Primate of the Week: Dusky leaf monkey

Trachypithecus obscurus



  • Suborder: Haplorrhini
  • Infraorder: Simiiformes
  • Superfamily: Cercopithecoidea
  • Family: Cercopithecidae
  • Subfamily: Colobinae


Dusky leaf monkeys are found in the Malay Peninsula, southern Burma, Thailand and several islands within Malaysia (Lekagul and McNeely, 1977; Medway, 1969). They tend to prefer dense forests due to their arboreal lifestyle, however they can be found in several different habitats (Medway, 1969).


Dusky leaf monkeys upper areas ie back, arms and head tend to be a shade of brown grey or black while the under area ie stomach hind legs and their tail are paler. The face is grey and have white fur patches around the eyes and mouth. The palms and soles are hairless and black. Their tail is non prehensile and varies between monkeys. It can be short and hairless to long and hair. Tha tail I also important for balancing when traveling through the canopy. Infant dusky leaf monkeys are bright yellow to orange and will become a greyish color within six months (Grzimenk, 1990; Medway, 1969).


Dusky leaf monkeys are polygynous (Lekagul and McNeely, 1977; Medway, 1969). Mating is intermittent but births generally take place in January, February and March. The gestation is generally 145 days and females have a menstrual cycle of three weeks. Sexually maturity generally occurs between 3 to 4 years (Nowak 1999; Grizmek, 1990; Lekagul and McNeely, 1977).


Dusky leaf monkeys are diurnal. They are generally active in the tree canopy. Their groups are made up of 5 to 20 individuals. Social groups will have one ore more male and two or more adult females. The males are responsible for detecting predators, and patrolling. Dusky leaf monkeys also have a variety of calls including, snorts, hoots, murmurs, and squeaks (Grizmek, 1990; Lekagul and McNeely, 1977).



Grzimek, B. 1990. Grzimek’s Encyclopedia of Mammals; Volume 2. New York: McGraw-Hill Publishing Company.

Lekagul, B., J. McNeely. 1977. Mammals of Thailand. Kurusapha Ladprao.

Medway, L. 1969. The Wild Mammals of Malaya (Peninsular Malaysia) and Singapore. New York: Oxford University Press.

Nowak, R. 1999. Walker’s Mammals of the World, Sixth Edition. Baltimore and London: The Johns Hopkins University Press.

Wisconsin Regional Primate Research Center, University of Wisconsin, Madison, 2000. “Primate Info Net, Dusky Leaf Monkey (Trachypithecus obscurus)” (On-line). Accessed February 12, 2002 at


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