Hose’s langur (Presbytis hosei)

Also known as: grey langur, grey leaf monkey, grey sureli, Hose’s leaf monkey
  
French: Semnopithèque De Hose
Spanish: Langur De Hose
KingdomAnimalia
PhylumChordata
ClassMammalia
OrderPrimates
FamilyCercopithecidae
GenusPresbytis (1)
SizeHead-and-body length: 48 – 56 cm (2)
Tail length: 65 – 84 cm (2)
Average male weight: 6 – 7 kg (3)
Average female weight: 5.5 – 6 kg (3)

Classified as Vulnerable (VU) on the IUCN Red List (1) and listed under Appendix II of CITES (4). Four subspecies are recognised: Hose’s grizzled langur (P. h. hosei) is classified as Data Deficient (DD), Everett’s grizzled langur (P. h. everetti) is classified as Vulnerable (VU), while the Miller’s grizzled langur (P. h. canicrus) and the crested grizzled langur or saban grizzled langur (P. h. sabana) are classified as Endangered (EN) on the IUCN Red List (1).

Hose’s langur is a relatively small, slim-built primate (5), characterised by a high forehead and a prominent, forward-leaning crest down the centre of the crown (3) (6). The colour of the coat varies with the subspecies, but is predominantly grey on the back, white on the stomach and chest, and blackish on the hands and feet. The face is pink, with a distinct black band marking each cheek. Infants are easily distinguished, being white with black lines down the back and across the shoulders (3). Groups (probably the adult male) sometimes give a unique gargling call (7).

Endemic to the island of Borneo (6), in the countries of Brunei Darussalam, Indonesia (Kalimantan), and Malaysia (provinces of Sarawak and Sabah) (1). P. h. hosei occurs in Sarawak (1), but may only be found around the lower Baram river (3). P. h. everetti is found along the northwest coast of Sabah into Brunei, while P. h. sabana is confined to central and eastern Sabah and south-western to Kalabakan (3). This subspecies may also be found in far north-eastern Kalimantan. P. h. canicrus is recorded definitely only from Gunung Talisayan and Karangan in East Kalimantan, but is probably also present in Kutai (7).

This arboreal monkey largely moves through the middle levels of the forest canopy, occasionally descending to the ground to visit natural mineral sources (3). Primary and, less abundantly, secondary forests are inhabited, in an altitudinal range of 1,000-1300 m. The species will also occasionally enter plantations (3) (7).

Hose’s langur is a diurnal species with a primarily folivorous diet, equipped with a specialised sacculated stomach and enlarged salivary glands to assist in the breakdown of tough leaf material. However, the species will also feed on fruits, seeds and flowers, as well as on the eggs and nestlings of birds such as the gray-throated babbler (Stachyris nigriceps) (3).

In Sabah and Brunei, group sizes tend to range from six to eight individuals, although 12 or more have reported from Temburong and solitary individuals do occur (3) (7). Groups contain one adult male and two or more adult females, and mating is polygynous (3) (7). Hose’s langurs give birth to single offspring (3), which are weaned by one year and fully mature by four to five (5), with males dispersing from their natal groups (7).

Hunting and deforestation pose critical threats to this species across its range. Indeed, the reputed medicinal value of the ‘bezoar’ stones sometimes formed in the monkey’s guts makes this species a target even for hunters uninterested in its meat (6). Interviews with local hunters indicate that hunting for these bezoar stones was the primary reason for the 50 – 80% decline recorded for the species between 1996 and 2003 in Kayan Mentarang National Park, East Borneo, where the forest has remained in fairly pristine condition (8). In this case, a merchant calling at a nearby village in 1998 had reportedly guaranteed to purchase them, sparking excessive hunting of Hose’s langur in the area, to such an extent that 3 years later this hunting was no longer economically viable (8). As a result of habitat loss and hunting pressure, Miller’s grizzled langur (P. h. canicrus) is thought to be critically endangered, or even extinct. Thus, it is listed as one of the world’s 25 most endangered species, although no quantitative surveys have yet been undertaken. Hose’s grizzled langur (P. h. hosei) is considered by many to be in a worse predicament and even more likely to be extinct, although there is a small chance that it exists in the northern part of the Similajau National Park in central coastal Sarawak. Populations may also exist in Brunei, which has suffered much less hunting and deforestation, but hybridization with Everett’s grizzled langur (P. h. everetti) could be a potential issue in this area (6).

Hose’s langur is fully protected in Sarawak, prohibiting individuals from keeping them as pets, or hunting, capturing, killing, selling, importing or exporting them, with stiff penalties of a fine and two years imprisonment if caught (7). The species appears in a few protected areas, such as Kutai National Park and Kayan Mentarang National Park, but the protection offered is frequently inadequate and laws remain unenforced. Indeed, despite being found in national parks, only an estimated 5% of the Kutai National Park forest has escaped logging, illegal settling, industrial development and fire (6), and active protection of Kayan Mentarang National Park has clearly been lacking, having suffered heavily from hunting pressure (8). In such cases, National Park ‘protection’ alone does not guarantee preservation, and more active protection of wildlife against hunting and habitat destruction is desperately required to prevent the extinction of this species. Sadly, it may already be too late for certain subspecies.

For more information on Hose’s langur see:

Authenticated (12/03/2006) by Matthew Richardson, independent primatologist and writer.

  1. IUCN Red List (June, 2009)
    http://www.redlist.org
  2. Richardson, M. (2006) Pers. comm.
  3. The Primata (January, 2006)
    http://www.theprimata.com/presbytis_hosei.html
  4. CITES (November, 2005)
    http://www.cites.org
  5. Paleaorama.com (January, 2006)
    http://www.paleorama.com/Mammals-P/Presbytis.php
  6. Primates in Peril: The World’s 25 Most Endangered Primates 2004 – 2006 (January, 2006)
    http://portals.conservation.org/downloads/storedfile/Document/top252004final.pdf
  7. Forest Department Sarawak (January, 2006)
    http://www.forestry.sarawak.gov.my/forweb/wildlife/mgmt/tpa/tprotsp.htm
  8. Nijman, V. (2005) Decline of the endemic Hose's langur Presbytis hosei in Kayan Mentarang National Park, East Borneo. Oryx, 39: 223 - 226.