Nomascus concolor (Harlan, 1826)
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publication ID |
https://doi.org/ 10.5281/zenodo.6727957 |
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DOI |
https://doi.org/10.5281/zenodo.6757648 |
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persistent identifier |
https://treatment.plazi.org/id/03D787BA-0E30-FFC9-FF04-FE00F8D6CD09 |
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treatment provided by |
Jonas |
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Nomascus concolor |
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12. View Plate 54: Hylobatidae
Western Black Crested Gibbon
French: Gibbon noir / German: Westlicher Schopfgibbon / Spanish: Gibén de cresta negra
Other common names: Black Crested Gibbon, Black Gibbon, Concolor Gibbon, Indochinese Gibbon; Laotian Black Crested Gibbon (/u), Tonkin Black Crested Gibbon (concolor)
Taxonomy. Simia concolor Harlan, 1826 ,
Vietnam, Tonkin.
Up to four subspecies have been recognized. Here, the two forms named by S. Ma and Y. Wang in 1986 (furvogaster from south-western Yunnan west of the Mekong River and jingdonensis found in westcentral Yunnan, China) are considered synonymous with the nominate from, concolor, based on recent genetic evidence. Two subspecies are recognized.
Subspecies and Distribution. N. ¢c. concolor Harlan, 1826 — S China (C & SW Yunnan Province) including a small population W of the Mekong River near the Myanmar border, and N Vietnam (Lao Cai, Son La, and Yen Bai provinces) between the Black and Red rivers from ¢.20° N 023° 45° N. c. c. lu Delacour, 1951 — NW Laos (Bokeo and Luang Namtha provinces) in an isolated population E of the Mekong River at ¢.20° 17° N-20° 25’ N. View Figure
Descriptive notes. Head-body 43-45 cm; weight 7-8 kg. In 1988, Ma and colleagues provided the following measurements: mean head-body of four males and five females, 49-5 cm (range 43-54 cm) and mean weight 7-8 kg (range 6.9-10 kg). As with other species of Nomascus , the Western Black Crested Gibbon is sexually dichromatic; males are completely black with a pronounced crown crest and females are pale yellow through beige brown, often with a darker ventral area that may contrast sharply, and a black cap. Infants are born buff and transition to the same pelage as adult males, which they maintain as juveniles and subadults. Males maintain this pelage color to adulthood, but females change to their adult pelage color as they reach maturity.
Habitat. Semi-humid, montane broadleaf evergreen forest in high elevation subtropical areas. The Western Black Crested Gibbon has been recorded at ¢.500-2900 m above sea level.
Food and Feeding. The Western Black Crested Gibbon probably inhabits an extreme of the hylobatid ecological niche, occupying high elevational seasonal forests. Diet reflects this, with high levels of leaf consumption and low levels of fruit intake compared with other gibbons. Relative frequencies of consumption of food types have been recorded as 46-5% leaves, 25-5% fruit, 18:6% figs, 9-1% flowers, and 0-3% other. High levels of folivory were also recorded in earlier studies, and indeed the Western Black Crested Gibbon has been characterized as a folivore-frugivore. Diet changes markedly throughout the year depending on fruit and fig availability. It has been recorded hunting and feeding on giant flying squirrels (Petaurista philippensis) on Mount Wuliang in China. This was the first record of such behavior in gibbons—now also confirmed for the Northern Yellow-cheeked Crested Gibbon (N. annamensis ). The same group of Western Black Crested Gibbons preys on chicks, eggs, and lizards, and passive food sharing of meat has also been documented.
Breeding. There is no information available for this species.
Activity patterns. The Western Black Crested Gibbon is diurnal and arboreal. Activity begins just before dawn; often commences with loud vocalizations. Feeding peaks in mid-morning and mid-afternoon, with a rest period in the middle of the day. Weather affects activity, and during cold periods, the Western Black Crested Gibbon decreases travel and rests more. Likewise, fruit availability has been implicated in affecting activity patterns, with periods of high fruit consumption linked to longer travel times to visit this seasonal and sparsely distributed resource. Relative frequencies of behavioral categories have been recorded as 40% resting, 35-1% feeding, 19-9% traveling, 2:6% singing, 1-2% playing, and 1-2% other.
