| 京都大学霊長類研究所 ＞ ２００８年度 シンポジウム・研究会 ＞ 東南アジア熱帯林の霊長類の野外研究・要旨 | 最終更新日：2009年2月 3日 |
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Community ecology of primates in Danum Valley
Ecological studies on primate community have been conducted mostly in African and American tropics. Studies in South-Eastern Asian tropics are relatively few, except those which focus on a particular species. However, considering the general flowering and proceeding mast fruiting which is unique to South-Eastern Asian tropics, it is very interesting to reveal the mechanism sympatric primates coexist and partition the resources in a highly seasonal environment. The object of this study is to reveal the mechanism of species coexistence, including resource (habitat and food) partitioning and niche separation among diurnal primate species living sympatrically in Southeastern tropical rain forest. The study was conducted in the primary forest in the Danum Valley Conservation Area, near the Danum Valley Field Centre. Five species of diurnal primates live in this forest, including orangutans (Pongo pygmaeus), Bornean (or Muller's) gibbons (Hylobates muelleri), red leaf monkeys (Presbytis rubicunda), long-tailed macaques (Macaca fascicularis), and pig-tailed macaques (Macaca nemestrina). From September 2006 until December 2008, I conducted fallen fruit census, orangutan nest census, and primate census periodically, using existing trails of 10 km in total length. From December 2006 to December 2008, I conducted behavioural observations of red leaf monkeys and other primates to study their diet, activity, ranging, and inter-species encounter. I focus on the seasonal changes of primate abundance and inter-species difference in the diet and tree height, with special reference to the effect of seasonality in fruiting.
Feeding ecology of orangutans in Danum Valley
Orangutan (Pongo spp.) inhabiting the tropical rain forests in Southeast Asia is the most endangered great ape. Recently, it is reported that there are large genetic difference in orangutans not only between islands (Borneo and Sumatra) but also within islands (Kanthaswamy et. al. 2006). Especially, P. p. morio living in Sabah and East Kalimantan shows salient morphological differences compared with other subspecies and species, probably because of the adaptation to poor nutritional conditions (Taylor 2006). To study how they adapt to poor nutritional conditions, we have conducted research on ecology and behavior of P. p. morio in the primary forest since 2004. In this presentation, we report mainly on the seasonal change in orangutan density and feeding behavior with fruit supply. The study site is located in primary lowland dipterocarp forest around Borneo Rainforest Lodge, a tourist lodge established in 1994 in Danum Valley Conservation Area. The area covers river side of Danum river (tributary river of Segama river). We have followed the focal orangutans from morning nest to night nest to record their behavior and food items. Additionally, we have conducted nest census and fallen fruit census every month during the period from 2005 to 2007 including two mast fruiting events (July-August 2005 and May-September 2007). We could observe wild orangutans for 1785 hours (188 days) in total from July 2004 to December 2007. Though we started our observation from 2004, most observations were made after March 2005. We have identified more than 33 individuals. Population density in the study area showed remarkable seasonal change. The number of nests newly found in each month varied between 4 and 73 (21.4 on average) showing three peaks in September 2005, April 2006 and August 2007. Two of these peaks were roughly correspond with the peaks of fruits supply. The nest number increased up to 73 in the middle-scale mast fruiting in 2005 and up to 33 in the small-scale mast fruiting in 2007. However, the peak of April 2006 could not be explained by the influence of fruits supply because both of fruit supply and the time percentage of fruit feeding was very small. We collected 1466 samples of their food that we identified as their food by direct observations. Their food items contained plants of 54 families, 119 genus including 185 species. They ate fruits of 122 species, leaves of 77 species and barks of 42 species. They also ate flowers, mushrooms, bamboos, honey and termites etc. The mean percentage of feeding time on each food categories to the total feeding time was fruits (61%), leaves (22%), barks (12%), and others (5%). However, the time percentage of fruits feeding showed remarkable seasonal change depending on the fruit supply; it increased up to over 90% during the two masts fruiting, in contrast, it decreased to less than 11% when the fruit supply decreased. During the period with small fruit supply, orangutans mainly fed on leaves and barks, especially those of a liana (Spatholobus sp., FABACEAE). These results suggested that orangutans migrate seeking the place with abundant fruits.
