Predation of black crested gibbons has not been well characterized.
Male black crested gibbons are black, while females are a tawny buff color. Females have a black crown and typically have black hair grizzling or covering the lower chest and abdomen (Mootnick and Fan 2011). This sexual dichromatism develops with age, as the female changes from black to buff or tawny coloration in early adulthood (Mootnick and Fan 2011). Black crested gibbons generally weigh from 6.9 to 10 kg (average 8 kg) and measure between 43 and 54 cm (average 50 cm) (Ma et al. 1988).
Range mass: 6.9 to 10 kg.
Range length: 43 to 54 cm.
Sexual Dimorphism: sexes colored or patterned differently
Other Physical Features: endothermic ; bilateral symmetry
Black crested gibbons are believed to have similar longevity to other gibbons, which is estimated to be 25 to 30 years.
Black crested gibbons live in evergreen, semi-evergreen, and deciduous forests in subtropical and mountainous areas (Geissmann and Orgeldinger 2000; Jiang et al. 2006). They are primarily observed at altitudes ranging from 2100 to 2400 m above sea level, where most of their food resources are concentrated (Fan and Jiang 2010). However, in Vietnam, black crested gibbons were observed living at altitudes from 1600 to 2000 m (Dao Van Tien 1985) and in Laos, from 550 to 900 m (Geissmann 2007). Black crested gibbons have been observed at altitudes as high as 2689 m (Fan and Jiang 2010).
Range elevation: 550 to 2689 m.
Habitat Regions: tropical ; terrestrial
Terrestrial Biomes: rainforest
Black crested gibbons communicate through vocalizations, including calls and songs, as well as physical interactions and facial expressions. The songs of black crested gibbons may be used for a variety of purposes, including defense of resources and establishment of territories (Sun et al. 2011), as well as attracting mates and strengthening pair bonds (Geissmann and Orgeldinger 2000). Black crested gibbons sing both alone and in pairs. Duets are usually initiated by males from high locations, such as tall trees on hills. Duets may play a part in mate attraction or pair-bonding between mates, defense of resources or mates, or group cohesion (Fan et al. 2009).
Communication Channels: visual ; tactile ; acoustic
Other Communication Modes: duets
Perception Channels: visual ; tactile ; acoustic ; chemical
Black crested gibbons are considered critically endangered by the IUCN (2010). Deforestation due to the steel industry, military activity during political unrest, and later to farming has greatly reduced viable habitat, threatening populations of black crested gibbons (Jiang et al. 2006). Although forests have been allowed to regenerate in some areas, in many others, farming has become permanent or invasive plant species have prevented forest regeneration (Jiang et al. 2006). Additionally, separation of small groups of this species due to habitat destruction may lead to decreased gene flow, further endangering the species (Jiang et al. 2006).
Hunting contributed to the extirpation of black crested gibbons in areas of Wuliang (Jiang et al. 2006). Although no reports of poaching have occurred since 1994, even low rates of hunting are projected to carry the risk of local extinction (Seal 1994).
US Federal List: endangered
CITES: appendix i
IUCN Red List of Threatened Species: critically endangered
There are no known adverse effects of black crested gibbons on humans.
Black crested gibbons can be found in some zoos worldwide. Although now restricted, hunting once contributed considerably to the decline of black crested gibbons.
Because they consume a considerable amount of fruit, black crested gibbons likely act as seed dispersers. They also act as hosts to a variety of nematodes, roundworms, and other parasites, including Dirofilaria digitata, Probstmayria gorillae, Streptopharagus pigmentatus, Streptopharagus sandgroundi, and Dipetalonema digitatum.
Ecosystem Impact: disperses seeds
Commensal/Parasitic Species:
In Yunnan, China, black crested gibbons are folivorous-frugivorous, spending on average similar amounts of time eating leaves and fruit. Their diet varies seasonally, based on the availability of food sources including leaves, fruits, buds, and flowers. In a study in 2008 (Fan et al.), black crested gibbons ate increased levels of figs in August and September, flowers in February and April, leaves in March, and buds and leaves in December and January. They prefer to eat fruits and figs over other foods during their first and last meals of the day (Fan et al. 2008). They have also been observed eating insects, eggs, and other small organisms. One population of black crested gibbons concentrated ranging behavior, staying in valleys with more abundant food for several consecutive days before moving to another, in order to avoid frequent passages through areas with little food (Fan and Jiang 2008).
