Delacour black langur

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Delacour black langur
Langur de Delacour.jpg

Delacour black langur ( Trachypithecus delacouri )

Systematics
Superfamily : Tailed Old World Monkey (Cercopithecoidea)
Family : Vervet monkey relatives (Cercopithecidae)
Subfamily : Common monkeys and colobus monkeys (Colobinae)
Sub tribus : Langur (Presbytina)
Genre : Crested langurs ( Trachypithecus )
Type : Delacour black langur
Scientific name
Trachypithecus delacouri
( Osgood , 1911)

The Delacour's langur or Panda Langur ( Trachypithecus delacouri ) is a rare monkey from the kind of lutung . Only about 200 individuals inhabit a small area in northern Vietnam ; This makes the Delacour black langur one of the most threatened primate species.

features

The most striking feature of the Delacour black langur is the white hips and thighs that give the appearance of short pants. This clearly distinguishes them from the other species of the francoisi group . The rest of the fur is glossy black. The head is characterized by the tuft of hair common in crested langurs and pale gray hair on the cheeks, which extends from the corners of the mouth to the clearly protruding ears. Like all members of their genus, these primates are slender and the tail is longer than the body.

The head body length is 57 to 62 centimeters, the tail length 82 to 88 centimeters. The weight varies from 6.2 to 10.5 kilograms. On average, males are slightly larger and heavier than females (7.5 to 10.5 kg for males, 6.2 to 9.2 kg for females).

distribution and habitat

Blue, the range of the Delacour black langur south of Hanoi

The distribution area is limited to the mountainous region south of the Vietnamese capital Hanoi . This includes parts of the Vietnamese provinces of Hà Nam , Thanh Hóa , Hòa Bình , Ninh Bình and Nghệ An . There are seventeen isolated populations within the hill country that cannot get together because of natural or man-made barriers. Significant protected areas in the distribution area are the nature reserve Vân Long and the national park Cúc Phương .

The habitat are wooded karst areas .

Way of life

activity

Delacour black langurs are diurnal and mostly stay on the ground, less often on trees. When they go to sleep, they usually retreat to karst caves.

They live in groups with a wide variety of compositions. One finds groups in which both sexes are represented; next to it groups of females led by a single male; or pure male groups. There are also a number of individually living males who do not join any group. The natural group size is 20 to 30 animals. Today, however, this is only achieved in the specially protected nature reserves. In most areas it has decreased to five to seven animals.

The action area was 36 and 46 hectares in size for two groups observed. The animals in these groups covered between 340 and 1530 m each day.

Males in a group often sit on raised rocks and observe the surroundings. If one group meets another, the males develop aggression, which manifests itself in loud screaming, rearing, car chases and short fights.

There are no observations of enemies. Potential enemies, however, are birds of prey , red dogs , tigers , leopards , clouded leopards , golden cats , bengal cats and large snakes .

nutrition

Delacour black langurs are herbivores that feed primarily on leaves. Young leaves and buds make up 59% of the diet, 20% mature leaves, 9% unripe fruits and 5% flowers; the remaining parts are distributed among seeds, ripe fruits and other green parts of plants.

Like all slender monkeys, they have a multi-chambered stomach for a better breakdown of the difficult to digest plant food.

Reproduction

After a gestation period of 170 to 200 days, the female usually gives birth to a single young. Twin births are also rare. As with all crested langurs, this is initially orange-brown in color. At the age of four months, the coat color is black, the white parts of the coat in old animals are now gray. The strong white only shows up at the age of about three years. Males reach sexual maturity at five years of age, females at four. The lifespan is unknown. Two males in a sanctuary were twenty years old and still alive at the end of 2009, so the lifespan can be more than twenty years in any case.

Systematics and names

The Delacour black langur was first described in 1932 by Wilfred Hudson Osgood , who gave the scientific name Pithecus delacouri . The generic name Pithecus was no longer allowed to be used at this point, as the ICZN had declared it invalid in 1929. Subsequently, the Delacour black langur was mostly assigned to the genus Presbytis , in 1996 the combination Trachypithecus delacouri , which is valid today, was used for the first time .

This monkey was named in honor of the French ornithologist Jean Théodore Delacour .

Within the genus of the crested langur, the Delacour black langur forms the so-called francoisi group with five other species . One assumption is that this group began to split up into today's species at the end of the Pleistocene and that the Delacour black langur developed its white color in adaptation to the light limestone subsoil of its habitat.

threat

The Delacour black langur is one of the most threatened primates. In 2009 there were seventeen separate populations. Four populations live in protected areas and make up 40% of the total population. For the remaining thirteen populations, 60% of the individuals, the chances of survival are considered very slim. The largest population is in the Van Long Nature Reserve with 70 individuals. This is also the only place where the population is actually growing, while it is decreasing everywhere else in the range. The total number of individuals is estimated at 200 to 250.

Poaching, limestone mining (partly with dynamite) and also genetic impoverishment due to the low number of individuals are viewed as threats. In contrast, forest destruction plays a smaller role in the distribution area.

The IUCN classifies the Delacour black langur as critically endangered .

Individual evidence

  1. ↑ a b c Harding 2011, p. 119
  2. ^ Francis 2008, p. 267
  3. ↑ Harding 2011, p. 120
  4. ↑ a b c d e Harding 2011, p. 123
  5. ↑ Harding 2011, p. 125
  6. ↑ a b c Harding 2011, p. 124
  7. ↑ Harding 2011, p. 121
  8. ↑ Harding 2011, p. 122
  9. ↑ International Commission on Zoological Nomenclature: "Opinion 114. Under suspension Simia, Simia satyrus and Pithecus are suppressed" . Smithsonian Miscellaneous Collections 1929, Vol. 73, No. 6, pp. 25-26.
  10. ↑ Harding 2011, p. 118
  11. ↑ VT Ða`o: On the trends of the evolutionary radiation on the Tonkin leafmonkey (Presbytis francoisi, Primates: Cercopithecidae). In: Human Evolution 1989, No. 4, pp. 501-507.
  12. ↑ a b Harding 2011, p. 126
  13. ^ IUCN Species Account , accessed January 19, 2012

literature

Web links