The hoolock gibbons are three
primate
Primates are a diverse order of mammals. They are divided into the strepsirrhines, which include the lemurs, galagos, and lorisids, and the haplorhines, which include the tarsiers and the simians (monkeys and apes, the latter including huma ...
species of genus ''Hoolock'' in the gibbon family,
Hylobatidae
Gibbons () are apes in the family Hylobatidae (). The family historically contained one genus, but now is split into four extant genera and 20 species. Gibbons live in subtropical and tropical rainforest from eastern Bangladesh to Northeast India ...
, native to eastern
Bangladesh
Bangladesh (}, ), officially the People's Republic of Bangladesh, is a country in South Asia. It is the eighth-most populous country in the world, with a population exceeding 165 million people in an area of . Bangladesh is among the mos ...
,
Northeast India
, native_name_lang = mni
, settlement_type =
, image_skyline =
, image_alt =
, image_caption =
, motto =
, image_map = Northeast india.png
, ...
,
Myanmar
Myanmar, ; UK pronunciations: US pronunciations incl. . Note: Wikipedia's IPA conventions require indicating /r/ even in British English although only some British English speakers pronounce r at the end of syllables. As John C. Wells, Joh ...
, and
Southwest China
Southwest China () is a region in the south of the People's Republic of China.
Geography
Southwest China is a rugged and mountainous region, transitioning between the Tibetan Plateau to the west and the Chinese coastal hills (东南丘陵) and ...
.
Description
Hoolocks are the second-largest of the gibbons, after the
siamang
The siamang (, ; ''Symphalangus syndactylus'') is an arboreal, black-furred gibbon native to the forests of Indonesia, Malaysia, and Thailand. The largest of the gibbons, the siamang can be twice the size of other gibbons, reaching in height, a ...
. They reach a size of 60 to 90 cm and weigh 6 to 9 kg. The sexes are about the same size, but they differ considerably in coloration; males are black-colored with remarkable white brows, while females have a grey-brown fur, which is darker at the chest and neck. White rings around their eyes and mouths give their faces a mask-like appearance. The ''
Oxford English Dictionary
The ''Oxford English Dictionary'' (''OED'') is the first and foundational historical dictionary of the English language, published by Oxford University Press (OUP). It traces the historical development of the English language, providing a com ...
'' says that the name "hoolock" is from "a language of Assam."
Distribution
In northeast India, the hoolock is found south of Brahmaputra and the North Bank areas and east of the Dibang Rivers. Its range extends into seven states covering
Arunachal Pradesh
Arunachal Pradesh (, ) is a state in Northeastern India. It was formed from the erstwhile North-East Frontier Agency (NEFA) region, and became a state on 20 February 1987. It borders the states of Assam and Nagaland to the south. It shares int ...
,
Assam
Assam (; ) is a state in northeastern India, south of the eastern Himalayas along the Brahmaputra and Barak River valleys. Assam covers an area of . The state is bordered by Bhutan and Arunachal Pradesh to the north; Nagaland and Manipur ...
,
Manipur
Manipur () ( mni, Kangleipak) is a state in Northeast India, with the city of Imphal as its capital. It is bounded by the Indian states of Nagaland to the north, Mizoram to the south and Assam to the west. It also borders two regions of Myanm ...
,
Meghalaya
Meghalaya (, or , meaning "abode of clouds"; from Sanskrit , "cloud" + , "abode") is a states and union territories of India, state in northeastern India. Meghalaya was formed on 21 January 1972 by carving out two districts from the state of As ...
,
Mizoram
Mizoram () is a state in Northeast India, with Aizawl as its seat of government and capital city. The name of the state is derived from "Mizo people, Mizo", the endonym, self-described name of the native inhabitants, and "Ram", which in the Mizo ...
,
Nagaland
Nagaland () is a landlocked state in the northeastern region of India. It is bordered by the Indian states of Arunachal Pradesh to the north, Assam to the west, Manipur to the south and the Sagaing Region of Myanmar to the east. Its capital cit ...
, and
Tripura
Tripura (, Bengali: ) is a state in Northeast India. The third-smallest state in the country, it covers ; and the seventh-least populous state with a population of 36.71 lakh ( 3.67 million). It is bordered by Assam and Mizoram to the east a ...
(The seven northeastern states of India).
In Bangladesh, the western hoolock gibbons were distributed across 35 forest fragments. The largest of these (Lawachara and Kaptai) supported 42 and 84 individuals respectively, but 17 of the fragments had less than ten individuals. For a better overview the forest fragments are grouped into 13 areas. All areas are located within Chittagong and Sylhet divisions, mostly near the eastern border of the country. In China, in historical times, the skywalker gibbon was recorded in nine counties in the west bank of the Salween River in westernmost Yunnan province. Based on more recent interview surveys conducted in Oct-Nov 2008 and field surveys conducted in Mar, Apr, and Aug 2009, the current Chinese population of hoolock gibbons was found to be restricted to three counties (Baoshan, Tengchong, and Yingjiang). The population size was estimated to be less than 200 individuals. In Myanmar, all three species of hoolock gibbon can be found in the forested areas west of Thanlwin river. Of all four distribution countries, Myanmar holds the key population of all three species.
