About Trachypithecus delacouri (Osgood, 1932)
Delacour's langur, scientifically named Trachypithecus delacouri, is somewhat larger than its two closest relatives: François' langur and the Laotian langur, but has a similar appearance in most other respects. Adult Delacour's langurs have a head-body length ranging from 57 to 62 cm (22 to 24 in), with a tail measuring 82 to 88 cm (32 to 35 in) long. Males weigh between 7.5 and 10.5 kg (17 and 23 lb), while females are slightly smaller, weighing between 6.2 and 9.2 kg (14 and 20 lb). Their fur is mostly black, with white markings on the face and distinct creamy-white fur covering the rump and outer thighs; females also have a patch of pale fur in the pubic area. Like other closely related lutungs, Delacour's langur has a crest of long, upright hair across the forehead and crown. Unlike other species in the group, this crest is somewhat taller and narrower. Delacour's langur is endemic to northern Vietnam, where it is only found in an approximately 6,000 km² (2,300 sq mi) area covering Hanoi, the capital, and the northern Vietnamese provinces of Ninh Bình, Hà Nam, Hòa Bình, and Thanh Hóa. The largest surviving population of the species is thought to inhabit Van Long Nature Reserve in Ninh Bình, where Delacour's langur lives in open forest up to an elevation of 328 m (1,076 ft) in terrain dominated by limestone karst. For reproduction, female Delacour's langurs give birth to a single young after a gestation period of 170 to 200 days. Newborns are born with orange fur and are precocial, born with open eyes and strong arms. The young's fur begins turning black at around four months old. Young are likely weaned between 19 and 21 months old, when the mother is typically ready to breed again. The species does not develop its full adult coat pattern until around three years of age. Females reach sexual maturity at four years old, while males reach sexual maturity at five years old. The total life expectancy of Delacour's langur is around 20 years.
