Francois' leaf monkey, Tonkin leaf monkey, White side-burned black langur, François' langur
The François' langur (Trachypithecus francoisi ), also known as the Francois' leaf monkey, Tonkin leaf monkey, or white side-burned black langur is a species of lutung and the type species of its species group. It is one of the least studied of the species belonging to the Colobinae subfamily.Show More
The species is distributed from Southwestern China to northeastern Vietnam. The total number of wild individuals is unknown, but fewer than 500 are believed to be left in Vietnam and 1,400–1,650 in China. About 60 langurs are in captivity in North American zoos. The species is named after Auguste François (1857–1935), who was the French Consul at Lungchow in southern China.Show Less
Diurnal animals are active during the daytime, with a period of sleeping or other inactivity at night. The timing of activity by an animal depends ...
A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example, foliage, for the main component of its die...
In zoology, a folivore is a herbivore that specializes in eating leaves. Mature leaves contain a high proportion of hard-to-digest cellulose, less ...
Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some anima...
Precocial species are those in which the young are relatively mature and mobile from the moment of birth or hatching. Precocial species are normall...
Browsing is a type of herbivory in which an herbivore (or, more narrowly defined, a folivore) feeds on leaves, soft shoots, or fruits of high-growi...
Terrestrial animals are animals that live predominantly or entirely on land (e.g., cats, ants, snails), as compared with aquatic animals, which liv...
A territory is a sociographical area that which an animal consistently defends against the conspecific competition (or, occasionally, against anima...
Among animals, viviparity is the development of the embryo inside the body of the parent. The term 'viviparity' and its adjective form 'viviparous'...
Polygyny is a mating system in which one male lives and mates with multiple females but each female only mates with a single male.
A dominance hierarchy (formerly and colloquially called a pecking order) is a type of social hierarchy that arises when members of animal social gr...
NoNot a migrant
Animals that do not make seasonal movements and stay in their native home ranges all year round are called not migrants or residents.
François' langurs are medium-sized primates with black, silky hair. They have very distinct white sideburns that grow down from their ears to the corners of their cheeks. Their tails are long and black in color with a white area on the tip. Males are larger and havier than females and have longer tails.
François' langurs are distributed from Southwestern China to northeastern Vietnam. They live in dry and moist forests. Their preferred habitat are limestone cliffs and caves of tropical and subtropical zones.
François' langurs are diurnal and social creatures that spend most of the day resting and foraging. The average group size ranges from 4 to 27. These monkeys live in a matriarchal society where the females lead the group. Within the society, the females share parenting responsibilities with one another and stay in their natal group forever. Males within the group take no part in the raising of the young, and the young males leave the group before reaching sexual maturity. François' langurs are very agile and when on trees move jumping from one tree to another. When it comes to sleeping sites these animals prefer limestone cliffs. They sleep either on ledges or in caves. By living and sleeping in these limestone caves and cliffs, far from flat land, they greatly avoid predation. In addition, these monkeys produce a loud call to declare their territorial spacing. François' langurs choose the sleeping sites that are close to potential foraging sites. This way they conserve energy and reduce travel costs. When they don't go to forage, individuals usually travel along the same route and return to the same sleeping site.
François' langurs live primarily in one-male groups, in which one male mates with multiple females. This means that these animals have a polygynous mating system. The breeding season takes place year-round with the peak in autumn and winter. Females give birth to a single infant after the gestation period that lasts around 6-7 months. Infants are born fully furred with their eyes open and are fairly active. Young are nursed up to two years before being weaned. By that time the mother and other females in the group nurse, groom and take all the care about the infant. Young François' langurs become reproductively mature after 4-5 years of age.
Of the many factors threatening François' langurs' survival today is hunting that has had one of the largest impacts. In Nonggang Nature Reserve (China), where it is most prevalent, the natives believe that the langur has medicinal values, and have hunted them to make wine out of their bones, which they believe could cure fatigue and rheumatism. Another threat to François' langurs is the destruction of their habitat. These animals live on limestone cliffs, and when farmers look to cultivate their land, they light fires on the lower slopes. Limestone is particularly susceptible to fire; therefore, this practice not only destroys their habitats but also causes major food shortages for these langurs because their diet is primarily foliage.
According to the IUCN Red List, the total population size of the François' langur is unknown. However, there are estimated populations of the species in the following areas: Viet Nam - less than 500 individuals; Nonggang Nature Reserve (China) - 75 individuals; Mayanghe Nature Reserve (China) - around 700 individuals. In 2003 in China the total population size of François' langurs was 1,400-1,650 individuals. Currently, this species is classified as Endangered (EN) on the IUCN Red List and its numbers today are decreasing.