFF07F529FBA3CAC3.taxon	discussion	Two subspecies, leucogenys and siki, have been recognized in the past, but most authorities now treat these as separate species based on genetic and morphological evidence. In the past, there would have been contact zones with N. concolor in Yunnan, China, and they may still occur in north-western Laos, but whether there is sympatry or hybridization is not known. Monotypic.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E32FFCCFF07F529FBA3CAC3.taxon	distribution	Distribution. S China (extreme S Yunnan Province), N Laos, and NW Vietnam between the Mekong and Black rivers, to the S possibly limited by the Khading River in Laos and the Rao Nay River in Ha Tinh Province in Vietnam.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E32FFCCFF07F529FBA3CAC3.taxon	description	Descriptive notes. Head-body 47 - 525 cm (n = 5 males and 2 females); weight of males 6 - 4 kg (SD 0 - 9 kg, n = 5) and of females 6 - 6 kg (SD 0 - 6 kg, n = 5). Adult males and juveniles of both sexes of the Northern White-cheeked Crested Gibbon are black with white cheek-whiskers that form a narrow streak starting under the chin and reaching to the tops of the ears. Adult females are pale yellow to orange-yellow, with a black to brown crown streak and thin white face-ring that may or may not be complete. Hair in both sexesis long (40 - 70 mm) and rather coarse. The crown hair is erect and elongated in the middle, forming a high crown crest in the male but absentin the female.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E32FFCCFF07F529FBA3CAC3.taxon	biology_ecology	Habitat. Tall primary and mature secondary tropical broadleaf evergreen and semievergreen forest and also high-elevation, mixed coniferous forests in Vietnam. Elevational distribution of the Northern White-cheeked Crested Gibbon is 200 - 1650 m above sea level, and although it may prefer lowland habitats, it is now largely found above 700 m due to loss of habitat.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E32FFCCFF07F529FBA3CAC3.taxon	food_feeding	Food and Feeding. There is some preliminary evidence that the Northern Whitecheeked Crested Gibbon is less frugivorous than is typical of most gibbons. Leaves (36 %) and shoots (17 %) comprise the largest proportion of the diet, with significant amounts of fruit (39 %) and small amounts of flowers (4 - 4 %) and insects (3 - 6 %). Fruit is consumed at higher frequencies during periods of high availability in the rainy season; they eat more leaves and travel greater distances in the dry season.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E32FFCCFF07F529FBA3CAC3.taxon	breeding	Breeding. Limited data are available on reproductive parameters in both wild and captive white-cheeked gibbons. The gestation period is 200 - 212 days. There is no conclusive evidence for birth seasonality. Infants have a whitish-buff natal coat that changes to the dark color phase at 6 - 18 months, which males retain into adulthood. With sexual maturity, females change again, from their blackjuvenile coat to the characteristic yellow or buffy coat of adults, with a complete color-phase change occurring between six years and eight years and eight months in one female. Sexual maturity occurs at 6 - 8 years of age, but captive white-cheeked gibbons have bred as early as four years old. Average life span in the wild is unknown, but captive individuals have lived for up to 45 years.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E32FFCCFF07F529FBA3CAC3.taxon	activity	Activity patterns. The Northern White-cheeked Crested Gibbon is diurnal and arboreal. Activity begins just before dawn, often with loud calls.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E32FFCCFF07F529FBA3CAC3.taxon	biology_ecology	Movements, Home range and Social organization. Very little is known about the behavioral ecology of white-cheeked gibbons. Most information comes from the very small Chinese population and details about the Laotian and Vietnamese populations are based on anecdotal field observations. Nevertheless, life history characteristics of this species seem to be similar to those of other gibbons. It is territorial, living in monogamous family groups of an adult pair and their immature offspring. Average group size in Yunnan Province, China, was 3 - 8 individuals (range 3 - 5, n = 9), and anecdotal reports from Vietnam suggest group sizes of 3 - 5 individuals.