Trachypithecus leucocephalus, Tan, 1957

Russell A. Mittermeier, Anthony B. Rylands & Don E. Wilson, 2013, Cercopithecidae, Handbook of the Mammals of the World – Volume 3 Primates, Barcelona: Lynx Edicions, pp. 550-755 : 749-750

154.

White-headed Langur

Trachypithecus leucocephalus

French: Langur a téte blanche / German: WeilRkopflangur / Spanish: Langur de cabeza blanca

Other common names: \ White-headed Black Langur

Taxonomy. Trachypithecus (Presbytis) leucocephalus Tan, 1957 ,

Fusui County, Guangxi, China .

T: leucocephalus is a member of the francois: species group, also known as the karst or limestone langurs. Monotypic.

Distribution. S China, restricted to the counties of Fusui, Chongzuo, Ningming, and Longzhou in SW Guangxi Autonomous Region; it is bordered in the NW and N by the Zuojiang River, in the SW and S by the Mingjiang River, and to the SE by the Shiwan Mts.

Descriptive notes. Head-body 55-62 cm (males) and 47-55 cm (females), tail 82— 89 cm (males) and 77-82 cm (females); weight 8.9-5 kg (males) and 6.7-8 kg (females). Body coloration of the White-headed Langur is dark chocolate-brown. Head is white to ivory-colored, and its hairs form a crest, sometimes with brownish hairs in the tip. White color extends down to shoulders, upper back, and upper chest. White areas on hands, forearms, feet, and lower legs vary individually. Forearms in front are occasionally white, as are feet and lower legs. Tail is brownish at its base and from its tip is white halfto three-quarters of its length. In female White-headed Langurs, white sections on tail, arms, and legs diminish with age. This probably also occurs in males, but there are no long-term observations because of frequent replacement of males in a group. Differences in coloration have led to the assumption of hybridization with Francois’s Langur (7. francoisi ), or that the taxon represents a partial albinistic form of Francois’s Langur. Female White-headed Langurs have a white pubic patch of depigmented skin, with white or yellowish-white hairs. All bare skin on face, ears, hands and feet, is black. White-headed Langurs are born with a bright yellow-orange pelage. Infants change to adult coloration during the first six months oflife.

Habitat. Limestone karst hills, covered with typical limestone forest. Most of the habitat of the White-headed Languris highly fragmented; limestone cliffs, 200-300 m high, are often surrounded by cultivated land with intensive agricultural activities. There are four different vegetation communities on these cliffs that are used differentially by White-headed Langurs. Caves and crevices are used as sleeping sites. The caves offer protection from predators and temperature extremes. Average rainfall in the area is c.1000 mm/year. Average daily temperature is 22-1°C, with a maximum of 39-5°C and a minimum of —-0-5°C.

Food and Feeding. White-headed Langurs are mainly folivorous, with leaves making up 60-92% of their diets; the rest being taken up by shoots, fruits, flowers, and bark. Diets changes during the year, but they always prefer young leaves. There are also differences in species composition of diets among groups and subpopulations. In Fusui Nature Reserve, White-headed Langurs feed on ¢.50 of 164 available plant species, and leaves make up ¢.90% of the diet, of which 60-80% is young leaves and the restis fruits, flowers, buds, and bark. In Bapen Nature Reserve, parts of at least 85 plant species are eaten, and leaves account for 91-4% of the feeding records, of which 79-1% are young leaves. One adult in captivity needed 590-750 g fresh leaves/day. White-headed Langurs also need water for digestion. In captivity, total daily water intake (water from food and drinking water) was 919 ml, or 0-15 ml/g body weight, with 0-12 ml/g from food and 0-03 ml/g from drinking. In the wild, White-headed Langurs lick leaves in the early morning, and drinking at stone hollows is assumed because they are the only places that might contain rainwater. Licking rock faces is a common activity, but it is uncertain if minerals, insects, or lichens are also taken.

