Ujung javan Kulon has five species of primates with the brown, long-tailed, Crab-eating, macaques being the most commonly seen especially on beaches and reefs at low tide. Peucang Island ssupports four separate groups numbering over two hundred individuals.
The macaques’ strongly hierarchical society is based on a marline system – daughters stay with the mother as long as they live while juvenile males usually leave the group to join another group or become solitary. Within the group structure there can be several adult males with one being the dominant but tolerant leader.
Female macaques usually rank just below their mothers and, interestingly, above older sisters so that even babies from highly ranked mothers can control adult males and females. Primarily fruit eaters, the macaques’ diet includes a wide variety of food and their cheek pouches can hold the equivalent of a stomach load of food which allows for hasty food gathering to be eaten later. Each group has its own territory and although they sleep in trees they do not build nests and unlike the park’s other primates they are equally at home on the ground or in trees.
Another primate, only found in Java, is the glossy komodo lizardblackish-brown Javan silvered leaf monkey which has long, slender limbs and tail. They frequent most regions of the park particularly the Gunung Honje Range but unlike the macaques their groups are small and usually contain one adult male, several females and their young. The rarely seen Grizzled leaf monkey in slightly heavier than the Javan silvered leaf monkey and has a grey coat, long tail and head crest. Very small populations of this extremely rare and endangered monkey live in the Gunung Payung and Honje Ranges. Also endangered is the Javan or Moloch gibbon which is unique to West Java and its habitat in Ujung Kulon is the primary forests of the Gunung Honje Range. These tail-less primates have grey fluffy coats and black faces annd make a distinctive hooting call resembling their Indonesian name Owa. Gibbons are monogamous, mate for life and live in small family groups consisting of a male, female and one or more young.
The young adults leave the group to roam the forest searching for a mate and new territory. The parks’ fifth primate is the Slow Loris and being nocturnal, sightings are uncommon. Around 25 to 30 cm. in size, it has an ash-grey coat and large round eyes for night vision. The notable characteristic is its slow, smooth, perfectly co-ordinate movements which allow it to freeze in mid-movement for self protection if disturbed.
