Raffles' banded langur, Banded leaf monkey
The Raffles' banded langur (Presbytis femoralis ), also known as the banded leaf monkey or banded surili, is a species of primate in the family Cercopithecidae. It is endemic to Singapore and southern Peninsular Malaysia. The species underwent taxonomic revisions in 2019 and 2020, in which two former subspecies were elevated to separate species. As a result, the Raffles' banded langur meets the criteria for being listed as critically endangered by the IUCN. It is mainly threatened by habitat loss.
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 ...
In zoology, a folivore is a herbivore that specializes in eating leaves. Mature leaves contain a high proportion of hard-to-digest cellulose, less ...
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TerrestrialTerrestrial animals are animals that live predominantly or entirely on land (e.g., cats, ants, snails), as compared with aquatic animals, which liv...
Among animals, viviparity is the development of the embryo inside the body of the parent. The term 'viviparity' and its adjective form 'viviparous'...
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...
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Not a migrantAnimals that do not make seasonal movements and stay in their native home ranges all year round are called not migrants or residents.
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starts withThe Raffles' banded langur is 43.2 to 61.0 centimetres (17.0 to 24.0 in) long, excluding the tail, with a tail length of 61.0 to 83.8 centimetres (24.0 to 33.0 in). It weighs 5.9 to 8.2 kilograms (13 to 18 lb). It has dark fur on the back and sides with white-colored fur forming a band on the chest and along the inner thighs.
The Raffles' banded langur is diurnal and arboreal, preferring rainforest with trees of the family Dipterocarpaceae. It comes to the ground less frequently than most other leaf monkeys. It lives in both primary and secondary forest, and also in swamp forests and mangrove forests, and even in rubber plantations. It moves primarily by walking on all fours and by leaping.
According to wildlife researcher Charles Francis, it typically lives in groups of 3 to 6. However, a study in Perawang , Sumatra found an average group size of 11 monkeys in mixed-sex groups. The latter study also found an average ratio of 1 adult male to 4.8 adult females in mixed-sex groups and a ratio of 1.25 adult monkeys for every immature monkey in mixed-sex groups. It also found an average range size for a group of 22 hectares, and an average population density of 42 monkeys per square kilometer. Other studies found somewhat smaller home ranges, of between 9 and 21 hectares.
The Raffles' banded langur appears to have two birth seasons, once between June and July and another between December and January. In this study, at least six infants were born between 2008 and 2010, and the authors found low infant mortality, with several infants surviving at least to seven months old. The study also found that the infant coloration of the Singapore population is indistinguishable from that of the Johor, Malaysia population, with infants having white fur with a black stripe down the back from the head to the tail, crossed by another black stripe across the shoulders and to the forearms. Males leave their natal group before reaching maturity, at about 4 years old.
The call of mature males sounds like "ke-ke-ke." Mammalogist Ronald M. Nowak described the species' alarm call as "a harsh rattle followed by a loud chak-chak-chak-chak."
Raffles' banded langurs have occasionally been observed being groomed by long-tailed macaques.
The Raffles' banded langur has a primarily vegetarian diet. Specialized bacteria in its gut allow it to digest leaves and unripe fruit. The Perawang study found that nearly 60% of the diet consisted of fruits and seeds. Another 30% consisted of leaves, primarily young leaves. A different study found that fruit made up 49% of the diet. Unlike some other monkeys, such as the long-tailed macaque, the banded langur destroys the seeds it eats, and so it is not a significant factor in dispersing seeds.
The IUCN assessed Presbytis femoralis as being critically endangered in 2021. At the time they assessed the (then) subspecies P. f. femoralis as vulnerable. After the taxonomic reassessment, there are only about 300–400 Raffles' banded langurs remaining—about 250 to 300 and possibly fewer in Malaysia and about 60 in Singapore. As a result of the small, fragmented population and continuing risk of further deforestation, the species meets the criteria to be listed as critically endangered by IUCN.
