Due to a middle- to long-wavelength-sensitive (M/LWS) cone opsin polymorphism, there is considerable phenotypic variation in the color vision of New World monkeys. Many females have trichromatic vision, whereas some females and all males have dichromatic vision. The selective pressures that maintain this polymorphism are unclear. In the present study we compared the performance of dichromats and trichromats in a discrimination task. We examined tri- and dichromatic individuals of two species: brown capuchin monkeys (Cebus apella) and long-tailed macaques (Macaca fascicularis). We also examined one protanomalous chimpanzee (Pan troglodytes). The subjects' task was to discriminate a circular pattern from other patterns in which textural elements differed in orientation and thickness from the background. After they were trained with stimuli of a single color, the subjects were presented with color-camouflaged stimuli with a green/red mosaic overlaid onto the pattern. The dichromatic monkeys and the protanomalous chimpanzee selected the correct stimulus under camouflaged conditions at rates significantly above chance levels, while the trichromats did not. These findings demonstrate that dichromatic nonhuman primates possess a superior visual ability to discriminate color-camouflaged stimuli, and that such an ability may confer selective advantages with respect to the detection of cryptic foods and/or predators.

The genus Macaca, member of sub-family Cercopithecinae, is the most widely distributed non-human primates in Asian countries. The habitats are strongly influence the dietary variation of the populations. The dietary variation of the macaques reflect ecological plasticity in coping with differences both in availability and abundance of food. The macaques are plastic in taking any kind of food that available in their home range and adjust their behaviour according to its abundance. Here, we present the dietary variation of long-tailed macaques (Macaca fascicularis) in the high altitude rain forest of Telaga Warna, West Java, Indonesia. The proportion of their food from natural sources is greater than those from visitors. The natural food consisted of plants, small animals (insects and earthworm), fungi and water from lake. The plant food comprised of 29 species plus a few mosses. The frequency of eating artificial food was influenced by visitors who come for picnic. In this site, the macaques learned that the visiting of tourists is identical with food.

Tsuji et al. 2 2We observed an inter-species association between wild Javan lutungs (Trachypithecus auratus) and rusa deer (Rusa timorensis). In this association, the former drops plant items that the latter subsequently consumes (glean). We investigated whether the association is beneficial for deer that inhabit tropical regions characterized by drastic seasonal changes. Between 2011 and 2013, we conducted field surveys in the Pangandaran Nature Reserve, Indonesia. We observed 248 gleaning events; the total duration (60.1 h) of these gleaning events corresponded to approximately 4% of the lutung observation time. Deer consumed 39 items dropped by lutungs; these items belonged to 28 plant species and included leaves, fruits, and flowers. Gleaning events occurred more frequently during months when rainfall was low and few herbaceous plants grew in grassland patches. Gleaned foods were significantly heavier than non-gleaned foods. Our findings imply that the lutung-deer association is beneficial to deer, by improving nutritional condition during seasons with low food resources.

Abstract. Priawandiputra W, Tsuji Y, Widayati KA, Suryobroto B. 2020. Dung beetle assemblages in lowland forests of Pangandaran Nature Reserve, West Java, Indonesia. Biodiversitas 21: 497-504. Dung beetles play crucial role in forest ecosystem, but no information on the dung beetle fauna has been reported in lowland forest of Java Island, Indonesia. Pangandaran Nature Reserve (PNR) area, which is recognized as lowland habitat of wildlife, can also support diversity of dung beetles. This study was conducted to examine the dung beetle diversity in lowland forests of PNR. The dung beetles were collected using pitfall traps baited with five species of mammal’s feces and hand collection of beetles found on dung along the road, between 2016 and 2018. During the study, 853 individuals of dung beetles from 17 species were collected. The dominant species were Onthophagus babirussa with 434 individuals (50.8%). The species were not dominant in the mountainous forests of West Java and in lowland forests of Southeast Sulawesi and East Kalimantan. The highest dung beetle abundances were found during the dry season (August): 335 individuals in 2017 and 286 in 2018. However, the diversity index value of dung beetles in this study was lower in the dry season than in the wet season (t-test of diversity index, P<0.05). The dung beetle assemblages in PNR were barely similar to most dung beetle studies of other regions.

Leaf monkeys are known to be leaf eaters, and thus, their potential role as seed dispersers has been neglected. However, they do also feed on fruits. To examine the role of leaf monkeys as endozoochorous seed dispersers, we studied the Javan lutung (Trachypithecus auratus) in Indonesia. We compared multiple aspects of seed dispersal processes (amount and diversity of seeds ingested, dispersal distance, and germination rate) of lutungs with that of the sympatric long‐tailed macaque (Macaca fascicularis). Over the study period, 54 percent of the lutung feces contained intact seeds, which was equivalent to the macaque feces contained seeds (62%). Seeds of at least six plant species were detected in the lutung feces, which was less than those found in the macaque feces (>19 plant species). The main species of seeds defecated by both lutungs and macaques was Ficus spp. (seed size: 0.7 mm). Seed shadow, estimated from travel distance (range: 1–299 m) and gut passage rate (24–96 h), had a unimodal‐distribution with a peak at 51–100 m, and was shorter than that reported in published accounts of macaques and other similar and smaller sized frugivores. Finally, germination rates of Ficus spp. seeds ingested by both lutungs and macaques were lower than that of the control seeds. These results imply that the dispersal effectiveness of lutungs would be lower than that of the sympatric primate frugivores. However, at a population level, lutungs could play a significant role as seed dispersers for the small‐seeded species, and therefore, more research into their frugivorous habits is warranted.