Time budget of daily activity of silvery lutung (Trachypithecus cristatus) in coastal forest habitat at Gunung Padang, West Sumatra

Primate’s time budgets are the important aspect to investigate their ecological influences in their habitat. This study collected data on daily activities in a group of silvery lutung (Trachypithecus cristatus) in coastal forest habitat at Gunung Padang, West Sumatra, Indonesia from August 2018 – July 2019, using instantaneous scan sampling method with 10-min intervals. This study analyzed the activity of wild silvery lutungs in study site, with emphasis on the age-sex differences and montly changes in their activity budget. This group spent most of time resting in their daily activity (average 47.50% of the total daytime resting), then followed by moving, feeding, grooming and other activities (conflict, nursing, urinating-defecating, playing, etc.). Resting peaked simultaneously in the morning and peaked back in the afternoon while moving and feeding decreased in this period. Their time budgets showed significant monthly variation: they spent a higher value of time feeding from September - Oktober 2018. They also differed among different sex-age classes: nursing females spent more time for actively moving, whereas adult male and single females devoted more time to resting, feeding, and grooming. These differences in their time budgets may reflect fundamental differences in reproductive biology, parental investment and development among the different age-sex classes.

Apparent diet digestibility of captive colobines in relation to stomach types with special reference to fibre digestion

Colobine monkeys are known for the anatomical complexity of their stomachs, making them distinct within the primate order. Amongst foregut fermenters, they appear peculiar because of the occurrence of two different stomach types, having either three (‘tripartite’) or four (‘quadripartite’, adding the praesaccus) chambers. The functional differences between tri and quadripartite stomachs largely remain to be explained. In this study, we aim to compare the apparent digestibility (aD) in tripartite and quadripartite colobines. Hence, we measured the aD in two colobine species, Nasalis larvatus (quadripartite) and Trachypithecus cristatus (tripartite), in two zoos. We also included existing colobine literature data on the aD and analysed whether the aD of fibre components is different between the stomach types to test the hypothesis of whether quadripartite colobines show higher aD of fibre components than tripartite colobines did. Our captive N. larvatus specimen had a more distinctively varying nutrient intake across seasons with a larger seasonal variation in aD than that of a pair of T. cristatus, which mostly consumed commercial foods with a lower proportion of browse and less seasonal variation. We observed higher aD of dry matter (DM), neutral detergent fibre (NDF) and acid detergent fibre (ADF) in the N. larvatus specimen, suggesting a higher gut capacity of N. larvatus provided by the additional praesaccus forestomach chamber. Based on the analysis of literature data for aD, we also found that quadripartite species achieved higher fibre digestibility at similar dietary fibre levels compared with tripartite species, supporting the hypothesis that the additional gut capacity offered by the praesaccus facilitates a longer retention and hence more thorough microbial fermentation of plant fibre.

Apparent digestibility of captive colobines in relation to stomach types with special reference to fibre digestion

Colobine monkeys are known for the anatomical complexity of their stomachs, making them distinct within the primate order. Amongst foregut fermenters, they appear peculiar because of the occurrence of two different stomach types, having either three (‘tripartite’) or four (‘quadripartite’, adding the praesaccus) chambers. The functional differences between tri and quadripartite stomachs largely remain to be explained. In this study, we aim to compare the apparent digestibility (aD) in tripartite and quadripartite colobines. Hence, we measured the aD in two colobine species, Nasalis larvatus (quadripartite) and Trachypithecus cristatus (tripartite), in two zoos. We also included existing colobine literature data on the aD and analysed whether the aD of fibre components is different between the stomach types to test the hypothesis of whether quadripartite colobines show higher aD of fibre components than tripartite colobines did. Our captive N. larvatus specimen had a more distinctively varying nutrient intake across seasons with a larger seasonal variation in aD than that of a pair of T. cristatus, which mostly consumed commercial foods with a lower proportion of browse and less seasonal variation. We observed higher aD of dry matter (DM), neutral detergent fibre (NDF) and acid detergent fibre (ADF) in the N. larvatus specimen, suggesting a higher gut capacity of N. larvatus provided by the additional praesaccus forestomach chamber. Based on the analysis of literature data for aD, we also found that quadripartite species achieved higher fibre digestibility at similar dietary fibre levels compared with tripartite species, supporting the hypothesis that the additional gut capacity offered by the praesaccus facilitates a longer retention and hence more thorough microbial fermentation of plant fibre.