Animal Foods: birds; mammals; reptiles; eggs; insects
Plant Foods: leaves; fruit; flowers
Primary Diet: herbivore (Folivore , Frugivore )
Black crested gibbons, Nomasus concolor, are primarily found in Yunnan, China and have restricted ranges in western Laos and northern Vietnam (Geissmann and Orgeldinger 2000). Their distribution is discontinuous, with populations occurring between the Black and Red Rivers in southern China (Nomascus concolor concolor), near the China-Myanmar border (Nomascus concolor furvogaster), between the Mekong and and Chuanghe Rivers (Nomascus concolor jingdongensis), and in northwestern Laos (Nomascus concolor lu) (Groves 2001).
Biogeographic Regions: oriental (Native )
Black crested gibbons live in family units generally consisting of a monogamous male and female and their offspring. Although most black crested gibbons are monogamous, occasionally two females in a single breeding group are tolerated (Jiang et al. 1999). Polygyny has not been observed in other species of gibbons.
Singing may play a role in mate attraction, pair-bonding, and mate defense of black crested gibbons (Geissmann and Orgeldinger 2000; Fan et al. 2009).
Mating System: monogamous ; polygynous
Black crested gibbons reproduce once every 2 to 3 years, usually producing one offspring in each interval. The gestation period lasts about 7 to 8 months, and newborns weigh about 510 g at birth (Geissmann and Orgeldinger 1995). Offspring are weaned around 2 years of age, and they reach sexual maturity at about 8 years of age.
Breeding interval: Black crested gibbons reproduce once every 2 to 3 years.
Average number of offspring: 1.
Range gestation period: 7 to 8 months.
Average age at sexual or reproductive maturity (female): 8 years.
Average age at sexual or reproductive maturity (male): 8 years.
Key Reproductive Features: gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
Young black crested gibbons are nursed by their mother until about 2 years of age. Males and older offspring also provide care to young.
Parental Investment: female parental care ; pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female)
The black crested gibbon (Nomascus concolor) is a Critically Endangered species of gibbon found in China, Laos, and northern Vietnam, with four subspecies.
The taxonomy of the species is confused. Previously grouped in the genus Hylobates, currently four subspecies are recognised.[3]
The length from the head to the end of body is 43–54 cm (17–21 in) and it weighs from 6.9 to 10 kg (15 to 22 lb).[5] The species exhibits sexual dichromatism, the male is completely black, while the female is a golden or buff colour with variable black patches, including a black streak on the head.[5]
Gibbons are forest dwellers and are well known for their habit of swinging between the branches of the rainforest on their long arms, a method of locomotion known as brachiation. Gibbons are also adept, however, at walking upright, both on the ground and in the trees. Black crested gibbons live in small family groups consisting of a monogamous male and female and their offspring; occasionally groups reportedly may contain additional mature females. These apes are predominantly arboreal and the group forages and sleeps amongst the trees. Led by the female, the breeding pair partakes in vigorous bouts of singing in the morning, which hauntingly echo through the forest. These 'duets' are believed to be essential in pair bond formation and reinforcement, and also serve to advertise the presence of the group within the territory. A single young is born every two to three years and the infant is usually weaned once it reaches two years old;
Black crested gibbons feed preferentially on ripe, sugar-rich fruit, such as figs, but occasionally consume vitamin-rich leaf buds, and rarely eat animals.