Comparison of Feeding Behaviors between Riverine and Inland Habitats in Proboscis Monkeys
Knowledge about the adaptation of proboscis monkeys (Nasalis larvatus) to forests along rivers is incomplete. Previous studies suggest that this adaptation, especially their behavior, in which they typically return to riverside trees for night sleeping, is advantageous for predation avoidance since predators can approach only from the landward side. However, the effect of food availability on their adaptation has not been studied; food availabilities in riverine habitat may be higher than those in inland habitat. To seek this possibility, we focused on the feeding behaviors in proboscis monkeys and attempted to compare their behaviors in riverine (< 50 m from the river) with inland (> 50 m from the river) habitats in the forest along the Menanggul River, Sabah, Malaysia from May 2005?2006. The subjects consisted of a group of 16 habituated monkeys (1 adult male, 6 adult females, 9 immatures). Using focal animal sampling, we observed the adult monkeys for a total of 3,493 hours (riverine habitat: 1,619 h; inland habitat: 1,874 h). Availability and seasonal changes in plant species consumed by the focal monkeys were also determined by vegetation surveys carried out in 2.15 ha along 200?500 m trails in the study site. The mean daily activity time of the monkeys spent for feeding in the inland habitat was significantly longer than that in the riverine habitat (inland: 1.5 h (SD:±0.9); riverine: 0.9 h (±0.9)), indicating that the inland habitat is suitable for feeding places for proboscis monkeys. However, in some months, the monkeys spent more time for feeding in the riverine habitat than that in the inland habitat, in which the time spent for fruit-eating was longer. Although, in most months, consumption of young leaves predominated in both habitats, monthly fruit availability in the riverine habitat was positively correlated to monthly mean daily time of focal monkeys spent in the riverine habitat. Further, monthly fruit availability in the riverine habitat was negatively correlated to monthly mean daily maximum distance of the focal group from the river. These results demonstrate that proboscis monkeys are apt to spend more time in the riverine habitat as long as the fruits are available. Nonetheless, monthly food availability including fruit availability in the riverine habitat was not always higher than that in the inland habitat, suggesting that food availability is not an essential factor for proboscis monkeys adapting to the forest along the river. Other factors for restricting the monkeys to the forest along the river will also be discussed in the presentation.
Sociological studies of proboscis monkeys in Sukau
Proboscis monkeys (Nasalis larvatus) are endemic to Borneo Island inhabiting mangrove, peat swamp or riverine forests. Proboscis monkeys have a unique multi-level social structure. The basic social unit is a one-male group (OMG), consisting of one adult male, several adult females, and their offspring. Since one-male groups regularly associate with each other at sleeping sites, this monkey has been considered to have a multi-level society, the OMG and the band. To reveal the multi-level society of this monkey, I observed the spacing pattern of used sleeping site by proboscis monkey in riverine forests along the Menanggul River which is a tributary of the Kinabatangan River, Sabah, Malaysia from April 2000 to October 2001. I identified eight one-male groups and one all-male group in this study site. The analysis of spacing pattern of used sleeping-site detected that the one-male groups were frequently associated with each other. The one-male groups inhabited at study site divided into two bands. However there were obviously two bands, the one-male groups were not exclusive each other. Sometimes one-male group which belonged to one band associated with another. The degree of inter-group association fluctuated with season. Male replacement occurred in three one-male groups during study period, and the home ranges of the two new one-male groups were extended. Moreover, one of the new one-male groups showed band shift while the other two did not. The distance of sleeping sites between two consecutive nights of one-male groups seemed smaller than that of the all-male group.
Klias Proboscis Monkey Project: Conservation of the last remaining populations of Proboscis Monkeys, Nasalis larvatus, in the Klias Peninsula in the west coast of Sabah, Malaysia
The Klias Proboscis Monkey Project is aimed at conserving the last remaining proboscis monkey populations located in the Klias Peninsula in the west coast of Sabah, Malaysia. It is a two year project which began in November 2007 and will run until October 2009, managed and run by the Institute for Tropical Biology & Conservation, Universiti Malaysia Sabah. It intends to achieve its aim by studying habitat requirements, ecology and behaviour of the proboscis monkeys by focussing on populations of the animal residing in and around the Padas Damit Forest Reserve within the vicinity of Garama in the central part of the Klias Peninsula. The project also incorporates a training component to build capacity for ecological and behavioural field research techniques relating to proboscis monkey, and environmental awareness education component to raise the level of awareness of the need to conserve wild proboscis monkey populations in Sabah.
