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Gee's golden langur (''Trachypithecus geei''), also known as simply the golden langur, is an
Old World monkey Old World monkeys are primates in the family Cercopithecidae (). Twenty-four genera and 138 species are recognized, making it the largest primate family. Old World monkey genera include baboons (genus '' Papio''), red colobus (genus '' Piliocolob ...
found in a small region of Western Assam,
India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...
and the neighboring foothills of the Black Mountains of
Bhutan Bhutan, officially the Kingdom of Bhutan, is a landlocked country in South Asia, in the Eastern Himalayas between China to the north and northwest and India to the south and southeast. With a population of over 727,145 and a territory of , ...
. Long considered sacred by many
Himalaya The Himalayas, or Himalaya ( ), is a mountain range in Asia, separating the plains of the Indian subcontinent from the Tibetan Plateau. The range has some of the Earth's highest peaks, including the highest, Mount Everest. More than 100 pea ...
n people, the golden langur was first brought to the attention of the Western world by the naturalist Edward Pritchard Gee in the 1950s. Adult males have a
cream Cream is a dairy product composed of the higher-fat layer skimmed from the top of milk before homogenization. In un-homogenized milk, the fat, which is less dense, eventually rises to the top. In the industrial production of cream, this proces ...
to golden coat with darker flanks while the females and juveniles are lighter. The golden langur has a black face and a long tail up to in length. It lives in high trees and has a
herbivorous A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat n ...
diet of fruits, leaves, seeds, buds, and flowers. The average group size is eight individuals, with a ratio of several females to each adult male. It is one of the most endangered primate species of India and Bhutan. In 2008–09, there were 6,000 golden langurs in India, which has grown to 7,396 by 2020–21.


Discovery and etymology

The earliest record of the golden langur is in an 1838 paper by Robert Boileau Pemberton which states that "Griffith observed these monkeys near Tongso in Central Bhutan." However, since Pemberton's work was lost and not rediscovered until the 1970s, the scientific discovery of the golden langur unfolded differently. In 1907,
Edward Oswald Shebbeare Edward Oswald Shebbeare (3 March 1884 – 11 August 1964) was a British mountaineer, naturalist and forester who served in the Imperial Forest Service. He was a member of the 1924 British Mount Everest expedition and the deputy leader and tra ...
—who was out with some hunters and forest rangers—reported seeing a "cream coloured langur" in the vicinity of the Jamduar. However, neither a photograph nor a live or dead specimen was presented at that time. The first reference to the golden langur in print, as an animal of unidentified taxonomic status, was in a 1919 publication that stated: "'' Pithecus'' sp? – A pale yellow coloured langur is common in the adjoining district of Goalpara (Assam). Jerdon reported one from
Terai The Terai or Tarai is a lowland region in parts of southern Nepal and northern India that lies to the south of the outer foothills of the Himalayas, the Sivalik Hills and north of the Indo-Gangetic Plain. This lowland belt is characterised by ...
, the adjacent district on the (west) side, which Blanford suggested might be ''P. entellus''." In February 1947, in the Forest Rest House visitors' book in Raimona, a few miles south of Jamduar, C. G. Baron reported seeing some langurs whose "whole body and tail is one colour – a light silvery-gold, somewhat like the hair of a blonde." A year later, back in Jamduar, H. E. Tyndale, a tea planter, reported seeing "Sankosh cream langurs." However, it wasn't until a few years later that a focused effort to identify the golden langur was mounted by Gee, who traveled back to Jamduar in November 1953. His team was able to observe three groups of golden langurs, all on the east bank of the Sankosh River. The first group was observed on the Bhutan side of the border; the second group, a large one of 30 to 40 individuals, a mile north of Jamduar on the Indian side; and a third group four to five miles (6.44 km to 8.05 km) south near Raimona. Colour movies of the second group were made by Gee. In August 1954, Gee reported his findings to an expert at the
Zoological Society of London The Zoological Society of London (ZSL) is a charity and organization devoted to the worldwide animal conservation, conservation of animals and their habitat conservation, habitats. It was founded in 1826. Since 1828, it has maintained London Zo ...
, who advised that the golden langur might be a new species. In January 1955, Gee also reported his results to the
Zoological Survey of India The Zoological Survey of India (ZSI), founded on 1 July 1916 by the Ministry of Environment, Forest and Climate Change of the Government of India as a premier Indian organisation in zoological research and studies to promote the survey, explora ...
(ZSI) and, after showing his movies of the golden langurs, suggested that Jamduar be included in the then-upcoming ZSI survey of that region. The suggestion received the support of Dr.
Sunder Lal Hora Sunder Lal Hora (22 May 1896 – 8 December 1955) was an Indian ichthyologist known for his biogeographic theory on the affinities of Western Ghats and Indomalayan fish forms. Life Hora was born at Hafizabad in the Punjab (modern da ...
, then Director of ZSI, and later that year six specimens of the golden langur were collected by the survey party. The following year, Dr. H. Khajuria, a taxonomist who studied the specimens, described the new species naming it ''Presbystis geei'' in honour of Gee.


