Lump gibbon
| Lump gibbon | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Hylobates klossii | ||||||||||||
| ( Miller , 1903) |
The Kloss gibbon ( Hylobates klossii ), also called Mentawai gibbon , Biloh or Zwergsiamang , is a species of primate from the gibbon family (Hylobatidae). Because of their black fur, the Kloss gibbons were previously thought to be close relatives of the Siamangs and were therefore called Zwergsiamangs. Their affiliation to the genus of the small gibbons ( Hylobates ) is undisputed due to morphological similarities and correspondence in the number of chromosomes . The species was named after the zoologist Cecil Boden Kloss (1877-1949), director of the Raffles Museum in Singapore .
features
Kloss gibbons reach a head body length of up to 58 cm and a weight of up to 7 kg. Females are only a little smaller than males, but still have canine teeth that are as long as the males. Both adults and young animals have completely black fur. Because of this characteristic, the animals were given the name Dwarf Siamangs , as they resemble Siamangs , which also have black fur, but are significantly larger. Morphologically, the Kloss gibbon is more similar to the other species of the genus Hylobates . However, the fur is sparse and there is an almost hairless region on the throat. In some ways the skull resembles that of the Siamang.
distribution and habitat
The lump gibbon can only be found on the Mentawai Islands on the west coast of Sumatra . He comes on Siberut , Sipura , North Pagai , South Pagai and Sinakak ago on the east coast Südpagais.
There it inhabits mainly semi-mixed monsoon forests and tropical, evergreen forests at different altitudes. However, some animals have also been observed in swamp forests. The forests on Mentawai are always humid, with annual rainfall of up to 4000 mm. In its area of distribution, the Kloss gibbon is continuously with the short-tailed snub nose ( Simias concolor ), the Siberut langur ( Presbytis siberu ) and the Siberut monkey ( Macaca siberu ) on Siberut and the Mentawai langur ( P. potentiani ) and the Pagai monkeys ( M. pagensis ) sympatric on the southern Mentawai Islands .
Way of life and reproduction
Kloss gibbons are diurnal tree dwellers. One group spends most of the day resting. They do not use sleeping trees for two nights in a row and avoid trees with biting ants . They also choose sleeping places without lianas, as hunters usually climb up lianas. Unlike other types of gibbon, Kloss gibbons do not sing in a duet . Instead, the males perform their chants shortly before dusk and occasionally until after midnight, while females usually sing between 7:00 and 9:00 after the first meal. Although the chants are contagious and after a short time several animals start singing, those of the males in neighboring territories do not overlap. The calls of the females are called "the most beautiful sounds of all land-living mammals" and are often accompanied by choreographic-acrobatic performances. These are individual and each female can be identified by her own reputation. The chants of the males are simpler than those of the females. As with all gibbons, the female chants serve to keep other females out of the territory. Individual, wandering, male Kloss gibbons, who have no territory of their own, were also observed singing, so that it is assumed that the chants have the function of attracting females.
The size of a district is 7 to 32 hectares and varies depending on the quality of the habitat and the quality of the vegetation. On average, the Kloss gibbons migrate 1514 m per day through their territory. A group usually consists of 4 to 6 individuals. Groups of 10 to 15 individuals have been observed on Northern Pagai and Siberut, but it is unclear whether this is the standard here. In general, males behave aggressively towards other males and defend their territory against enemies (humans), while females lead the group and drive away other females. At the age of eight, Kloss-Gibbons set up their own territory and look for a partner. Sometimes parents help young adults to get territories near their own. Occasionally, pups even take the place of a deceased adult of the same sex in parental territory and then live with the remaining adult. In the cases observed, however, it was unclear whether the animals were genetically related. Kloss gibbons are equally common in pristine forests and in forests that were partially cleared ten or twenty years ago. Most of them occur on Siberut. The average abundance in the Mentawai Islands is 12 individuals per km 2 .
Kloss gibbons are mainly frugivorous. Fruits make up about 73% of the diet, but arthropods and other small animals with about 25% and leaves with about 2% (less than other gibbons) are also on the menu. Kloss gibbons behave dominantly towards Siberut and Mentawai langurs and displace them from the food trees when they meet.
Kloss gibbons can reproduce all year round. Single births are the rule. The young animals are still dependent on their mother for up to two years. However, they are not carried by the fathers as is the case with other species. When they are four to six years old, they are considered adolescents. From this point onwards, the young animals show aggressive behavior towards the parent of the same sex. Sexual maturity then occurs at the age of eight. The average life expectancy is more than 30 years.
threat
The lump gibbon is classified by the IUCN as "endangered" (highly endangered). It is protected in Indonesia, but only occurs in one nature reserve, the Siberut National Park. A total of 20,000 to 25,000 individuals still exist in the wild. Most of the Kloss gibbons are found in the Siberut National Park with 13,190 to 15,413 specimens. The total population decline has been around 50% since 1980. The main threats are hunting, commercial deforestation, forest conversion for agriculture, especially for oil palm plantations, and deforestation at the local level. Selective clearing is common in the entire distribution area of the Kloss gibbon, but has only a small impact on the populations. Hunting, on the other hand, has become much more severe in recent years, as the deforestation gives hunters better access to the forests and uses rifles instead of traditional hunting methods. Young Kloss Gibbons are often sold as pets after their parents are shot. They are usually only traded on the Mentawai Islands, but sometimes also on Western Sumatra. Further protected areas are necessary to preserve the species.
literature
- Thomas Geissmann: Comparative Primatology . Springer, Berlin 2003. ISBN 3-540-43645-6
- DE Wilson & DM Reeder: Mammal Species of the World . Johns Hopkins University Press, 2005. ISBN 0-8018-8221-4
- Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson: Handbook of the Mammals of the World. Volume 3: Primates. Lynx Edition, Barcelona 2013, ISBN 978-84-96553-89-7 , p. 781.
Web links
- Information from the Gibbons Research Lab. (English), with photos and sound files
- Hylobates klossii in the Red List of Threatened Species of the IUCN 2006. Posted by: Eudey et al , 2000. Retrieved on 11 May, 2006.
Individual evidence
- ↑ Bo Beolens, Michael Grayson, Michael Watkins: The Eponym Dictionary of Mammals. Johns Hopkins University Press, 2009; P. 225; ISBN 978-0-8018-9304-9 .