Black-crested gibbons live arboreally in small groups, most of which consist of a pair of adults, one male and one female, and their offspring. It has been observed that some groups consist of one adult male living with two to four females and their offspring. The group could potentially include one infant, one juvenile, one adolescent, and one sub adult.[6] Groups have been found to be territorial, like other species of gibbons. Territories are limited by the availability of the male for territory defense. Thus, group and territory size would be limited. With a large group, territory defense would not be favored by kin selection due to the group consisting of less-closely related individuals.[7] Though the research is not explicit, there can be some assumptions made about altruism within groups. Since the majority of groups are living in monogamous relationships with both males and females displaying aggression when another individual enters,[7] it is likely that kin selection plays a major role in determining behavior of the group. Kin recognition is thought to be favored for maternal-offspring relationships. This is largely due to primates' uncertainty over paternity, even in pair-bonding species due to female promiscuity.[8] Social behaviors within groups will evolve according to Hamilton's rule.[9]
Gibbons were previously reported to practice monogamous sexual relationships.[7] They are known to form pair bonds, as well documented in the majority of gibbon species.[8] Upon the discovery of single male, multi-female living groups, the question arose to determine if all females were mating. The observation that offspring of similar ages lived within a multi-female group confirmed that polygyny did in fact occur. The current hypothesis remains that both monogamous and polygamous relationships exist.[6] There may be various selection pressures for polygyny within previously monogamous groups. Parents tend to be hostile towards maturing offspring, with males leaving the group more quickly than females do.[6] Yet, upon tolerance by the mother, adult female offspring may remain in the group, as the group continues to forage and feed as family members. The mutual tolerance of females is likely to be caused by "weak territoriality of females".[6] Further selection occurs due to the birth interval for a single female averaging 2–2.5 years. Male fitness would benefit from inseminating other females during a birth interval.[6] This hypothesis is supported by the large scrotal size allowing for increased sperm production.[6] Other observations have been made that males will share child carrying to place less of a burden on the female, delaying her interbirth time.[7] The conflicting observations support the hypothesis that black-crested gibbons demonstrate both monogamous and polygamous sexual relationships.
All gibbon species are known to produce loud and long song bouts, lasting for 10–30 minutes. The black-crested gibbon sings in the morning, sometimes in duets initiated by the male. The males choose the highest tree branches, often near ridges. The songs are thought to be used for resource defense, mate defense, pairbonding, group cohesion and mate attraction.[10]
The black crested gibbon has a discontinuous distribution across southwestern China, northwestern Laos, and northern Vietnam. One thousand years ago, gibbons which may have been crested gibbons (Nomascus) were found over a large part of southern and central China up to the Yellow River.[3]
The four subspecies are geographically separated. The Tonkin black crested gibbon (Nomascus concolor concolor) occurs in southern China (southwestern Yunnan) and northern Vietnam (Lào Cai, Yên Bái, Sơn La, and Lai Châu provinces), between the Black and Red Rivers. The West Yunnan black crested gibbon (N. c. furvogaster) occurs in a small area near the Burma border, west of the Mekong, in southwestern Yunnan, southern China. The Central Yunnan black crested gibbon (N. c. jingdongensis) occurs in a small region around the Wuliang Mountains, between the Mekong and Chuanhe rivers in west-central Yunnan. The Laotian black crested gibbon (N. c. lu) occurs in northwestern Laos in an isolated population on the east bank of the Mekong in Laos.[3]
The black crested gibbon inhabits tropical evergreen, semievergreen, deciduous forests in subtropical and mountainous areas. It generally lives in high altitudes, from 2100 to 2400 m above sea level, where most of their food resources are concentrated. In Vietnam and Laos, the species is found at lower altitudes, while in China, it has been observed as high as 2689 meters.[5]
The black crested gibbon is listed as critically endangered on the IUCN Red List. An estimated 1300 to 2000 individuals are left in the wild.[3] The western black crested gibbons were included on the State Forestry Bureau of China's list of 12 flagship and keystone species for biodiversity protection in 2021.[11] While under protection, there was still a noticeable decline in population size at Wuliangshan National Nature Reserve.[12] It was discovered that the gray langurs are suppressing the black crested gibbon's potential recovery.[12] The gray langurs and black crested gibbons have similar diets and ranges; however, gray langurs have an advantage by having a more comprehensive dietary list, a larger group, and faster life history.[13] The black crested gibbon inhabits the evergreen broad-leaved forests that take a long time to regenerate, making it challenging for the gibbons to connect with other groups.[14] Ecological corridors were put in place in the Hengduan Mountain in China to help restore connections between different groups, increase overall well-being, and decrease the risk of extinction.[15]
The black crested gibbon (Nomascus concolor) is a Critically Endangered species of gibbon found in China, Laos, and northern Vietnam, with four subspecies.
