According to the criteria set by the IUCN Red List, all species of gibbon are regarded as threatened.
Gibbons seem to receive far less attention than the other members of the ape family, but it doesn't mean gibbons are not worth protecting.
The smallest of the apes, gibbons are often referred to as 'lesser apes'. They are found only in the Indo-Malayan region, extending from India and China, down through mainland Southeast Asia and into Indonesia. Living in small family groups, gibbons are mostly monogamous. The pair will often stay together for life, defending a patch of forest that provides for all of their needs, and raising their young, with up to four offspring remaining with the family at any one time.
Acrobats of the forest, a gibbons long arms and compact body are perfectly adapted for life in the trees, so they need never come to the ground and generally live an entirely arboreal existence. So well adapted to a life in the canopy, they are capable of performing leaps between trees of up to 12 m and brachiating at speeds of up to 56 km/h.
Gibbons communicate with a wide repertoire of vocalisations, but are best known for their hauntingly beautiful song; males and females sing together in a duet that is unique to each species. They are relatively slow breeders, giving birth to only one offspring every 3-4 years, and baby gibbons remain fully dependant on their mother for around 12 months. By the age of 2 years they begin to move independently from their mother. A young gibbon has a lot to learn, and stays with its parents until around 5-6 years of age, reaching full maturity at around 8 years. Gibbons eat mainly fruit and supplement this diet with leaves and insects.
There are currently 4 genera and 19 species of gibbons recognized throughout their range. In Vietnam we have 6 of the 7 species in the genus Nomascus, otherwise known as the crested gibbons. Crested gibbons are similar in size, averaging around 60cm head-body length and 7.5kg in weight. They are distinct from the other gibbon groups by the obvious crest of fur on the crown of males, and their colouration, with males being black with white or orange cheeks and females being golden. All the crested gibbons are born yellow, but change colour with age.
See the diagram below for the color and behavior change with age in crested gibbons.
Being almost exclusively arboreal, gibbons are fully dependent on intact forests. When these forests are fragmented, gibbon populations decline due to lack of food, social opportunities and gene flow. In addition, fragmented forests allow easier access, exposing already declining gibbon populations to illegal hunting. An arboreal fruit eater, these increasingly rare primates play a key role as seed dispersers in the Indo Malayan forests. Their decline in these forests will undoubtedly impact on the biodiversity and the ability of the forests to regenerate.
In addition to habitat fragmentation, gibbon species in Vietnam are under extremely heavy hunting pressure from poachers who make a profit out of selling gibbons for the production of traditional medicine, food, and more commonly, the pet trade.
According to the criteria set by the IUCN Red List, all species of gibbon are regarded as threatened. Of all the gibbons, the crested gibbons are the most threatened with 5 of the 7 species listed as Critically Endangered.