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 )

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

• Terrestrial

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

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 )

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:

• Dirofilaria digitata
• Probstmayria gorillae
• Streptopharagus pigmentatus
• Streptopharagus sandgroundi
• Dipetalonema digitatum

Predation of black crested gibbons has not been well characterized.

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 ; acoustic

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 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 birth mass: 510 g.

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); 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)

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.