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E32FFCCFF07F529FBA3CAC3.taxon	conservation	Status and Conservation. CITES Appendix I. Classified as Critically Endangered on The IUCN Red List. The Northern White-cheeked Gibbon is legally protected in China, Vietnam, and Laos. It occurs in 16 protected areas: Shangyong and Mengla nature reserves in Yunnan, China; Muong Nhe, Pu Hu, Xuan Lien, Pu Hoat, Pu Huong, and Ke Go nature reserves and Pu Mat and Vu Quang national parks in Vietnam; and Nam Et, Phou Louey, Nam Xam, Nam Kading, Phou Dene Din, Phou Phanang and Phou Khao Khoay biodiversity conservation areas in Laos. Population estimates, even from individual sites, are largely lacking. In Laos, there have been no population surveys, but due to the country’s large areas of remaining habitat inside protected areas, it is assumed to hold the majority of Northern White-cheeked Gibbons. Key population centers are likely Nam Et, Phou Louey, Nam Xam, and Nam Kading protected areas north of the Kading River. The population in Vietnam is better documented, with an estimate of less than 300 groups. Pu Mat National Park likely holds the largest Vietnamese population, with an estimated 130 groups. Other key sites may include Muong Nhe Nature Reserve and Vu Quang National Park, with few othersites in Vietnam holding viable populations and extinctions in a number of protected areas. It is likely that local extinctions will continue to occur in the near future. In China, the population of Northern White-cheeked Gibbons has declined drastically over past decades, due largely to hunting and habitat loss, and it is now restricted to two reserves, Mengla and Shangyong in Xishuangbanna Prefecture, with some reports also coming from Ly Chun County. The population may now be as small as ten individuals in three groups, with little prospect for long-term survival. Hunting for food, traditional Asian medicine, and the pet trade, combined with habitat loss, degradation and fragmentation across its range have resulted in the current dire conservation status of this gibbon. Where it occurs, populations are often small and highly fragmented, rather than evenly distributed in suitable habitats. Areas of intact forest often lack significant numbers because of hunting. Large-scale habitat conversion, along with firewood collection, human settlement, agricultural production, and timber extraction, driven by increasing human populations, remain significant threats. Conservation actions for the Northern White-cheeked Gibbon are largely lacking. In general, protected areas where it occurs are not effectively management, and only two population strongholds in the Nam Et, Phou Louey, and Nam Kading areas of Laos receive sufficient attention. Populations in Vietnam remain effectively unprotected and will continue to decline at significant rates, with local extirpations expected without conservation interventions. The long-term outlook for the few remaining individuals in China remains bleak. Effective site-based conservation that controls hunting and habitat loss and fragmentation is necessary for the survival of the Northern White-cheeked Gibbon in China. Population monitoring should be initiated in major population strongholds where site-based conservation is being effectively implemented. It is most important that the wildlife trade be controlled if it is to survive.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E35FFCCFF20FDA5F59ACAC4.taxon	materials_examined	Vietnam, Thua Luu.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E35FFCCFF20FDA5F59ACAC4.taxon	discussion	Occasionally treated as a subspecies of N. leucogenys, but most authorities now recognize it as a distinct species based on genetic and morphological data. While the type locality is in the range of the newly described N. annamensis, the putative locality is disputed and the holotype morphologically represents N. siki. The recent description of N. annamensis and the southerly extension of the distribution of N. leucogenys have considerably reduced what was believed to be the distribution ofthis species. Monotypic.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E35FFCCFF20FDA5F59ACAC4.taxon	distribution	Distribution. C Laos and C Vietnam, restricted by the Rao Nay River in Vietnam and the Khading River in Laos in the N, the Mekong River in the W, the Vietnamese coastal agricultural areas in the E, and around the Thach Han River (16 ° 40 ’ - 16 ° 50 " N) in Quang Tri Province, Vietnam, and the Savannakhet Province in Laos, to the S.