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.
Geographic range and habitat The red-shanked douc is native to Indochina; Vietnam, southern Laos, and possibly northeastern Cambodia, east of the Mekong river. Before 1967, the douc was completely unstudied. It is the only douc species that inhabits all three countries of Indochina. 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 Nghệ An and Gia Lai provinces, from 18°29'N to 14°21'N. The Sơn Trà Nature Reserve on Sơn Trà Mountain 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 one observation of the red-shanked doucs in Cambodia by Rawson and Ross in 2008 in the Ratanakiri Province at the border of Vietnam. 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 1,600 metres (5,200 ft) in elevation. They are arboreal and spend most of their time in the forest canopy, including to sleep. They occasionally get on the ground to drink water or eat dirt that contains minerals. According to an ecological niche model, red-shanked doucs can live between approximately 14°N to 21°N. Their home range is approximately 36 hectares (89 acres) and they have a core area of 8 hectares (20 acres), with a smaller range in the dry season of 24 hectares (59 acres) and a larger range in the wet season of 33 hectares (82 acres). There are weak correlations between precipitation, temperature, and diet and home range but not enough to draw conclusions from them.
Characteristics Like other Doucs, the red-shanked douc is a long, slender monkey. The male has a head and body length of 55–82 centimetres (22–32 in) with a tail that measures 56–74 centimetres (22–29 in), and the female is between 60–63 centimetres (24–25 in) long with a tail that measures 44–60 centimetres (17–24 in) long. Males weigh 8.6–11.4 kilograms (19–25 lb), and females 6.6–10.5 kilograms (15–23 lb). The red-shanked douc are among the most colorful primates. They are considered "Queen of primates" thanks to their distinctive and unique appearance. They have agouti hair on their crown, temples, inner thighs, ventral coat, nape of the neck, back, triceps and lateral sides of their arms. Their crown is silver, their temples are red hair and their foreheads are black. They have white whiskers that are approximately 12 cm long for adult males. Their eyes have a high axis. The fur on their cheeks and on their throat is white. Their collar is orange with black from one shoulder to the other. Their face is a yellow-brown color and they have light blue eyelids. Their inner arms and inner, lateral and back thighs are black while their lower legs are a vibrant red. Their abdomen and back are silver yet their sacral area is white. Both feet and hands are black as well as their nipples. Their tails are white and are oftentimes equal in length to their head and body length. The coloration gradually becomes less vibrant and having smaller red patches with more southern latitudes. In Nam Ghong Provincial Protected Area in Laos, red-shanked doucs only have small red patches around their ankles. Although minor, the red-shanked doucs are sexually dimorphic with respect to body size but not coloration. There is a slight difference in rump markings between males and females; the male has round white spots above the triangle of white on his rump, while the female does not. Males of all ages have a white spot on both sides of the corners of the rump patch, and red and white genitals.
Behavior 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. Grooming lasts up to an hour and is most commonly found between adult females. In captivity, young red-shanked doucs groom and care for infants, showing signs of alloparental care. The activity budget of wild red-shanked doucs is rest at 35.3%, movement at 28.6%, socializing at 21.7%, feeding at 13.7% and self-grooming at 0.7%.
Group composition
… excerpt ends here. Continue reading the full article.