Movements, Home range and Social organization. The social organization of the Western Black Crested Gibbon has long been disputed, with early research suggesting it formed polygynous groups—contested by later researchers. Recent studies on five focal groups in China showed, however, that all occurred in single male-two female groups and that in three of them, both females were breeding; other groups in the area had only a single female. In Vietnam, groups with more than one female are also common. Polygynous groups appearstable in structure, and female antagonism toward other females is rare. This social structure possibly allows groups to more effectively defend their territories, which are large compared with other gibbons. Estimates of home range size vary considerably at 40-151 ha. Large territories may be due to the highly seasonal nature of the forests they occupy. While territories are large, daily movements are similar to other published findings for gibbons. Daily travel distances were variable in one group studied, with a range of 300-3144 m and an average of 1391 m. Monthly distances traveled are correlated with fruit and leaf abundance; daily distances moved are shorter in months with low fruit availability, presumably an energy conservation strategy.
Status and Conservation. CITES Appendix I. Classified as Critically Endangered on The IUCN Red List, along with both subspecies. The Western Black Crested Gibbon is legally protected in China, Vietnam, and Laos. It is known to occur in at least ten protected areas: Wuliangshan, Ailaoshan, Fengshuiling, Huanglianshan, Yongde Daxueshan, and Nanggunhe national nature reserves in China; Mu Cang Chai Species and Habitat Conservation Area and Hoang Lien-Van Ban Nature Reserve in Vietnam; and Nam Ha and Nam Kan biodiversity conservation areas in Laos. China holds the vast majority of the remaining population of the “Tonkin Black Crested Gibbon ” (N. ¢. concolor ). In Yunnan Province its numbers are estimated at 1100-1300 in more than 270 groups. The largest populations are in the parallel chains of the Wuliang and Ailao mountains, with estimates of 87 groups in Wuliangshan National Nature Reserve and more than 150 groups in Ailaoshan National Nature Reserve. In Vietnam, the Tonkin Black Crested Gibbon occurs in two protected areas: Mu Cang Chai Species and Habitat Conservation Area in Yen Bai Province and adjacent forest in Muong La, Son La Province, and Hoang Lien-Van Ban Nature Reserve in Lao Cai Province. The population in Vietnam numbers only 64-70 individuals in 22-25 groups, with ¢.20 groups in Mu Cang Chai/Muong La area and only 2-5 groups in Van Ban. These populations have been monitored since 2001 and have declined despite conservation interventions. Only the population in Mu Cang Chai/Muong La may be viable, but it is severely threatened by hunting and road and dam construction. The “Laotian Black Crested Gibbon ” (N. ¢. lu) is restricted to two protected areas in north-western Laos: Nam Ha and Nam Kan. The population in Nam Ha has been almost extirpated, while that in Nam Kan has only 9-14 groups and receives some protection through an ecotourism project. Hunting and infrastructure development, specifically the building of Road No. 3 through Nam Kan, pose significant threats. Additional undiscovered populations of the Western Black Crested Gibbon may still exist in the north-western and central parts of the northern highlands of Laos.
Bibliography. Bleisch & Chen Nan (1991), Chivers (2001), Dao Van Tien (1983), Duckworth (2008), Fan Pengfei & Jiang Xuelong (2008, 2009, 2010), Fan Pengfei, Fei Hanlan et al. (2010), Fan Pengfei, Jiang Xuelong et al. (2006), Fan Pengfei, Ni Qingyong et al. (2008, 2009), Geissmann (2007a, 2007b), Geissmann et al. (2000), Groves (2001), Haimoff et al. (1986), Jiang Xuelong et al. (2006), Johnson, A. et al. (2005), Lao PDR, MAF (2011), Luo Zhonghua (2010), Ma Shilai & Wang Yingxiang (1986), Ma Shilai et al. (1988), Mootnick & Fan Pengfei (2011), Ni Qingyong & Jiang Xuelong (2009), Ni Qingyong & Ma Shilai (2006), Rawson et al. (2011), Roos et al. (2007), Smith & Yan Xie (2008), Van Ngoc Thinh, Mootnick, Geissmann et al. (2010), Van Ngoc Thinh, Mootnick, Vu Ngoc Thanh et al. (2010).
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