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E35FFCCFF20FDA5F59ACAC4.taxon	description	Descriptive notes. No specific body measurements are available; weight of males 6 - 6 kg (SD 0 - 5 kg, n = 4) and of females 7 - 9 kg (SD 1 - 7 kg, n = 3). Adult males and juveniles of both sexes of the Southern White-cheeked Crested Gibbon are black with white cheek whiskers, which are similar to those of the Northern White-cheeked Crested Gibbon (N. leucogenys) but they reach only halfway up to the ears. Cheek whiskers have a pointed upper end and bracket the mouth, extending along the margin of the upper lips and onto sides of the chin and are not brushed outward as in the Northern Yellowcheeked Crested Gibbon (N. annamensis) and the Southern Yellow-cheeked Crested Gibbon (N. gabriellae). The crest is well developed, but less so than in the Northern White-cheeked Crested Gibbon. Females are pale yellow to orange-yellow, with a dark crown streak and white circumfacial hair, and are largely indistinguishable from female Northern White-cheeked Crested Gibbons.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E35FFCCFF20FDA5F59ACAC4.taxon	biology_ecology	Habitat. Tall primary tropical broadleaf evergreen forest and steep karst forest. The Southern White-cheeked Crested Gibbon occurs at 30 - 1800 m above sea level, but it may occur at higher altitudes.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E35FFCCFF20FDA5F59ACAC4.taxon	food_feeding	Food and Feeding. There is no specific information available for this species, but it is presumably similar to other species of Nomascus (i. e. largely frugivorous with the diet supplemented mostly by leaves and flowers).	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E35FFCCFF20FDA5F59ACAC4.taxon	breeding	Breeding. There is no information available for this species.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E35FFCCFF20FDA5F59ACAC4.taxon	activity	Activity patterns. The Southern White-cheeked Crested Gibbon is diurnal and arboreal. Activity begins just prior to dawn, often with loud vocalizations.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E35FFCCFF20FDA5F59ACAC4.taxon	biology_ecology	Movements, Home range and Social organization. Very little is known about the Southern White-cheeked Crested Gibbon in the wild; no behavioral or ecological studies have been carried out. It is likely to be similar to the closely related Northern Whitecheeked Crested Gibbon and the two species of yellow-cheeked gibbons in being territorial and monogamous and living in family groups of one male, one female, and up to three offspring.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E35FFCCFF20FDA5F59ACAC4.taxon	conservation	Status and Conservation. Listed on CITES Appendix I. Classified as Endangered on The IUCN Red List. The Southern White-cheeked Crested Gibbon may require reassessment based on a large reduction of its distribution caused by the description of the Northern Yellow-cheeked Crested Gibbon, which occupies much of what was formerly believed to be the southern part of its range. It occurs in much of what was formerly believed to be the southern distribution of the Southern White-cheeked Crested Gibbon. The Southern White-cheeked Crested Gibbon is known to occurin six protected areas: Phong Nha-Ke Bang National Park and Bac Huong Hoa Nature Reserve in Vietnam and Nam Kading, Phou Hin Boun, Hin Nam No and probably Nakai-Nam Theun national protected areas in Laos. Its status is not well documented at any site where it occurs. Key sites in Laos are likely to be the biodiversity conservation areas of Nam Kading, south of the Kading River, and Nakai-Nam Theun. Other areas such as Phou Hin Boun and Him Nam No biodiversity conservation areas likely have significant populations, being naturally well protected. The long-term financing of Nakai-Nam Theun from hydropower interests and poor access to Phou Hin Boun suggest these sites will be key for the long-term conservation of the Southern White-cheeked Crested Gibbon. The two protected areas where it occurs in Vietnam (Phong Nha-Ke Bang and Bac Huong Hoa), along with their adjacent forests, adjoin protected areas in Laos. The principal threat to the Southern White-cheeked Crested Gibbon is hunting. Hunting is largely opportunistic, with individuals being used locally for meat and traded for use in medicinal products and as pets (infants). This is exacerbated by habitat degradation and loss and, in some instances, infrastructure development, although disentangling these issues from hunting is problematic. Habitat fragmentation is more a serious threat in Vietnam than in Laos; human population pressure is greater in Vietnam, with correspondingly more widespread agriculture and logging. Reducing hunting and habitat loss are key for the Southern White-cheeked Crested Gibbon, especially controlling these threats in priority protected areas.