Population dynamics and ranging behaviors of provisioned silvered langur (Trachypithecus cristatus) in Peninsular Malaysia

Tourists are attracted to the Bukit Melawati Kuala Selangor (BMKS) of Peninsular Malaysia, a small hill park, both for its status as a historical site and the free-ranging silvered langurs (Trachypithecus cristatus) that come for provisioning. We assessed the population trends and group sizes ofT. cristatusover 10 years in the BMKS and examined their ranging patterns. Comparisons of observed populations between 2005 (190 individuals) and 2017 (193 individuals) revealed the stable demography and group sizes of the sixT. cristatusgroups in the BMKS. Based on a total of 185 location points of the six groups in 2017, their mean ranging area was 3.6 ha with a range of 0.86 to 6.93 ha with extensive spatial overlap. We also found a significant positive correlation between the six groups’ ranges and group sizes in 2017. Additionally, qualitative ecological comparisons with a previous study onT. cristatusin 1965 (before provisioning) suggest that the artificial food supply in the study area could modify the socioecology of theT. cristatus. The modifications might alter their range size and territoriality in the BMKS. Overall, we found that provisioning had negative effects on the ecology ofT. cristatusin the BMKS. Therefore, modifying management policies, such as banning feeding and implementing educational programs, may contribute to their proper conservation.

COMPARISON BETWEEN Trachypithecus auratus AND Trachypithecus cristatus BRAIN SIZE IN INDONESIA

Taxonomic studies on Trachypithecus species in Indonesia define that this genus separated into two species that are Trachypithecus auratus and Trachypithecus cristatus with Trachypithecus auratus auratus as a subspecies. To determine relative brain size differences between species of the genus Trachypithecus in Indonesia and to examine clinal variation, a study related to brain size and morphological characters that affect the brain size is carried out. This study analyzes the brain volume between both species and examines its relationship with morphometric measurement and variables such as sex, age, and specimen location. Brain volumes were calculated from braincase volumes using 0.5 mm silica gel as mini beads. This study reveals that there are significant differences in relative brain size inter-species, sex, age and interaction among variable. Overall, T. auratus have a bigger brain size than T. cristatus, and the brain size of males are larger than females. The older individual tends to have similar brain size with younger ones. The different relative brain size on age level influenced by GSL size. Allometric body size affects the size of the brain directly. Also, there is a clinal trend in relative brain size. Trachypithecus auratus brain size is increasing from West Java to Lombok island. Further study is needed to understand the influence of external factor such as ecological and social factors on brain size in Trachypithecus.

SEBARAN LUTUNG Trachypithecus cristatus (Raffles, 1821) DI PULAU PAHAWANG, INDONESIA

Human and wildlife conflicts have a negative impact, especially langurs whose habitat in a small island. The study objective was to identify presence and the distribution of langurs in a small island. Data were collected using observation methods, then analyzed using descriptive analysis. The results show that there were 23 langur groups that distributed in 23 locations, with the number of smallest groups consisting of 6 individuals and the number of largest groups consisting of 12 individuals. Langur was found in the morning at 05.38 WIB-10.57 WIB and in the afternoon at 17.08 WIB-18.10 WIB. Most of these animals are found in agroforestry areas and a small part in mangrove forests. The highest activity intensity is found in the morning with the form of eating, locomotion (moving), grooming and resting activities. The existence of langurs in a small island is a good thing and must be preserved because langurs belong to protected animals. One way to conserve these animals is to create alternative conservation-based langur tourism.

Short Communication: Activity budget and diet in silvery lutung Trachypithecus cristatus at Gunung Padang, West Sumatra, Indonesia

Akbar MA, Rizaldi, Novarino W, Perwitasari-Farajallah D, Tsuji Y. 2019. Activity budget and diet in silvery lutung Trachypithecus cristatus at Gunung Padang, West Sumatra, Indonesia. Biodiversitas 20: 719-724. We studied the activity budget and diet of a group of wild silvery lutungs (Trachypithecus cristatus) in Gunung Padang, West Sumatra, Indonesia, with special attention to age-and sex-related differences. We conducted behavioral observations between July and October 2016, and found that resting constituted the greatest proportion of their daily activities (46%), followed by moving (38%), feeding (12%), and grooming (4%). Resting peaked between 11 am and 1 pm, while moving decreased in this period. The juveniles showed higher percentage of moving and lower percentage of feeding than the adults. The adult males showed higher percentage of grooming than the adult females. Finally, the nursing females showed lower percentage of resting and higher percentage of grooming than single females. During the study, we recorded 14 plant species consumed by the lutungs. Their dietary composition was composed of 63% foliage and 37% fruit. Both the foliage and fruits of Ficus variegata, a plant species belonging to the family Moraceae, was the most consumed. Foliage was frequently consumed by the nursing females and juveniles. The adult males were frequently observed to eat fruit during the study period. No fruit was consumed by the nursing females.