Bonneted Langur

Maximum longevity: 25.2 years (captivity) Observations: One specimen lived 25.2 years in captivity (Richard Weigl 2005). Still, not much is known about these animals and maximum longevity could be underestimated.

This highly social primate indulges in much play as an infant, and continues to interact extensively as an adult, through well-developed vocal calls and strongly tactile gestures, including grooming and face-to-face hugging. Groups contain between 2 and 15 individuals, and are most commonly made up of one adult male and several females with their young. This unimale system ensures that a dominant male is able to mate with all the females in his group, and must defend them and their young in return. Solitary males and small bachelor groups are formed as well, usually from younger males who have not yet ousted an older dominant male from his group. Some multi-male, multi-female groups are also found, in which the females control the movement and direction, while the males lag behind and are slower to stop eating when the group moves on (3). When travelling, the capped langur group is relatively quiet and individuals keep close together, unless they encounter a rival group. The home ranges are large and frequently overlap with others, and whilst males do not defend food sources, they will act aggressively to defend their females. Male group leaders are particularly aggressive to solitary males, who may try to capture females in order to start a group of their own. Any females who appear to be defecting risk a bite from their dominant male, who will try to herd them together. Upon encountering another unimale group, the two dominant males may have a visual showdown, running in circles around the crown of a tree whilst breaking branches and making alarm vocalisations (3). The capped langur group wakes with the dawn, but they remain in their sleeping trees until the sun has fully risen. Even then they may simply move to higher branches with little foliage where they can bask in the sunlight before heading off to forage. Their diet of leaves demands that they have a specialised digestive system to break down the tough fibre. Enlarged salivary glands release hormones that prepare the leaves for the sacculated stomach: an upper neutral chamber contains bacteria able to break down the fibre before it passes into the lower acidic chamber to be fully digested. The diet includes the leaves, as well as the fruit, flowers, seeds and bark of 35 species of plant. During the rainy season, fruit is eaten more frequently due to its abundance, whereas shortly before and after the monsoon, in May and October, flowers feature more in the diet as flowering peaks. Capped langurs will drink from depressions in the forks of trees, but rarely descend to the ground, particularly when young. They feed mainly in the early morning and late afternoon, and will find a suitable sleeping tree at dusk, changing tree every night. Each langur sleeps in a tree alone, except for mothers who sleep with their young (3). Most mating takes place in the mornings between September and January, but a smaller peak occurs in April and May. Gestation lasts 200 days and births are concentrated between December and April, with the majority occurring in March (6). The single infant will spend the first two months of its life with either its own mother or with another female in the group, known as an allomother, before straying increasingly to play with the other young monkeys. At one year old infants continue to return to their mother when resting during the day, and to be nursed by her in the evening, although they begin to forage alone at 10 or 11 months (3).

The conservation of the capped langur is not an easy task, with such varied threats facing it. Education of the public to reduce hunting and the demand for the meat and “medicinal” products derived from this species may be the key to its survival, but equally, the rate of habitat loss in many areas of Asia has the potential to be devastating and irreversible if not slowed now. T. p. brahma is not found in any protected areas, T. p. durga is found in several national parks and wildlife sanctuaries in Bangladesh, T. p. pileatus is found in three national parks and one wildlife sanctuary in India, and T. p. tenebricus is found in the Royal Manas National Park in Bhutan as well as two national parks and two wildlife sanctuaries in India (7). The species as a whole is found in at least 22 protected areas (2).

Small differences in colouration distinguish the four subspecies of capped langur, but the species as a whole is recognised by the dark grey to black fur of the back, fading to creamy white or golden yellow on the belly. Exceptions include T. p. durga, in which the belly, whiskers and throat are orange, and females of T. p. tenebricus, in which the belly is pale red. The face is black and the crown dark grey – darkest in T. p. tenebricus, and defined by a grey collar, and lightest in T. p. brahma. The cheeks have a yellow-red hue, and the ears, palms and soles are black. The rump and insides of the thighs are light blue, and this colouration is stronger in males than females. Infants are creamy-white with a soft golden tinge all over. The face, ears, palms and soles are pink; the face being darkest. Juveniles lose the glow of gold as they mature and begin to turn an ashy grey, and their bare skin turns from pink to black (3).

The dense and highly productive hill forests of this region are home to the capped langur, which inhabits ecosystems including tropical dry deciduous, subtropical, broad-leaf and evergreen forests, providing there are many streams. It may also be seen in bamboo forest and teak, gamari, simul and sal plantations (3) (5).

Found in the Indian subcontinent, the four subspecies of capped langur are spread across this area. Trachypithecus pileatus pileatus is found in Myanmar and India; T. p. durga in Bangladesh and in the northern ranges of T. p. pileatus' Indian range; T. p. brahma in the Dafla Hills north of the Brahmaputra River in Assam, India; and T. p. tenebricus in India and Bhutan (1) (3).

The capped langur is classified as Endangered (EN) on the IUCN Red List 2006 (1) and is listed on Appendix I of CITES (4). Subspecies: the blond-bellied langur (T. p. pileatus), orange-bellied langur (T. p. durga), Shortridge's capped langur (T. p. shortridgei) and tenebrous capped langur (T. p. tenebricus) are all classified as Endangered (EN), and the buff-bellied capped langur (T. p. brahma) is classified as Data Deficient (DD) on the IUCN Red List 2006 (1). However, current scientific thought is that Shortridge's capped langur is in fact a distinct species, T. shortridgei (2).

The threats to the capped langur are extensive and can be in large part attributed to the rapid development of its range countries. Perhaps the most serious threat – the one that results in the most quantifiable deaths – is hunting for meat, as well as for traditional “medicine” and for sport. The meat, including that on the tail, is eaten, the skin used for knife sheaths, and the fur for clothing. In common with many primate species in Asia, threats also include habitat loss and fragmentation brought about by clearance for crops and plantations, grazing, human settlements, roads, dams and power lines as well as logging for timber, firewood and charcoal production (7). Capped langurs are caught as pets and for zoos, although they are almost never found in zoos outside of Asia (2) (7). Whilst holding individuals captive can be of high value for breeding programmes, the majority of capped langurs in zoos in Asia are either held singly or in same sex groups with no transfers for breeding (7).

The capped langur (Trachypithecus pileatus) is a species of primate in the family Cercopithecidae. It is native to Bangladesh, Bhutan, India, and Myanmar. Its natural habitat is subtropical or tropical dry forests. It is threatened by habitat loss. They are arboreal and gregarious by nature. A herd of capped langurs consists of 2 to 14 langurs led by a single male. They are herbivorous, eating leaves, twigs, buds and fruits.