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E35FFCDFA27FDACFD94C955.taxon	materials_examined	Vietnam, Langbian, 460 m.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E35FFCDFA27FDACFD94C955.taxon	discussion	The taxon’s distribution was previously thought to include more northerly areas, including southern Laos and southcentral Vietnam, but this was reduced with the taxonomic split and subsequent description of N. annamensis. Monotypic.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E35FFCDFA27FDACFD94C955.taxon	distribution	Distribution. S Vietnam (from Ba River, 13 ° 00 ’ - 13 ° 10 ’ N, in Gia Lai and Phu Yen provinces in the N to the Nui Ong Nature Reserve, 11 ° 01 ’ N, in Binh Thuan Province in the S) and SE Cambodia (E of the Mekong River and S of the Srepok River).	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E35FFCDFA27FDACFD94C955.taxon	description	Descriptive notes. Head-body 45.5 - 49.5 cm (males, n = 4) and 4647 - 5 cm (females, n = 2); weight of females 5 - 2 kg (SD 5 - 9 kg, n = 3). As with other species of Nomascus, the Southern Yellow-cheeked Crested Gibbon is sexually dichromatic. Males are predominantly black, and females are buffy-colored. Adult males are black with slightly rusty-colored chests, yellowish to orangey cheeks, and a partial beard, which is brushed outward. This is in contrast to the white cheeks of the Southern White-cheeked Crested Gibbon (N. siki) and the Northern White-cheeked Crested Gibbon (N. leucogenys). Adult females are pale yellow to orangey-yellow, have a variable black crown streak, and may show a slightly darker chest. Infants are born buffy-yellow and begin to transition to the same pelage as adult males at about six months old, maintaining this coloration as juveniles and subadults. Males maintain this pelage through to adulthood, but females change to their adult pelage color as they reach maturity.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E35FFCDFA27FDACFD94C955.taxon	biology_ecology	Habitat. Wet evergreen and semi-evergreen forests of the Indochina lowlands and also in mixed deciduous and bamboo forests, but possibly limited to where these forest types are found in association with preferred habitats. The Southern Yellow-cheeked Crested Gibbon does not occur in dry deciduous dipterocarp forests that are common in its range. It occurs in higher densities in undisturbed habitats. It has been recorded at 100 - 2287 m above sea level, and reports indicate that it might occur at higher elevations but at lower densities.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E35FFCDFA27FDACFD94C955.taxon	food_feeding	Food and Feeding. Diets of Southern Yellow-cheeked Crested Gibbons are dominated by figs (38: 6 %) and otherfruits (43 %), and supplemented with new and mature leaves (9: 5 %) and flowers (8: 9 %). This high degree of frugivory contrasts with the northerly distributed species of Nomascus that include more leaves in their diets.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E35FFCDFA27FDACFD94C955.taxon	breeding	Breeding. A single interbirth interval of 17 - 22 months was recorded in the wild.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E35FFCDFA27FDACFD94C955.taxon	activity	Activity patterns. The Southern Yellow-cheeked Crested Gibbon is diurnal and arboreal. Activity beginsjust before dawn and often commences with loud calls, the majority of them in the 30 minutes around sunrise. Singing bouts average about twelve minutes.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E35FFCDFA27FDACFD94C955.taxon	biology_ecology	Movements, Home range and Social organization. Groups of Southern Yellow-cheeked Crested Gibbons are socially monogamous, comprising an adult pair and offspring; groups average 4 - 5 individuals (range 3 - 6). Extrapair copulations have been recorded but are infrequent. Females tend to disperse to new territories near their natal territories after reaching maturity, while males emigrate more widely. Home ranges are 14 - 2 - 60 - 5 ha, averaging 41 ha. Defended territories are smaller, averaging 37 ha.