Breeding. Male White-headed Langurs reach maturity at c.5 five years, females at 3-5—4 years. In Nonggang Nature Reserve, age offirst copulation for females was c.49 months, and age of first birth was 57-68 months. The gestation period is c.214 days. Births take place throughout the year, but they peak in the first months of the year. In Nonggang, 85-7% of births are in December—March, with a peak in January of 28-6%. Females give birth to a single offspring. Birth interval is 18-28-4 months, and lactation lasts 17-5—20-5 months. One female raises an average of 2-5 offspring during her lifetime. Infant mortality in the first year oflife is 156%. Allomothering behavior mostly occurs during the first month of an infant’s life and gradually decreases from then on. In Fusui Nature Reserve, only groups in high-quality habitat have offspring. As habitat in the Reserve degraded rapidly, groups in low-quality habitat apparently stopped reproducing; this was attributed to the lower diversity and availability of food plants.

Activity patterns. The White-headed Languris diurnal, crepuscular, arboreal, and terrestrial. Daily activity starts with them leaving a sleeping cave at 05:30-06:10 h in summer and 06:45-07:00 h in winter. They enter their caves at 19:45-20:00 h in summer and 17:30-17:45 h in winter. Luminosity is 0-3-0-9 lux when they begin leaving their caves and 2:6-7-5 lux when they enter them at night. A group may use at least three caves, each for a period of 2-4 days. During a year, White-headed Langurs spent an average of 11-5 hours/day outside and 12-5 hours/day inside their caves, accounting for 48% and 52% of their time, respectively. The peak in morning feeding occurs upon leaving caves. There are two feeding peaks per day, one in the morning (c.05:00— 10:00 h) and one in the afternoon (c.16:00-17:00 h). Timing of feeding is considered to be the result of adaption to living in the karst area. On sunny days in summer, temperatures of the surfaces of bare rocks are very high, which results in a higher air temperature over karst areas. During this time, a long rest period at ¢.10:00-16:00 h is common. In winter, White-headed Langurs keep the same regime and use the resting time to sunbathe on bare rocks. Different subpopulations obviously have different time budgets. In Bapen Nature Reserve, ¢.50% of the day is spent resting, 15% each for feeding, traveling, and engaging in social behavior, and ¢.5% playing. In the Longling area, six groups spent an average of 70% resting, 15% feeding, and 10% traveling. In summer, resting time is higher, up to ¢.80%, while feeding time is lower, ¢.10%. In winter, resting time is reduced to ¢.50%, and feeding time increases to 23%. During a study in Hua Shan Nature Reserve in January-May, resting time was 33-6%, feeding time 20-8%, playing 20-2%, moving 13-6%, social behavior 7-3%, vocalization 4-1-%, and sexual activity 0-4%.

Movements, Home range and Social organization. Quadrupedalism is the most frequently form of locomotion of White-headed Langurs on rocks and trees, and they spend ¢.71% of their time when traveling moving on rock surfaces. During walking, running, and leaping, a concave downward arch of the tail is exhibited, as in the northern species of the “limestone langurs,” Francois’s Langur and the Cat Ba Langur (1. poliocephalus ). This posture differs from the southern species, the Hatinh Langur (1. hatinhensis ), the Laos Langur (71. laotum ), and the Black Langur (7. ebenus ). Home ranges of White-headed Langurs are 16-47 ha (average 30-5 ha). Densities are 8 ind/ km? in Fusui Nature Reserve and 17 ind/km? in Longgang. The typical social unit is a polygynous group, with one adult male, several adult females, and their immature offspring. Two adult males in a group are probably brothers or father and son. Females in polygynous groups remain in their natal home range, forming a new group following a group takeover by an invading male. Young males live together and form bachelor groups of up to four individuals. When males become sexually mature, they travel alone and try to take over a group or to split females from a group. Infanticide has been observed in several cases after takeover of a group by an invader. Average group size differs among subpopulations: 5-1 individuals in Fusui Nature Reserve, 9-1 in the Longgang area, 5-3 in Bapen Nature Reserve, and 10-9 in the well-protected Chongzuo Eco Park Nature Reserve. Group size is influenced by habitat quality.

