Красный дук: Экология, распространение и угрозы исчезновения.

Species of Old World monkey

The red shanked douc (Pygathrix nemaeus) is an arboreal and diurnal Old World monkey belonging to the Colobinae subfamily. They are endemic to Laos, Vietnam, and Cambodia. They are known for their bright colors and exhibit sexual dimorphism through their body size. The species has been declared critically endangered by the International Union for Conservation of Nature, with the main threats being: hunting, habitat loss and pet trade. They are one of three species in the genus Pygathrix, the other two being the black shanked (P. nigripes) and gray shanked (P. cinerea) doucs. Red shanked doucs live in fission fusion, multilevel societies that have a mean of 18 individuals per band. They are folivorous and consume mainly Acacia pruinescens, Ficus racemosa, Millettia nigrescens, Zanthoxylum avicennae and Castanopsis ceratacantha. Their four chambered stomachs that allow for bacterial fermentation help them with their high fiber diet.

The red shanked douc is native to Indochina; Vietnam, southern Laos, and possibly northeastern Cambodia, east of the Mekong river. In Laos, red shanked doucs occur from the southern Nam Ghong Provincial Protected Area to the central north part of the country. Laos is believed to have the largest population of red shanked doucs, with Nakai Nam Theun National Protected Area in central Laos having the most individuals of approximately 4,420 groups, followed by the Hin Namno National Protected Area. In Vietnam, the species lives between Nghe An and Gia Lai provinces, from 18°29'N to 14°21'N. The Son Tra Nature Reserve in central Vietnam holds the greatest Vietnamese population with approximately 700–1300 individuals. The Phong Nha – Kẻ Bàng National Park is also an important Vietnamese site for the species. There was a report of a red shanked douc specimen that was given to the Staatliches Museum by the Dresden Zoological Garden who had said that it originated in Hainan, China but the zoo records no longer exist so it remains uncertain. Red shanked doucs are found in evergreen, semi evergreen and occasionally limestone forests, up to in elevation. Their home range is approximately and they have a core area of , with a smaller range in the dry season of and a larger range in the wet season of There are weak correlations between precipitation, temperature, and diet and home range but not enough to draw conclusions from them. Males of all ages have a white spot on both sides of the corners of the rump patch, and red and white genitals.

This monkey communicates using facial expressions. It has a specific "play face" with the mouth open, teeth partially bared and chin thrust forward. Sometimes, it closes its eyes and paws blindly towards another douc without regard for the hazards of doing so when up a tree. A fixed stare is a threat display. A grimace with the mouth open and the teeth exposed is a submissive gesture given in response to a stare and is also used to initiate grooming or play. The red shanked douc has a low pitched growl that is given as a threat, and a short, harsh distress squeal. During adult play, they perform an eyelid display where they blink their eyes open and closed to show their light blue eyelids. They are a fairly peaceful species and agonistic behavior has been very rarely reported. In the San Diego Zoo, researchers observed that in the instances where there was agonistic behavior, it only lasted a few seconds and did not result in injury.

Red shanked doucs live in multilevel, fission fusion societies in one male/multi female or multi male/multi female groups with a male to female ratio of 1.0:1.63 and an adult to young ratio of 1.1:1.0. The bands contain a mean of 18 individuals in a mean of 2.7 units per band and a mean of 6.5 individuals per unit. Both males and females have their own hierarchies and males are dominant to females. Both males and females will eventually leave the group they were born into. Red shanked doucs fuse overnight and fission during mornings and early afternoons. When they travel by foot, their tail will usually hang down. Like all other Old World monkeys, its tail is not prehensile. It uses its tail solely for balance, and it uses its arms and legs to move through the forest along established routes. When on the move, the group is led by adult males, with juvenile males bringing up the rear and the females and infants staying safe in the middle. This douc is an aerial specialist, moving high up in the canopy. It is very agile and frequently makes breath taking leaps of up to 6 meters (20 feet), leaping with its arms outstretched over its head, pushing off with its legs and landing on two feet. When the group is untroubled, the red shanked douc will move noisily from branch to branch through the forest, crashing through foliage, swinging under branches and leaping with two feet together, displaying its remarkable sense of balance. But when a group is disturbed, by either a predator or other dangers, it can flee silently through the trees, away from danger. If it is startled, it may produce loud barks and rush around the trees slapping branches with its hands and feet.

In captivity, female red shanked doucs reach sexual maturity at four years old and males at four years and eight months. Births occur year round but peak between August and October and again between February and April. The gestation period lasts between 165 and 210 days, resulting in the birth of a single offspring or very rarely, twins. Like all other doucs, they do not have cheek pouches.

In 2000, the IUCN Red List of Threatened Species classified the red shanked douc langur as endangered. In 2020, the IUCN updated their classification of the species to critically endangered, due to the population’s continual decline. It was also listed in the Vietnam Red Book in 2007. In 2019, the Vietnamese prime minister classified them as a high risk species that needs protection, in Decree 06. The species is listed in CITES I, which prohibits commercial international trade. More than half of the species has been lost in the past 30–40 years. The main threat to the red shanked douc is from hunting. Their meat is used for food, traditional medicine, and for international sale or trade. Local people often hunt the species for consumption, pets, or making glue. Although hunting of the species is technically illegal, it is not strictly enforced and has little effect. In the Dong Ampham National Protected Area in Laos, on the border with Vietnam, local hunters have estimated that approximately fifty red shanked doucs are killed each year. From 2015 to 2018, the Bach Ma National Park Forestry Protection department in Vietnam confiscated 13 kg of red shanked douc meat. Their behavioral characteristics are believed to make the species particularly easy to hunt. Vietnam has the highest hunting levels of the species. Their other main threats are pet trade, habitat fragmentation, creation of agricultural land, and military installations. With Laos having the biggest population of red shanked doucs, the country has been marked as being the most important for the species' conservation. A study conducted by Camille N. Z. Coudrat et al. stated that the best approach to conserving the monkeys is to focus on the largest populations, specifically in Laos. At present, there is no conservation effort in that country. There have been efforts to breed red shanked doucs in captivity since the late 1960s, but they are difficult to keep in zoos due to factors such as their diet, so currently, there are only 33 individuals in captivity worldwide. Habitat loss in Son Tra due to development plans poses a high risk to the monkeys. Historically, Son Tra had a military installation, so many animals in the region were shot as practice targets. Currently, the red shanked doucs in Son Tra Nature Reserve are protected by the army, police and forest protection departments of Da Nang and Son Tra.