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E35FFCDFA27FDACFD94C955.taxon	conservation	Status and Conservation. CITES Appendix I. Classified as Endangered on The IUCN Red List. The Southern Yellow-cheeked Crested Gibbon is legally protected in Vietnam and Cambodia. It occurs in 15 protected areas: Yok Don, Chu Yang Sin, Bi Dup-Nui Ba, Phuoc Binh, Bu Gia Map, and Cat Tien national parks and Hon Ba, Nam Nung, Ta Dung, Dong Nai, and Nui Ong nature reserves in Vietnam and Phnom Prich, Snoul, and Phnom Nam Lyr wildlife sanctuaries and Seima Protection Forest in Cambodia. The most significant Cambodian population is found in Seima Protection Forest, estimated at 432 - 972 groups based on surveys using a number of different techniques. While spot surveys have been conducted in several other protected areas, the only other population survey using an appropriate method and sample size is from Phnom Prich Wildlife Sanctuary, which resulted in an estimate of 15 - 273 groups. In Vietnam, areas with large and important populations are Cat Tien National Park with a minimum estimate of 149 groups and Bu Gia Map National Park with an estimated 124 groups. These two protected areas and surrounding forests are the priority sites for the species’ conservation in Vietnam, but other significant populations likely exist. Cat Tien National Park also houses the Dao Tien Endangered Primate Species Centre that holds confiscated gibbons and conducts reintroductions into the park. Hunting for the wildlife trade is a major threat, with individuals taken from the wild for zoos and private collections in southern Vietnam. There is a market for infants that are acquired by shooting the mother, which adversely affects population recovery. Habitat loss is also significant, with planned and unplanned forest conversion and severe degradation in and around some protected areas caused by infrastructure development, agricultural encroachment, and illegal logging. Populations in Seima Protection Forest and Phnom Prich Wildlife Sanctuary in Cambodia are under active and effective management, while populations in Cat Tien and Bu Gia Map national parks in Vietnam have been the focus of gibbon-specific conservation activities over recent years.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E34FFCDFFEFFC96F820C78B.taxon	materials_examined	Indonesia, West Sumatra, Bencoolen (= Bintuhan).	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E34FFCDFFEFFC96F820C78B.taxon	discussion	Some authorities recognize the mainland and Sumatran populations as two distinct subspecies, continentis and syndactylus, respectively. Siamangs are sympatric with Hylobates lar on the Malay Peninsula and northern Sumatra and with H. agilis in southern Sumatra. Monotypic.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E34FFCDFFEFFC96F820C78B.taxon	distribution	Distribution. Malay Peninsula in S Thailand (only in a small area on the border with Malaysia), NW & C Peninsular Malaysia (largely restricted to mountainous areas in the W of the country, S of the Perak River and N of the Muar River, and Tasek Bera across to the Pahang River), and W Sumatra where confined to the Barisan Mts; it may have formerly occurred on Bangka I.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E34FFCDFFEFFC96F820C78B.taxon	description	Descriptive notes. Head — body 75 - 90 cm; weight 10.5 - 12.7 kg (males) and 9.1 - 11.5 kg (females). The Siamang has an intermembral index of 138 - 141. All age and sex classes have black pelage, although mature individuals may develop creamy hairs on the chin, and a white brow band occurs in a minority of individuals, mainly females. Siamangs have a large inflatable throat sac, the second and third toes are variably webbed (syndactylous), and males have a prominent genital tuft.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E34FFCDFFEFFC96F820C78B.taxon	biology_ecology	Habitat. Lowland, submontane, and montane forests, including dipterocarp forests. Siamangs can inhabit primary and secondary forests, including selectively logged forest, albeit at lower densities. Siamangs are found at higher elevations than sympatric gibbons, potentially facilitated by their larger size that aids in thermoregulation and a more flexible diet that can include higher proportions of leaves. Siamangs are commonly found up to 1500 - 2000 m above sea level and have been recorded up to 2300 m in Kerinci-Seblat National Park.