[Geissmann, T., Grindley, M. E., Ngwe Lwin, Saw Soe Aung, Thet Naing Aung, Saw Blaw Htoo, and Momberg, F. (2013). The conservation status of hoolock gibbons in Myanmar. Gibbon Conservation Alliance, Zürich, Switzerland, xii + 157 pp]
Behaviour and diet
Like the other gibbons, they are
diurnal and
arboreal
Arboreal locomotion is the Animal locomotion, locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally, but others are exclusively arboreal. Th ...
,
brachiating through the trees with their long arms. They live together in monogamous pairs, which stake out a territory. Their calls serve to locate family members and ward off other gibbons from their territory. Their diet consists mainly of fruits, insects and leaves.
Breeding and lifecycle
Young hoolocks are born after a 7-month gestation, with milky white or buff-colored hair. After about 6 months, the hair of males darkens and turns black, while the females' hair remains buff-colored throughout their lives. After 8-9 years, they are fully mature and their fur reaches its final coloration. Their life expectancy in the wild is about 25 years.
Classification
![Mâle Gibbon Hoolock de l'Ouest](https://upload.wikimedia.org/wikipedia/commons/e/e9/M%C3%A2le_Gibbon_Hoolock_de_l%27Ouest.jpg)
The classification of this gibbon has changed several times in the past few years. Classically, all gibbons were classified in the genus ''Hylobates'', with the exception of the siamang. After some studies, the genus was divided into three subgenera (including the siamang's ''Symphalangus''), and then into four (recognizing ''
Bunopithecus
''Bunopithecus'' is an extinct genus of primate represented by one species, ''Bunopithecus sericus'', a gibbon or gibbon-like ape. Its remains were first discovered in Sichuan, China, in strata from the Middle Pleistocene.
Although the three hoo ...
'' as the hoolock subgenus distinct from other gibbon subgenera). These four subgenera were elevated to full genus status. However, the
type species
In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...
for ''Bunopithecus'' is ''
Bunopithecus sericus
''Bunopithecus'' is an extinct genus of primate represented by one species, ''Bunopithecus sericus'', a gibbon or gibbon-like ape. Its remains were first discovered in Sichuan, China, in strata from the Middle Pleistocene.
Although the three hoo ...
'', an extinct gibbon or gibbon-like ape from
Sichuan
Sichuan (; zh, c=, labels=no, ; zh, p=Sìchuān; alternatively romanized as Szechuan or Szechwan; formerly also referred to as "West China" or "Western China" by Protestant missions) is a province in Southwest China occupying most of the ...
, China. Very recent investigations have shown that the hoolock gibbons are not closely related to ''B. sericus'', so they have been placed in their own genus, ''Hoolock''. In the process, the two subspecies of hoolock gibbons have been raised to species level.
[ A new subspecies of the western hoolock gibbon has been described recently from northeastern India, which has been named the Mishmi Hills hoolock gibbon, ''H. hoolock mishmiensis''.] A further new species, ''H. tianxing'', with an estimated population of about 200, was discovered in southwest China in 2017.
The species of hoolock are:
* Western hoolock gibbon
The western hoolock gibbon (''Hoolock hoolock'') is a primate from the gibbon family, Hylobatidae. The species is found in Assam, Mizoram, and Meghalaya in India, Bangladesh, and Myanmar west of the Chindwin River.
Classification
Mootnick an ...
, ''H. hoolock''
* Eastern hoolock gibbon
The eastern hoolock gibbon (''Hoolock leuconedys'') is a primate from the gibbon family, Hylobatidae. It is one of three species of hoolock gibbon. This species is found in east of the Chindwin River, such as the Mahamyaing Wildlife Sanctuary, a ...
, ''H. leuconedys''
* Skywalker hoolock gibbon
The Skywalker hoolock gibbon or Gaoligong hoolock gibbon (''Hoolock tianxing'') is an arboreal primate in the gibbon family, Hylobatidae. It is one of three species of hoolock gibbon and was first described in January 2017 in the ''American Jour ...
, ''H. tianxing''
References
External links
*ARKive
images and movies of the hoolock gibbon ''(Bunopithecus hoolock)''
Gibbon Conservation Center
Hoolock gibbon photos taken in the wild
Primate Info Net ''Hoolock'' factsheet
{{Taxonbar, from=Q303166
Gibbons