Taxonomy

There are two subspecies of this species: * ''Trachypithecus geei geei'' Khajuria, 1956 * ''Trachypithecus geei bhutanensis'' Wangchuk, 2003 The subspecies are separated by a geological fault in the Himalayas called the Main Frontal Thrust. ''T. g. bhutanensis'' occurs in the northern part of the species range in Bhutan and ''T. g. geei'' is found in the south of Bhutan and Assam in northern India. In Bhutan, it has hybridised with '' T. pileatus'', the capped langur. This is believed to be due to the construction of permanent bridges across the Chamkar River, a tributary of the Mangde River which separates the two species.


Physical description

In online viral imagery of this species, many commentators have noted that its uncanny gaze appears remarkably human. This is likely due to the light
sclera The sclera, also known as the white of the eye or, in older literature, as the tunica albuginea oculi, is the opaque, fibrous, protective outer layer of the eye containing mainly collagen and some crucial elastic fiber. In the development of t ...
in its eyes, a feature seen in some
great apes The Hominidae (), whose members are known as the great apes or hominids (), are a taxonomic family of primates that includes eight extant species in four genera: '' Pongo'' (the Bornean, Sumatran and Tapanuli orangutan); '' Gorilla'' (the ...
, including
humans Humans (''Homo sapiens'') or modern humans are the most common and widespread species of primate, and the last surviving species of the genus ''Homo''. They are Hominidae, great apes characterized by their Prehistory of nakedness and clothing ...
. The coat of the adult golden langur ranges from cream to golden, on its flanks and chest the hairs are darker and often
rust Rust is an iron oxide, a usually reddish-brown oxide formed by the reaction of iron and oxygen in the catalytic presence of water or air moisture. Rust consists of hydrous iron(III) oxides (Fe2O3·nH2O) and iron(III) oxide-hydroxide (FeO(OH) ...
coloured while the coats of the juveniles and females are lighter, silvery white to light buff. The coat changes color seasonally, from white or cream coloured in the summer to dark golden or chestnut in the winter. Their long whiskers protect their eyes from rain during
monsoon A monsoon () is traditionally a seasonal reversing wind accompanied by corresponding changes in precipitation but is now used to describe seasonal changes in Atmosphere of Earth, atmospheric circulation and precipitation associated with annu ...
. The golden langur has a black face and a large whorl of hair on its crown. Gee's golden langur exhibits
sexual dimorphism Sexual dimorphism is the condition where sexes of the same species exhibit different Morphology (biology), morphological characteristics, including characteristics not directly involved in reproduction. The condition occurs in most dioecy, di ...
. Males are larger and more robust than females. Adult males weigh on average and adult females weigh . The length of the head and body ranges from , while the relatively long tail is in length.


Distribution

Gee's golden langur is found in an area of approximately , much of which is unsuitable habitat, bounded on the south by the
Brahmaputra River The Brahmaputra is a trans-boundary river which flows through Southwestern China, Northeastern India, and Bangladesh. It is known as Brahmaputra or Luit in Assamese language, Assamese, Yarlung Tsangpo in Lhasa Tibetan, Tibetan, the Siang/Dihan ...
, on the east by the Manas River, on the west by the Sankosh River, in
Assam Assam (, , ) is a state in Northeast India, northeastern India, south of the eastern Himalayas along the Brahmaputra Valley, Brahmaputra and Barak River valleys. Assam covers an area of . It is the second largest state in Northeast India, nor ...
,
India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...
, and on the north by the Black Mountains of
Bhutan Bhutan, officially the Kingdom of Bhutan, is a landlocked country in South Asia, in the Eastern Himalayas between China to the north and northwest and India to the south and southeast. With a population of over 727,145 and a territory of , ...
. These biogeographical barriers are believed to have led to the radiation of species from the closely related capped langur (''Trachypithecus pileatus''). There are two primary sub-populations fragmented by the National Highway 27. The northern sub-population occupies the western portion of the
Manas National Park Manas National Park is a national park, Project Tiger reserve, and an elephant reserve in Assam, India. Located in the Himalayan foothills, it borders the Royal Manas National Park in Bhutan. The park is known for its rare and endangered ende ...
, extending from the Sankosh River to the Manas River along the northern side of National Highway 27 and State Highway 2, reaching the India-Bhutan border. Conversely, the southern sub-population is situated along the southern side of NH27, extending to the Brahmaputra River. Population estimates of the 2020–21 survey, indicate a larger northern population, totaling 5,566 individuals distributed across 534 groups and 23 lone males. In contrast, the southern fragmented population consists of approximately 1,830 langurs organized into 173 groups and eight lone males. Notably, the Ripu Reserve Forest hosts the highest number (2,847 individuals) within the northern sub-population, while the Chakrashila Wildlife Sanctuary in Kokrajhar district harbors the most significant number (838 individuals) within the southern fragmented range. In 1988, two captive groups of Gee's golden langur were released into the wild in
Tripura Tripura () is a States and union territories of India, state in northeastern India. The List of states and union territories of India by area, third-smallest state in the country, it covers ; and the seventh-least populous state with a populat ...
state in north-eastern India, an area outside of their natural range. One of the groups, released into Sepahijala Wildlife Sanctuary, survives and has adapted to the wild.


