Order : PRIMATES
Family : Cercopithecidae
Species : Presbytis thomasi

Weight : Up to approx. 6.7 kg

The strikingly patterned Thomas's Leaf Monkey occurs in primary and secondary forests of Aceh Province, on the Indonesian island of Sumatra. Adventurous troupes, which may number from 10 to 20 individuals, are known to venture close to human habitation.

The normal diet of the species comprises young leaves, though  unripe, non-fleshy fruits or insects are sometimes consumed. The hard seeds of the Rubber Tree Hevea brasiliensis, grown in plantations adjacent to the forest, may also be eaten. The large canines allow the tough husks of forest fruits to be easily torn apart.

The fur is grey on the back and dorsal surface of the limbs. The chest, belly and ventral surface of the limbs are pure white. The elegant tail is long and pale in colour, and the feet and hands are black. On the head the crestal fur is grey bordered with white.  Juveniles are fully white.

Habitat loss is the main threat to the future of Thomas's Leaf Monkey, however large areas of native forest still survive in northern parts of Sumatra where this species occurs.

Fig 1 : Adult with clinging juvenile

Fig 2 : These images were taken at Bukit Lawang, Gunung Leuser National Park, Sumatra.

Photos thanks to Andrea Molyneaux