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Understanding dietary selection and feeding strategies is important for the conservation and management of endangered primate species. Here, we conducted a preliminary study on the diet and feeding behavior of endangered Shortridge’s langurs (Trachypithecus shortridgei) within the Drung River Valley (Dulongjiang) in southwestern China. The study site lies at a high latitude (N27°47.5′) and elevation (1 900 m a.s.l.) and is characterized by substantial annual rainfall (2 745.1 mm). From August 2012 to September 2013, we observed five groups of langurs and analyzed their overall food composition and dietary variation in spring and autumn. To understand their dietary adaptations to the distinctive habitat of the Drung River Valley, we also compared the diet of Shortridge’s langurs to that of other Trachypithecus species inhabiting different environments. Results indicated that T. shortridgei fed on 52 plant species, 23 of which each accounted for ≥1% of their annual feeding time. Their primary dietary components included leaves (46.2%, young, mature, and petioles), fruits (28.7%, unripe 17.6%, ripe 11.1%), and mosses (10.2%). The langurs mainly consumed mature (34.2%) and young leaves (27.5%) in spring and ripe fruits (39.4%) and mature leaves (24.7%) in autumn. Two species of moss (Macrothamnium macrocarpum and Scapania verrucosa, 21.2% of annual feeding time), which are usually found growing together on cliffs, played a relatively important role in the diet of T. shortridgei. The langurs mainly consumed ripe fruits of Saurauia napaulensis (7.1%) and Dendropanax burmanicus (7.1%), which were abundant at lower elevations. Trachypithecus species in temperate forests consumed more fruits and seeds but fewer leaves (similar mature leaves but fewer young leaves) than those species in tropical forests, which may be related to their availability and abundance. Compared to Trachypithecus species in temperate forests, the higher proportion of mosses and mature leaves but fewer young leaves in the annual diet of T. shortridgei are likely a response to the distinctive Drung River Valley habitat. Therefore, conservation of the main food plants of this threatened species could be vital for its survival and conservation management.

Understanding dietary selection and feeding strategies is important for the conservation and management of endangered primate species. Here, we conducted a preliminary study on the diet and feeding behavior of endangered Shortridge's langurs ( Trachypithecus shortridgei) within the Drung River Valley (Dulongjiang) in southwestern China. The study site lies at a high latitude (N27°47.5') and elevation (1 900 m a.s.l.) and is characterized by substantial annual rainfall (2 745.1 mm). From August 2012 to September 2013, we observed five groups of langurs and analyzed their overall food composition and dietary variation in spring and autumn. To understand their dietary adaptations to the distinctive habitat of the Drung River Valley, we also compared the diet of Shortridge's langurs to that of other Trachypithecus species inhabiting different environments. Results indicated that T. shortridgei fed on 52 plant species, 23 of which each accounted for ≥1% of their annual feeding time. Their primary dietary components included leaves (46.2%, young, mature, and petioles), fruits (28.7%, unripe 17.6%, ripe 11.1%), and mosses (10.2%). The langurs mainly consumed mature (34.2%) and young leaves (27.5%) in spring and ripe fruits (39.4%) and mature leaves (24.7%) in autumn. Two species of moss ( Macrothamnium macrocarpum and Scapania verrucosa, 21.2% of annual feeding time), which are usually found growing together on cliffs, played a relatively important role in the diet of T. shortridgei. The langurs mainly consumed ripe fruits of Saurauia napaulensis (7.1%) and Dendropanax burmanicus (7.1%), which were abundant at lower elevations. Trachypithecus species in temperate forests consumed more fruits and seeds but fewer leaves (similar mature leaves but fewer young leaves) than those species in tropical forests, which may be related to their availability and abundance. Compared to Trachypithecus species in temperate forests, the higher proportion of mosses and mature leaves but fewer young leaves in the annual diet of T. shortridgei are likely a response to the distinctive Drung River Valley habitat. Therefore, conservation of the main food plants of this threatened species could be vital for its survival and conservation management.

The distribution of the capped langur (Trachypithecus pileatus) in China has become controversial since Shortridge's langur (Trachypithecus shortridgei) was upgraded to a full species. The capped langur is considered to be distributed in northeast India, Bangladesh, Bhutan, and northwest Myanmar only (Brandon-Jones et al., 2004; Choudhury, 2008, 2014; Das et al., 2008; Groves, 2001). In our field survey, however, we obtained photos of the capped langur, demonstrating its existence in China.