Introduction of the KUPRI project to study the diversity of gibbons (title tentative)
Gibbon species living in the tropical rain forests of the Southeast Asia are one of the members of apes, while they interestingly show the remarkable biological significances from the perspectives of the ecology, biogeography sociobiology, behavioral ecology, comparative psychology, and genetics, comparing with the other great apes. The current classification system has proposed the 14 species, and all gibbon species showed the specialized social systems of monogamous. Moreover, another well-known characteristic is their loud morning vocalizations. All gibbon species produce stereotyped patterns of vocalizations. Since 2005, we have continued the field research focused on wild agile gibbons (Hylobates agilis), based on the approaches of both field observations in Sumatra Island and wide-area surveys in Southeast Asia. In the field observation in Sumatra, we have attempted population census, their social relationship within and between groups, and developmental studies, mainly using their characteristic vocal behavior. For the wide-area survey, we have continued to reveal the current status of distributions of wild agile gibbon and white-handed gibbons of their related species, from the perspectives of biogeography. Here we will present some recent topics to be revealed, and also show the future possibilities for gibbon research from the field study.
A Monitoring system of a terrestrial mammalian community as the spatial scale of a Forest Management Unit. -An example in Deramakot & Tangkulap Forest Reserve in Sabah
Large and medium mammals in tropical rainforests do not only include many endanger species, such as elephants and orangutans, but are also recognized as flag-species of the community. However, there is no ideal census system which is simple, economic, and applicable to various, even elusive, species, which can be used at large spatial scale (102-103km 2) common as a forest management unit in tropical regions. Recently, automatic sensor camera systems became applicable in several ecological studies of terrestrial medium-large mammals. Setting up numerous automatic cameras randomly, it is feasible to evaluate species diversity and population abundance of each species in an intended area based on the captured species composition and the frequency during a given period. As such technique allows large-scale census it is possible that it might become a standard method used for sustainable forest management, easily allowing the selection of the most appropriate conservation area. Beyond, it is also possible to monitor the impact of logging activities on forest mammals, explain population abundances in correlation to environmental factors, such as different logging techniques, and derive models to forecast species diversity. Thus, future predictions under various management scenarios can be derived on a large-scale. My research includes two objectives: 1) Calculation of the required effort to estimate species diversity and population abundance in a small area (1-10km2). 2) Estimation of species diversity and population abundance at large spatial scale (102-103km2) and building a forecast model. The study area is located in the Deramakot & Tangkulap Forest Reserve (about 800km2), Sandakan, Sabah, where about 100 automatic sensor cameras are in use since 2007.
Seed dispersal by civets
Seed dispersal by vertebrates is a key process in forest dynamics and vegetation recovery (Corlett 1995). In Southeast Asia, where forest has been rapidly logged and/or fragmented, loss of dispersal agents may be a serious threat to tropical plant diversity (Bond, 1994). To date, most studies on seed dispersal have concentrated on primates, fruit bats and a few families of birds in Southeast Asia. However, many degraded Asian landscapes typically lack many of the best-studied dispersal agents, such as gibbons and hornbills. It is important to study the function of the species which can survive in degraded habitats to predict the effects of loss of dispersal agents on tropical rainforest. In this study, I tried to reveal the importance of the Common palm civet, one of the species most tolerant of human disturbance, in seed dispersal in Tabin Wildlife Reserve. We predict that the civet can play very important role in seed dispersal in disturbed habitats because (1) the civets can disperse seeds in long distance, and (2) they defecate to “open sites” (the site without vegetation). I tried to (1) estimate dispersal distance and (2) identify the microenvironmental traits of the sites to which defecate feces (feces sites) and compare the seed survival and growth rate between feces sites and randomly selected sites. I estimated dispersal distance following Murray (1988). First, I tracked activity of 6 individuals (3 male, 3 female) with radio-telemetry. Second, I estimated gut passage time by observing captive individuals. Based on these data, I calculated dispersal distance by D=Σ(Lt×Pd) where L is the probability of an individual civet being a particular distance from the origin at t min, where t varies in 120-min intervals, where P is the probability of a civet passing a seed at d m, and where d varies in 100-m intervals. For the second purpose, I established two 0.5 ha plots (10 m×500 m) and searched feces in these plots. When I could find feces, I recorded the following microenvironments of the feces sites: (a) the number of leaf, (b) the number of adult trees (> 10 cm in dbh), (c) the number of young trees (>1 cm ) within 2 m, (d) the number of seedlings (>30 cm in height) within 1 m, and d) canopy cover (using hemistichal photos). Then, I recorded the microenvironments at the 50 sites randomly selected in each plot, and compared them between feces sites and random sites. I also planted 10 seeds both at feces sites and random sites, and compared seed survival and growth rate 6 month after. My results suggested that civets can carry seeds relatively in long distance and disperse them to the site quite different from random site (= directed dispersal). The estimated mean dispersal distance was 192 m. The maximum was more than 1 km. The feces sites were different from random sites and significantly have lower canopy cover, fewer leaves, fewer adult trees, young trees, and adult trees. Seed survival planted at feces sites was lower than random sites, but seedling growth was higher than random sites, probably because light intensity was higher at feces sites. These results suggest that civets play very important role in seed dispersal in disturbed habitats and can contribute to vegetation recovery.
