Analyses of Vegetation Used by Long-tailed Macaque (Macaca fascicularis Raffles 1821) in Tinjil Island

Tinjil Island is a semi-natural breeding facility for long-tailed macaques (Macaca fascicularis) managed by Primate Research Center, IPB University, located at the southern of Java Island and surrounded by the Indian Ocean. Long-tailed macaques are considered frugivorous even though they are well-known for their flexible diet. This study aims to analyse the vegetation supporting the population of long-tailed macaques. Data were collected from six tracks using square sampling plots with the size of 20 m x 20 m for trees as the main plot, inside the main plot were square subplots consisting of 10 m x 10 m for poles, 5 m x 5 m for saplings, and 2 m x 2 m for seedlings. The Important Value Index (IVI) was calculated for each level of vegetation. Hanjuang (Dracaena elliptica) dominated the seedlings with 29.35%, followed by Kampis (Hernandia peltata) with 18.73%, and Kalapari (Pongamia pinnata) with 13.73%. Hanjuang (Dracaena elliptica) also dominated the saplings with 26.83%, followed by Pancal (Syzygium antisepticum) with 19.19%, and Laban (Vitex pubescens) with 12.30%. The poles were dominated by Ki Cau (Dolichandrone spathacea) as high as 59.28%, while Waru (Thespesia populnea) and Ki Ciat (Ficus septica) dominated at 40.47% and 36.15%, respectively. Kampis (Hernandia peltata) dominated the trees with 39.28%, followed by Ki Ara (Ficus glomerata) with 35.56%, and Ki Langir (Dysoxylum amooroides) with 28.70%. Species found on Tinjil Island are mostly Moraceae (9.84%) and Fabaceae (9.84%), followed by Malvaceae (8.20%), Euphorbiaceae (4.92%), Myrtaceae (4.92%), and Anacardiaceae (4.92%). The vegetation in Tinjil Island supports the livelihood of long-tailed macaques on the island because they have an abundance of food and staple food such as figs to help them fulfil the energy needed to survive and reproduce.

Population Estimate of Long-Tailed Macaques (Macaca fascicularis) on Tinjil Island

Tinjil Island was established as a Natural Habitat Breeding Facility for long-tailed macaques (Macaca fascicularis) in 1997. Between February 1998 and January 2007, 603 (61 males and 542 females) simian retrovirus (SRV) free long-tailed macaques were introduced to the island on the south coast of West Java and function as a primate resource and conservation program. To date, 3256 progenies have been harvested and used as the animal model. Therefore, it is necessary to survey the current population of the long-tailed macaques to evaluate whether the population is still under the island’s carrying capacity. This research aims to identify the population estimate of long-tailed macaques currently occupying the island. The observation was conducted in July 2021 using line transect sampling starting from 07.00 AM and 01.00 PM. Twelve observations were conducted during the study using CD and ES transects. CD (Chuck Darsono) and ES (Emil Salim) are the two longest trails on the island and represent the names of the people who initiated the captive breeding of Tinjil Island. The estimated group density of the long-tailed macaques on Tinjil Island is 13.46 groups/km2, while the estimated population density is 111.04 individuals/km2. The population estimated on the island is 627.38±23.53 individuals. The number indicates that the population is still under carrying capacity