Post-release adaptation of Javan gibbon (Hylobates moloch) in Mount Malabar Protected Forest, West Java, Indonesia

Post-release adaptation of Javan gibbon (Hylobates moloch) in Mount Malabar Protected Forest, West Java, Indonesia

Abstract. Ario A, Kartono AP, Prasetyo LB, Supriatna J. Twenty eighteen. Post-release adaptation of Javan gibbon (Hylobates moloch) in Mount Malabar Protected Forest, West Java, Indonesia. Biodiversitas nineteen: fourteen eighty-two to fourteen ninety-one. Post-release adaptation study of Javan gibbon (Hylobates moloch) was conducted in twelve months from April twenty sixteen to March twenty seventeen in the Mount Malabar Protected Forest, West Java. We studied eleven Javan gibbons released between March twenty fourteen to August twenty sixteen. The purpose of this study was to assess the adaptive ability of the released Javan gibbons. Data collection was conducted by focal animal sampling method with five-minute interval recording time and ad libitum method. The average time allocation of Javan gibbon activities was the following: feeding twenty-three point zero two plus/minus one point six two percent; moving twenty-six point nine five plus/minus three point zero seven percent; resting forty point eight eight plus/minus three point eight one percent; socializing seven point five six plus/minus three point five five percent; sexual zero point two six plus/minus zero point two four percent; and vocalizing zero point nine five plus/minus zero point two one percent. We compared activity allocation data from this study and those from wild Javan gibbons and found similarities as follows: forty-seven point six zero percent at a family of Jowo-Bombom-Yani-Yudi, sixty-two point four five percent at a pair of Moly-Nancy, fifty-one point seven zero percent at a pair of Robin-Moni and fifty-two point five eight percent at a family of Mel-Pooh-Asri. Post-release adaptation of Javan gibbon is influenced by internal and external factors. Internal factor includes the ability of each individual to develop wild behavior according to its gender and age group, in terms of natural fruit consumption, brachiation movement, morning calls and alarm calls, as well as affiliative bonds among individuals. External factors include the ability of Javan gibbon to adapt to the environment, namely weather conditions and human presence.

INTRODUCTION

The Javan gibbon (Hylobates moloch) is one among nine primate species in the family Hylobatidae in Indonesia. The others were Hylobates agilis, Hylobates albibarbis, Hylobates klossii, Hylobates lar, Hylobates muelleri, Hylobates abbotti, Hylobates funereus, and Symphalangus syndactylus. It is found only on the Island of Java, particularly in conservation forest and protected forest in the western and central part of Java. In addition to habitat loss, hunting for pets is a serious ongoing threat for Javan gibbon.

Fewer than one hundred wild-caught Javan gibbons were in eight rehabilitation centers and eleven zoos on the Islands of Java and Bali. Javan gibbons in rehabilitation centers were usually pets, which were confiscated by the government or given up voluntarily by the previous owners. Rehabilitation and release of Javan gibbon are not easy. Besides being monogamous, highly selective for food and mates, Javan gibbons have a strong sense of territoriality, resulting in a lengthy and costly rehabilitation process. Rehabilitation and reintroduction programs have been widely used as an element of conservation strategies for endangered species. Reintroduction programs provide an opportunity for animals that have lived in captivity to have another chance of living in the wild and may be one way of re-establishing populations that have become locally extinct. The main species to be reintroduced are those that have small and declining population sizes, and limited distribution. Reintroduction should only be undertaken if the program does not threaten wild populations or ecological integrity in reintroduction areas.

To successfully conserve species, preserving wild populations and their habitats is the most crucial factor; yet the wild populations can obtain benefit from rehabilitation and reintroduction programs, while raising public awareness to problems faced by the species. Problems that may emerge during reintroduction programs include mortality before reproduction, disappearance without recovery, no vocalization, no copulation, no development of mating behavior, lack of nutrients, and inability to brachiate. Mortality can be caused by hunting, disease, and starvation.

Post-release monitoring is a crucial step in the rehabilitation process to ensure that wild behavior is developed. Without post-release monitoring, we can not measure objectively and scientifically whether a rehabilitation program is successful.

Javan gibbon's ability to adapt after being released is an indicator of a successful rehabilitation and reintroduction program. This adaptive ability in released Javan gibbon had not been studied previously. Therefore, this research was conducted, aiming to assess the adaptive ability of released Javan gibbons.