Behavior and ecology

For the most part, the
langur The Colobinae or leaf-eating monkeys are a subfamily of the Old World monkey family that includes 61 species in 11 genera, including the black-and-white colobus, the large-nosed proboscis monkey, and the gray langurs. Some classifications split ...
is confined to high trees where its long tail serves as a balancer when it leaps across branches. During the rainy season it obtains water from dew and rain-drenched
leaves A leaf (: leaves) is a principal appendage of the stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, ...
. Its diet is
herbivorous A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat n ...
, consisting of ripe and unripe
fruit In botany, a fruit is the seed-bearing structure in flowering plants (angiosperms) that is formed from the ovary after flowering. Fruits are the means by which angiosperms disseminate their seeds. Edible fruits in particular have long propaga ...
s, mature and young leaves, seeds, buds and
flower Flowers, also known as blooms and blossoms, are the reproductive structures of flowering plants ( angiosperms). Typically, they are structured in four circular levels, called whorls, around the end of a stalk. These whorls include: calyx, m ...
s. It generally lives in troops of about 8, with a ratio of several females to each adult male. The smallest golden langur troop was composed of four individuals, while the largest had 22, giving an average value of 8.2 individuals per troop. The adult sex ratio was 2.3 females to every male, although the majority of groups had only one adult male.


Conservation

Gee's golden langur is currently
endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching, inv ...
with a decreasing population trend; the total population of mature adults has been estimated as 6000–6500. It is one of the most endangered primate species of India and Bhutan. In India, 93% of the population is found in forest reserves (Chirang, Manas, and Ripu) and the western part of
Manas National Park Manas National Park is a national park, Project Tiger reserve, and an elephant reserve in Assam, India. Located in the Himalayan foothills, it borders the Royal Manas National Park in Bhutan. The park is known for its rare and endangered ende ...
, and the remaining occur in several small isolated fragments. The population has declined by more than 30% in the last 30 years and is expected to decline further shortly. Golden langurs are protected by law in their range. The species is listed in Appendix I of
CITES CITES (shorter acronym for the Convention on International Trade in Endangered Species of Wild Fauna and Flora, also known as the Washington Convention) is a multilateral treaty to protect endangered plants and animals from the threats of inte ...
, and in Schedule I of both, the Wildlife Protection Act, 1972 of India, and the Forest and Nature Conservation Act of Bhutan, 1995.


Within India

On 5 June 2019, the district authorities of Bongaigaon district in
Assam Assam (, , ) is a state in Northeast India, northeastern India, south of the eastern Himalayas along the Brahmaputra Valley, Brahmaputra and Barak River valleys. Assam covers an area of . It is the second largest state in Northeast India, nor ...
launched a project under the MGNREGA to plant guava, mango, blackberry and other fruit trees to ensure that the resident golden langurs of the Kakoijana reserved forest do not have to risk their lives to find food. Several golden langurs have died due to electrocution and in road accidents while looking for food beyond the reserve forests. In 1988, two captive groups of golden langurs were released into two protected areas of the western region of the state of
Tripura Tripura () is a States and union territories of India, state in northeastern India. The List of states and union territories of India by area, third-smallest state in the country, it covers ; and the seventh-least populous state with a populat ...
, India. As of 2000, one of these groups, consisting of six (and possibly eight) individuals in the Sepahijala Wildlife Sanctuary, had survived. The relative death of infants and juveniles indicates a declining population with the habitat being degraded by human activity. A fragmented but protected population in a rubber plantation in the Nayakgaon, Kokrajhar, district of Assam increased in population from 38 individuals in 1997 to 52 in 2002. The population has also adapted to feeding on dry rubber seeds.


Notes


References


Literature cited

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External links

*ARKive �
images and movies of the golden langur (''Trachypithecus geei'')



Golden langur (''Trachypithecus geei'') video clips from the BBC archive
{{Taxonbar, from=Q284104 Gee's golden langur Primates of South Asia Mammals of Bhutan Mammals of India Fauna of Assam Lower Assam Monkeys in India Gee's golden langur Endangered fauna of Asia