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E34FFCDFFEFFC96F820C78B.taxon	food_feeding	Food and Feeding. Siamangs are largely frugivorous, although less so than sympatric species of Hylobates. A large proportion of the diet is composed of figs (Ficus, Moraceae). Populations in Sumatra have higher levels of frugivory than those in Malaysia, potentially because of higher fruit availability and the inclusion of figs in the diet. Relative frequencies of feeding on different food types, with figures being averages taken from all studies on the species, are 42 -: 2 % leaves, 32 % figs, 12 % fruit, 9 - 4 % insects, and 4 - 4 % flowers. Figs are particularly preferred in the early morning and late afternoon, which may represent a strategy to offset energy debt incurred during the night. While feeding, climbing is the most commonly used locomotion between food patches, and supports used during feeding are generally smaller than those used for travel. The relatively large forelimb to hindlimb weights, compared with other hylobatids, also suggest that the Siamang is specialized for forelimb climbing. Siamangs most commonly hang when eating fruit, suggesting that, despite being larger than other hylobatids, they are still adapted for terminal-branch feeding. They are sympatric with the smaller gibbon taxa, the Agile Gibbon (H. agilis) and the Lar Gibbon (H. lar), over much of their distribution and have a great deal of dietary overlap with them. All three species rely heavily on figs, but the Siamang supplements its diet with young leaves, while the two gibbon taxa supplement their diets more with pulpy fruits, avoiding competition to some extent. Siamangs often displace groups of Agile and Lar gibbons from preferred food sources.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E34FFCDFFEFFC96F820C78B.taxon	breeding	Breeding. In captivity, adult male Siamangs breed as early as 4 - 3 years of age and females at 5 - 2 years, although reproductive maturity occurs more commonly at 8 - 9 years, as suggested by data on wild individuals. Copulation is usually dorso-ventral, but instances of ventro-ventral copulation have been recorded. The gestation period is 189 - 239 days. Births may be seasonal coinciding with high fruit abundance, but evidence is lacking to confirm this. A single observed wild birth suggests that females reduce their activities significantly in the days before giving birth. Generally, a single young is born; twins are rare. Neonatal weight averages 540 g (n = 46), with no difference between male and female neonates. Infants start taking solid food by 3 - 9 months of age, are largely weaned by twelve months, and completely independent when two years old. Interbirth intervals may exceed three years, based on limited longitudinal information from a few individuals, and, consequently, lifetime reproductive output is likely to be 5 - 10 offspring / female.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E34FFCDFFEFFC96F820C78B.taxon	activity	Activity patterns. Siamangs become active around sunrise and retire to sleeping trees ¢. 16: 00 h, with an average daily activity period of about ten hours. Sleeping trees may be centrally located in their territories. Calling usually occurs after dawn and generally after the first feeding bout of the day. One group’s calls inhibit the calling of other nearby groups, with groups taking turns. Calling may only occur on 30 % of days, although this is highly variable and is possibly linked to times of peak availability of fruit and periods of reproductive activity. Unmated adult males sing solos. Based on several studies on both Peninsular Malaysia and Sumatra, activity budgets can be summarized as dominated by feeding (35 - 50 %) and resting (25 - 44 %), with less time spent traveling (12 - 22 %). Social activities, such as singing and calling, playing, and grooming are infrequent. Feeding and travel peak in the morning, with a steady increase in resting as the day continues. The majority of activity occurs in the middle and upper canopy. They use the lower canopy infrequently, feeding there sometimes in the heat of the day. Siamangs have a diverse locomotory repertoire while traveling, including brachiation (51 %), climbing (37 %), bipedalism (6 %), and leaping (6 %). Travel consists mainly of movement between food sources and sleeping trees, generally following frequently used arboreal highways. A Diard’s Clouded Leopard (Neofelis diardi) has been recorded taking a juvenile Siamang. Anti-predator behaviors may include sleeping in tall trees and forming mixed-species groups with langurs.