Sunday 19 May
Proboscis monkey (Nasalis larvatus)
What’s the World’s Favourite Species?Find out here.
Proboscis monkey fact file
- Find out more
- Print factsheet
Proboscis monkey description
The proboscis monkey has one of the most unusual appearances of any of the leaf-eating monkeys of the family Cercopithecidae. Both the Latin and common names of this species refer to the mature males' large pendulous nose that hangs down over their mouth (4). Local people referred to these large monkeys with their potbellies and red noses as 'Dutch monkeys' as they were considered such a caricature of the Dutch sailors and plantation owners of the area (4). Apart from their large noses, male proboscis monkeys are also distinctive by being much larger and heavier than females, and having a bright red, visible penis and black scrotum (2) (5). The coat is a light brown with red on both the crown of the head and the shoulders; the limbs and tail are grey in colour and there are cream patches on the throat (5). Infants are born with black fur and a vivid blue face (4). The cause of the males' large nose is still a matter of contention but may be a form of sexual selection, with females preferring males with large noses possibly as these enhance their vocalisations (4).
- Mono Narigudo.
- Male head-body length: 73 – 76 cm (2)
- Female head-body length: 54 – 64 cm (2)
- Male tail length: 66 – 75 cm (2)
- Female tail length: 52 – 62 cm (2)
- Male weight: 16 – 22 kg (2)
- Female weight: 7 – 12 kg (2)
Proboscis monkey biology
Only a few studies on this intriguing primate have been carried out and little is known about their ecology and behaviour (4). Groups consist of single mature males and around 6 females and their young; adolescent males form bachelor groups until they can take over their own harem (4). Groups join together in larger more fluid troops to rest at dusk (5); these encounters may be noisy with rival males displaying to each other and often crashing through the branches (4). Unusually, females may switch harems several times in their lives (4), and they compete between each other to mate with the male of their group. When a female is ready to mate she will perform a head shaking and presenting display (5). A single offspring is born after a gestation period of nearly 6 months, remaining with their mother for the first few years (4); males will then leave to join bachelor groups (5).
Young leaves make up the majority of the proboscis monkey diet between June and December, and fruit from January to May (2), although seeds and flowers are also consumed (7). These monkeys are excellent swimmers and have partially webbed feet; they can be seen readily leaping into the water with a dramatic belly flop in order to cross rainforest rivers (4).Top
Proboscis monkey rangeTop
Proboscis monkey habitat
Proboscis monkeys are found in either coastal mangrove forests or in lowland rainforest close to freshwater rivers (7).Top
Proboscis monkey statusTop
Proboscis monkey threats
Numbers of proboscis monkeys in Borneo have fallen dramatically in the last 40 years primarily as a result of habitat loss (4). Vast areas of the native rainforest have been cleared for timber and for the construction of oil-palm plantations, which now constitute one of Malaysia's top exports (4). Proboscis monkeys do not adapt to degraded habitat and recent technical advances have meant that even mangrove swamps may now be logged (4). Hunting is also a threat to the survival of this species; their propensity to gather in large groups on the river's edge makes these monkeys easy targets (4).Top
Proboscis monkey conservation
The proboscis monkey is protected by law (4), and is listed on Appendix I of the Convention on International Trade in Endangered Species (CITES), banning international trade (3). This species is found in at least a dozen protected areas (2). Recently, a vital area of wetland in Sabah has been designated as a sanctuary for a wide range of endangered species such as Asian elephants (Elephas maximus) and orang-utans (Pongo pygmaeus) as well as proboscis monkeys; this area is the Kinabatangan Wildlife Sanctuary (4). However, even this corridor is currently fragmented by plantations, which proboscis monkeys cannot cross (4). The protection of remaining tracts of contiguous habitat is therefore vital for the survival of this unusual looking monkey.Top
Find out more
For more information on this species see:
Primate Info Net:
Authenticated (09/01/2006) by Matt Richardson, independent primatologist and writer.Top
- A species or taxonomic group that is only found in one particular country or geographic area.
IUCN Red List (April, 2003)
- Richardson, M. (2006) Pers. comm.
CITES (April, 2003)
- Buckley, M. (2002) Last of the high-flyers. BBC Wildlife Magazine, 20(2): 34 - 42.
Primate Info Net (April, 2003)
- Macdonald, D. (2001) The New Encyclopedia of Mammals. Oxford University Press, Oxford.
Animal Diversity Web (April, 2003)
MyARKive offers the scrapbook feature to signed-up members, allowing you to organize your favourite ARKive images and videos and share them with friends.
Terms and Conditions of Use of Materials
Copyright in this website and materials contained on this website (Material) belongs to Wildscreen or its licensors.
Visitors to this website (End Users) are entitled to:
- view the contents of, and Material on, the website;
- download and retain copies of the Material on their personal systems in digital form in low resolution for their own personal use;
- teachers, lecturers and students may incorporate the Material in their educational material (including, but not limited to, their lesson plans, presentations, worksheets and projects) in hard copy and digital format for use within a registered educational establishment, provided that the integrity of the Material is maintained and that copyright ownership and authorship is appropriately acknowledged by the End User.
End Users shall not copy or otherwise extract, alter or manipulate Material other than as permitted in these Terms and Conditions of Use of Materials.
Additional use of flagged material
Green flagged material
Certain Material on this website (Licence 4 Material) displays a green flag next to the Material and is available for not-for-profit conservation or educational use. This material may be used by End Users, who are individuals or organisations that are in our opinion not-for-profit, for their not-for-profit conservation or not-for-profit educational purposes. Low resolution, watermarked images may be copied from this website by such End Users for such purposes. If you require high resolution or non-watermarked versions of the Material, please contact Wildscreen with details of your proposed use.
Creative commons material
Certain Material on this website has been licensed to Wildscreen under a Creative Commons Licence. These images are clearly marked with the Creative Commons buttons and may be used by End Users only in the way allowed by the specific Creative Commons Licence under which they have been submitted. Please see http://creativecommons.org for details.
Any other use
Please contact the copyright owners directly (copyright and contact details are shown for each media item) to negotiate terms and conditions for any use of Material other than those expressly permitted above. Please note that many of the contributors to ARKive are commercial operators and may request a fee for such use.
Save as permitted above, no person or organisation is permitted to incorporate any copyright material from this website into any other work or publication in any format (this includes but is not limited to: websites, Apps, CDs, DVDs, intranets, extranets, signage, digital communications or on printed materials for external or other distribution). Use of the Material for promotional, administrative or for-profit purposes is not permitted.