We conducted community interviews and field surveys to determine the distribution and population of the Endangered Shortridge's capped langur Trachypithecus shortridgei, and the threats to the species, in the Dulong and Nu River valleys of north-western Yunnan Province, China. We found that c. 19 groups of T. shortridgei reside in the Dulong valley, mostly located in the southern portion of the valley. According to interview and observational records in the Gaoligong Mountains to the west of the Nu River, 12 individuals and no groups were observed. Family groups consist of one adult male, 2–3 adult females and up to five young. We estimate the population of T. shortridgei in China to be c. 250–370 individuals. Threats to the species include habitat loss and poaching. We suggest several measures to conserve T. shortridgei, such as a review of the Gaoligong National Nature Reserve management strategy, and increasing engagement, education, inclusion of local people in forest management, and the consistency of enforcement.

Non-human primates often live in socially stable groups characterized by bonded relationships among individuals. Social organization can be used to evaluate living conditions and expansion potential. Bisexual group size, ratio of males to females and group composition are essential elements determining the type of social organization. Although the first report on Shortridge's capped langurs (Trachypithecus shortridgei) was in the 1970s, until now, the species only inhabits forests of the Dulongjiang valley in northwest Yunnan, China, with c. 250-370 individuals in 19 populations. To understand its social organization, we collected data from five groups of Shortridge's langurs at Silaluo in the Dulongjiang valley during August 2012-October 2013. Family groups consist of one adult male, 2-3 adult females and up to five young. Group size averaged 8 (7-9) individuals. The ratio of adult males to females (M/F) was 1:2.9, infants to adult females was (I/F) 1:2.2; and ratio of adults to immatures was 1:1.2, indicating the potential of a population increasing. Birth season was during March-July and the inter-birth interval was two years.

142. Shortridge’s Langur Trachypithecus shortridgei French: Langur de Shortridge / German: Shortridge-Langur / Spanish: Langur de Birmania Other common names: Shortridge’s Capped Langur Taxonomy. Presbytis shortridgei Wroughton, 1915, Burma, Homalin, upper Chindwin. T. shortridgei forms, together with T. pileatus and T. geei, the pileatus species group. The phylogenetic position of this group remains unresolved, and they might have evolved through hybridization of ancestors (3-4-7-1 million years ago) of today’s genera Trachypithecus and Semnopithecus. In the Chindwin headwaters, there might pe intergradation with 7. pileatus or an undescribed variation of 1. shortridgei. Monotypic. Distribution. NE Myanmar, E of the Chindwin River (Kachin State N to Myitkyina District) and SW China (Dulong River Valley in Gongshan County, NW Yunnan Province). Descriptive notes. Head—body 67-72 cm, tail 95-104 cm; no specific data are available for body weight. Shortridge’s Langur is strikingly uniform in color, being silvery-gray on head and body (including underside, crown, and cheek whiskers), with lighter legs. Tail becomes increasingly dark toward tip. Hands and feet are black. Backward-swept cheek whiskers are shorter than those of Capped Langurs (71. pileatus) and Golden Langurs (71. geet), and they contrast with short, upright crown hair. External scrotum is absent. Habitat. Lowland evergreen and semi-evergreen forest at elevations of 200-2500 m. Shortridge’s Languris rarely encountered at higher elevations. It is sympatric with the Stryker’s Snub-nosed Monkey (Rhinopithecus strykerr). Food and Feeding. There is no information available for this species. Breeding. There is no information available for this species. Activity patterns. There is no information available for this species. Movements, Home range and Social organization. There is no information available for this species. Status and Conservation. CITES Appendix I. Classified as Endangered on The [UCN Red List. Shortridge’s Languris protected in Myanmar and China and occurs in at least three protected areas: Hponkanrazi Wildlife Sanctuary and Hkakaborazi National Park in Myanmar and Gaoligongshan National Nature Reserve in China. Langurs occur also in Hukaung Tiger Reserve, but the species is not known. Population numbers of Shortridge’s Langur are unknown, but they are believed to be declining because of habitat loss and hunting. They are hunted for meat and use in traditional medicine, and they are sometimes exported illegally to China. Habitat loss from agriculture, logging, and firewood extraction and the planned Tazone hydroelectric power dam at the Chindwin River are major threats. The latter will result in direct loss of a large part of the remaining habitat used by Shortridge’s Langur and will harm populations via an increase of hunting by dam construction workers. If Shortridge’s Langur does not occur in Hukaung Tiger Reserve, which provides a large area of suitable lowland habitat, it is seriously threatened because most other protected areas in Myanmar are highland habitats, and suitable habitat below 900 m is heavily degraded and fragmented. There is an urgent need for further survey work to determine current population status, limits of distribution, and habitat preferences of this poorly known species. Bibliography. Htun et al. (2008), Groves (2001), Karanth (2008, 2010), Pocock (1939)., Published as part of Russell A. Mittermeier, Anthony B. Rylands & Don E. Wilson, 2013, Cercopithecidae, pp. 550-755 in Handbook of the Mammals of the World – Volume 3 Primates, Barcelona :Lynx Edicions on page 742, DOI: 10.5281/zenodo.6867065