Status and Conservation. CITES Appendix II. Classified as Critically Endangered on The IUCN Red List (as T. poliocephalus leucocephalus ). The White-headed Langur is protected by Chinese law. The total area of its distribution comprises ¢.3500 km? but the fragmented area ofits occurrence is only ¢.200 km®, and subpopulations occur in 16 patches. The largest patch in Ningming and Longzhou is 68 km? while in Chongzou and Fusui County, habitatis highly fragmented with six patches of ¢.43 km* in Chongzuo and nine patches of ¢.88 km? in Fusui. In 2002, the total remaining population of the White-headed Langur was only 580-620 individuals: ¢.250 individuals in Fusui, 90-100 in Chongzuo, and 210-240 in Ningming and Longzhou. Some subpopulations decreased dramatically in the 1980s and 1990s. In Bapen Nature Reserve, the population decreased by ¢.25%. Poaching has been the primary cause of the most recent declines. Clearing land with fire, charcoal production, and burning off agricultural residue are activities that often lead to uncontrolled fires that escape into adjacent karst areas. Tree cutting for firewood has caused further degradation to the remaining habitat. Nevertheless, the population in Nonggang has been growing in the last few years. The population in Guangxi, south of the Zuojiang River,is separated from Francois’s Langur north of the river. Some Francois’s Langurs have been released in the area occupied by the White-headed Langur, resulting in some hybrids. First generation hybrids and their descendants have features more similar to Francois’s Langurs.

Bibliography. Brandon-Jones (1995b), Burton et al. (1995), Groves (2001), Huang Chengming (1998), Huang Chengming & Li Youbang (2002, 2005), Huang Chengming & Lu Liren (1995), Huang Chengming & Sun Ruyong (1997, 2001), Huang Chengming, Lu Liren et al. (1992), Huang Chengming, Sun Ruyong & Lu Liren (1998), Huang Chengming, Sun Ruyong, Xue Yuegui & Li Youbang (2000), Huang Chengming, Wei Fuwen, Li Ming, Li Youbang & Sun Ruyong (2003), Huang Chengming, Wei Fuwen, Li Ming, Quan Guogiang & Li Hanhua (2002), Huang Chengming, Wu Hua et al. (2008), Jiang Haisheng et al. (1991), Lai Yuemai (1987), Li Zhaoyuan (1992, 1993, 2000, 2002), Li Zhaoyuan & Rogers (2004a, 2004b), Li Zhaoyuan et al. (2003), Nadler (2003), Roos et al. (2007), Que Tengcheng et al. (2006), Stevens et al. (2008), Wang Dezhi & Tong Jin (2004).

Figures

149. Tenasserim Langur (Trachypithecus barber), 150. Dusky Langur (Trachypithecus obscurus), 151. Phayre’s Langur (Trachypithecus phayrei), 152. Indochinese Gray Langur (Trachypithecus crepusculus), 153. Cat Ba Langur (Trachypithecus poliocephalus), 154. White-headed Langur (Trachypithecus leucocephalus), 155. Delacour’s Langur (Trachypithecus delacouri), 156. Francois’s Langur (Trachypithecus francoisi), 157. Black Langur (Trachypithecus ebenus), 158. Laos Langur (Trachypithecus laotum), 159. Hatunh Langur (Trachypithecus hatinhensis)

Distribution. S China, restricted to the counties of Fusui, Chongzuo, Ningming, and Longzhou in SW Guangxi Autonomous Region; it is bordered in the NW and N by the Zuojiang River, in the SW and S by the Mingjiang River, and to the SE by the Shiwan Mts.