Conservation of the mammals in commercial forest reserve: Special reference to natural mineral-licks in Deramakot and Malua
Bornean tropical rain forests ranks with the most biologically diverse place in the world. Sabah state has the highest biodiversity in Borneo. However, protected forests share less than 10% of total forest reserve of the state, while commercial forests share 76% at present. So, most of wildlife inhabits in commercial forests, and it is reported that more than 60% of orangutans inhabit in commercial forests. For conserving wildlife in commercial forests, it is necessary to identify hot spot of biodiversity and to conserve the spot with high priority. We focused on natural mineral-lick (NML) which is among the most important mineral sources for herbivores that have difficulty ingesting a sufficient quantity of some essential minerals, particularly sodium through food. We have studied on NML use of the mammals in Deramakot Forest Reserve since 2003 and in Malua Forest Reserve since 2008. Identification of NML by chemical analysis, species of mammals and its frequency by camera trap in NML have been conducted in both forests. Until present we found that 1) NML is one of the hot spot of biodiversity, 2) orangutan is one of the most frequent users, 3) NML with greater concentrations of minerals in seepage soil water were significantly preferred by sambar deer, bearded pigs, and orangutans than those with lower concentrations of minerals, 4) distribution of orangutans is influenced by that of NML, and 5) particularly sambar deer, NML is one of the most important habitats not only for daily supplement but also for reproductive support. Therefore, we suggested that the forest around NML should be protected in commercial forest reserve as high conservation value forest. From last year, Sabah Forestry Department adopted NML to forest management plan of Deramakot.
AN INTRODUCTION TO THE CENTRE FOR PRIMATE STUDIES BORNEO AT THE INSTITUTE FOR TROPICAL BIOLOGY AND CONSERVATION OF THE UNIVERSITI MALAYSIA SABAH
The Centre for Primate Studies Borneo (CPS BORNEO) was established on June 1st, 2007. With the establishment of the centre, both local and international scientists can now better explore the wonderful world of primates in Sabah and Malaysia in general. CPS BORNEO was set up specifically to be a research and reference centre in the field of primates conservation; to act as a reference point for local primatology; to aid in primates populations management and conservation; to provide well-trained and skilled manpower in the fields of primatology and conservation through long and short-term research projects, training programmes and post-graduate supervisions; and to provide a forum of discussion in the forms of workshops and conferences in order to disseminate research findings and other information pertaining to the management and conservation of non-human primate species of Sabah and Malaysia. Five research clusters have been identified as the main research focus of CPS BORNEO: Primate Genetics; Behavioural ecology and sociobiology; Primate health; Infectious diseases and pathology; and Primate monitoring and management. Despite its recent establishment, researchers at the CPS BORNEO have been involved in many research projects concerning various species of non-human primates. These studies are either basic or applied in nature. Many research projects at CPS BORNEO are carried out in collaboration with scientists from abroad. At present, joint research projects exist between CPS BORNEO and the United Kingdom (Cardiff University), Japan (Hokkaido University; Primate Research Institute of Kyoto University), Switzerland (University of Zurich), Portugal (Lisboa University) and the U.S.A (City University of New York). Although many of the research projects are still on going, the outputs from some of the research efforts can already be found in four different formats: Academic publications in high-ranking international scientific journals, popular articles and pamphlets for the general public; Advisory reports for government and private sector (e.g. management plans); Raw data stored in databases; Primates and other vertebrates DNA bank. The DNA BANK at CPS BORNEO is one of the ambitious projects of CPS BORNEO. Its aim is to provide a collection and reference centre for DNA of all Bornean faunas where DNA materials for phylogenetic studies and other studies can be made available for local and foreign scientists. The CPS BORNEO utilizes research facilities ranging from basic science laboratory to fully functional DNA sequencing (ABI3100) laboratory. Other facilities include basic microscopy to electron microscopes and high end phytochemistry laboratory which are able to cater for all basic and applied research needs. Recently, a field station has been established at Sukau in the Lower Kinabatangan region to facilitate field work in this area where 10 species of non-human primates are found. Currently CPS BORNEO is based at and forming an integral part of the Institute for Tropical Biology and Conservation (ITBC) in Universiti Malaysia Sabah. The CPS BORNEO welcomes the support (expertise and research grants) and formations of collaborations with any local and international institutions to work in the abovementioned fields of study for mutual benefit.
京都大学霊長類研究所 ＞ ２００８年度 シンポジウム・研究会 ＞ 東南アジア熱帯林の霊長類の野外研究・要旨
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