The 'Proboscis Monkey' (''Nasalis larvatus''), also known as the 'Long-nosed Monkey', is a reddish-brown
arboreal Old World monkey. It is the only species in monotypic genus '''Nasalis'''.
Appearance
The most distinctive trait of this
monkey is the male's large protruding
nose. The purpose of the large nose is unclear, but it has been suggested that it is a result of
sexual selection. The female Proboscis Monkey prefers big-nosed male, thus propagating the trait.
Males are much larger than females, reaching 72
cm (28
inches) in length, with an up to 75 cm tail, and weighing up to 24
kg (53
pounds). Females are up to 60 cm long, weighing up to 12 kg (26 lb).
The Proboscis Monkey also has a large belly, as a result of its diet. Its
digestive system is divided into several parts, with distinctive gut flora, which help in digesting
leaves. This digestive process releases a lot of
gas, resulting in the monkey's "bloated" bellies. A side-effect of this unique digestive system is that it is unable to digest ripe
fruit, unlike most other
simians. The diet consists mainly of fruits, seeds and leaves.
Ecology
The Proboscis Monkey is distributed and
endemic to the coastal
mangrove,
swamps and
riverine forests of
Borneo. It lives in small groups of 10 to 32 animals. Group membership is very flexible, and animals are known to move from group to group quite often.
The Proboscis Monkey lifestyle is both arboreal and amphibious, with its mangrove swamp and riverine environment containing forest, dry land, shallow water allowing wading, and deep water requiring swimming. Like other similar monkeys, the Proboscis Monkey climbs well. It is also a proficient swimmer, often swimming from island to island, and has been picked up by fishing boats in open ocean a mile from shore. While wading, the monkey uses an upright posture, with the females carrying infants on their hip. Troops have been filmed continuing to walk upright, in single file, along forest trails when they emerge on land, the only non-human mammal, with the exception of
gibbons and
giant pangolins, known to use this form of locomotion for any length of time.
Status
Due to ongoing habitat lost and hunted in some areas, only about 7000 are known to still exist in the wild. In
Sarawak, the population of this species has declined from 6500 in 1977 to only 1000 in 2006. The Proboscis Monkey is evaluated as Endangered on the
IUCN Red List of Threatened Species. It is listed on Appendix I of
CITES.
Other names
While the official Indonesian name for this monkey is 'Bekantan', an
Indonesian nickname is 'monyet belanda', meaning 'Dutch monkey' or 'Orang Belanda', the Indonesian word for 'Dutchman', as Indonesians noticed the
Dutch colonisers often also had a large belly and nose.
References
★ Listed as Endangered (EN A2c, C1+2a v2.3)
★
External links
★ ARKive -
images and movies of the Proboscis monkey ''(Nasalis larvatus)''
★
Primate Info Net ''Nasalis'' Factsheets
★
Save the Proboscis Monkeys Petition and weblog with info on the rare, endangered species.