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E34FFCDFFEFFC96F820C78B.taxon	biology_ecology	Movements, Home range and Social organization. Home ranges of Siamangs are 15 — 24 ha, often with some overlap between groups and sympatric Agile and Lar gibbons. Intergroup encounters at common territorial borders occur regularly. They involve calling by males and females, and males chasing males along the boundary. Daily travel distances are variable between groups, locations, and potentially season. They are 400 — 3000 m / day, generally averaging 1000 - 1200 m. Females usually lead the group when traveling, with independent young following next, then the adult male, and behind them, adolescents. Groups are normally highly cohesive and contain 3 - 4 - 3 - 9 individuals. While usually monogamous, polyandry may occur, with a single female and two, usually unrelated, males. The role of polyandry does not appear to be related to the female’s need for additional help in raising infants because groups with two males collectively provide less parental care than those with a single male. Siamangs are unique among the Hylobatidae because males usually become the primary caregiver for infants during their second year of life. By carrying infants, males reduce female energy output during this phase of reproductive effort, leading to shorter interbirth intervals. At one site, turnover of mates appears to be common, with many instances of pairbond dissolution through individuals of either sex leaving their mate and transferring to other groups. As they mature, adolescents are peripheralized by the adult male and female, and by four years old, they may move behind the group and sleep in trees apart from the rest of the group until eventually they move on to establish a new territory. Dispersing males are evidently quite philopatric, whereas females appear to disperse more widely. Intragroup aggression is most commonly targeted at adolescents. Grooming usually involves the adult male as a member of grooming dyads, most commonly with adult females and subadult males. Duetting in Siamang likely improves pair bonding, although itis also probably a territorial advertisement. Population density is highly variable across studies, probably linked to habitat type, with 2: 4 - 24 - 6 ind / km?. Preference, as seen under higher densities, may be for lowland and montane forests, with hill dipterocarp and submontane forest less preferred. Inverse relationships in densities among Siamangs and sympatric Agile and Lar gibbons in different habitat types have been noted in several studies, suggesting niche differentiation. Densities of Siamangs may decrease in a south-north cline in Sumatra.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
03D787BA0E34FFCDFFEFFC96F820C78B.taxon	conservation	Status and Conservation. CITES Appendix I. Classified as Endangered on The IUCN Red List. The Siamang is legally protected in Thailand, Malaysia, and Indonesia. It is known to occur in at least ten protected areas: Hala Bala Wildlife Sanctuary in Thailand; Krau Wildlife Reserve, Fraser's Hill Forest Reserve, Gunung Besout Forest Reserve, and Ulu Gombak Wildlife Reserve in Malaysia; and Gunung Leuser, Kerinci-Seblat, Bukit Barisan Selatan, and Way Kambas national parks and West Langkat Reserve in Sumatra, Indonesia. It is threatened by habitat destruction and degradation caused by conversion for agriculture and other uses, logging, both legal and illegal, drought, and fire. Siamangs are hunted for pets and use in traditional Asian medicine. Populations are in decline and may be seriously affected by the large-scale loss of lowland forest habitats. One estimate placed the loss of Siamang habitat on Sumatra at 40 % between 1995 and 2000. EI Nino / Southern Oscillation events leading to widespread fires (exacerbated by logging, which dries out the forest floor) have been implicated in increased infant and Juvenile mortality. Increasing frequencies of these events could result in mortality rates becoming higher than replacement rates. The Siamang is the most common gibbon in the pet trade in Indonesia; it is also commonly found in markets in Sumatra, Java, and Bali. Population estimates of wild Siamangs are lacking from all but Bukit Barasan Selatan National Park, which has 4876 - 6606 groups or ¢. 22,390 individuals.	en	Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson (2013): Hylobatidae. In: Handbook of the Mammals of the World – Volume 3 Primates. Barcelona: Lynx Edicions: 778-791, ISBN: 978-84-96553-89-7, DOI: 10.5281/zenodo.6727957
