Bornean Orangutans Pongo Pygmaeus Research Articles

Restoring the orangutan in a Whole- or Half-Earth context

AbstractVarious global-scale proposals exist to reduce the loss of biological diversity. These include the Half-Earth and Whole-Earth visions that respectively seek to set aside half the planet for wildlife conservation or to diversify conservation practices fundamentally and change the economic systems that determine environmental harm. Here we assess these visions in the specific context of Bornean orangutansPongo pygmaeusand their conservation. Using an expert-led process we explored three scenarios over a 10-year time frame: continuation of Current Conditions, a Half-Earth approach and a Whole-Earth approach. In addition, we examined a 100-year population recovery scenario assuming 0% offtake of Bornean orangutans. Current Conditions were predicted to result in a population c. 73% of its current size by 2032. Half-Earth was judged comparatively easy to achieve and predicted to result in an orangutan population of c. 87% of its current size by 2032. Whole-Earth was anticipated to lead to greater forest loss and ape killing, resulting in a prediction of c. 44% of the current orangutan population for 2032. Finally, under the recovery scenario, populations could be c. 148% of their current size by 2122. Although we acknowledge uncertainties in all of these predictions, we conclude that the Half-Earth and Whole-Earth visions operate along different timelines, with the implementation of Whole-Earth requiring too much time to benefit orangutans. None of the theorized proposals provided a complete solution, so drawing elements from each will be required. We provide recommendations for equitable outcomes.

Social pressure drives "conversational rules" in great apes.

In the last decade, two hypotheses, one on the evolution of animal vocal communication in general and the other on the origins of human language, have gained ground. The first hypothesis argues that the complexity of communication co-evolved with the complexity of sociality. Species forming larger groups with complex social networks have more elaborate vocal repertoires. The second hypothesis posits that the core of communication is represented not only by what can be expressed by an isolated caller, but also by the way that vocal interactions are structured, language being above all a social act. Primitive forms of conversational rules based on a vocal turn-taking principle are thought to exist in primates. To support and bring together these hypotheses, more comparative studies of socially diverse species at different levels of the primate phylogeny are needed. However, the majority of available studies focus on monkeys, primates that are distant from the human lineage. Great apes represent excellent candidates for such comparative studies because of their phylogenetic proximity to humans and their varied social lives. We propose that studying vocal turn-taking in apes could address several major gaps regarding the social relevance of vocal turn-taking and the evolutionary trajectory of this behaviour among anthropoids. Indeed, how the social structure of a species may influence the vocal interaction patterns observed among group members remains an open question. We gathered data from the literature as well as original unpublished data (where absent in the literature) on four great ape species: chimpanzees Pan troglodytes, bonobos Pan paniscus, western lowland gorillas Gorilla gorilla gorilla and Bornean orang-utans Pongo pygmaeus. We found no clear-cut relationship between classical social complexity metrics (e.g. number of group members, interaction rates) and vocal complexity parameters (e.g. repertoire size, call rates). Nevertheless, the nature of the society (i.e. group composition, diversity and valence of social bonds) and the type of vocal interaction patterns (isolated calling, call overlap, turn-taking-based vocal exchanges) do appear to be related. Isolated calling is the main vocal pattern found in the species with the smallest social networks (orang-utan), while the other species show vocal interactions that are structured according to temporal rules. A high proportion of overlapping vocalisations is found in the most competitive species (chimpanzee), while vocal turn-taking predominates in more tolerant bonobos and gorillas. Also, preferentially interacting individuals and call types used to interact are not randomly distributed. Vocal overlap ('chorusing') and vocal exchange ('conversing') appear as possible social strategies used to advertise/strengthen social bonds. Our analyses highlight that: (i) vocal turn-taking is also observed in non-human great apes, revealing universal rules for conversing that may be deeply rooted in the primate lineage; (ii) vocal interaction patterns match the species' social lifestyle; (iii) although limited to four species here, adopting a targeted comparative approach could help to identify the multiple and subtle factors underlying social and vocal complexity. We believe that vocal interaction patterns form the basis of a promising field of investigation that may ultimately improve our understanding of the socially driven evolution of communication.

Habitat use by a primate community in a lowland dipterocarp forest in Danum Valley, Borneo.

Knowledge of niche partitioning with respect to habitat is indispensable to understand the mechanism of coexistence of multiple species. Among primates, however, data are still deficient because repeated survey for a sufficiently long time, covering seasonal changes over a large area, is the only way to clarify habitat segregation within a seasonally fluctuating environment. Southeast Asia is particularly interesting because of the supra-annual, highly unpredictable seasonality in fruiting known as mast fruiting. We conducted repeated route census, habitat monitoring, and group tracking for 25 months in two study sites (ca. 10 km apart) in the largely primary lowland dipterocarp forest of the Danum Valley Conservation Area, eastern Sabah, northern Borneo, Malaysia. The five species of diurnal primates (Bornean orangutan Pongo pygmaeus, Müeller's gibbon Hylobates muelleri, red leaf monkey Presbytis rubicunda, long-tailed macaque Macaca fascicularis, and southern pig-tailed macaque M. nemestrina) did not show horizontal spatial segregation. Red leaf monkeys showed preferences for places with short tree height, but their distribution was not confined to such places. In response to the fruiting peak observed once during the study period, orangutans increased their numbers simultaneously in the two study sites. The average tree height used by the five species was different, but their range overlapped substantially. Compared with other primate communities, the lack of horizontal spatial segregation and the suggested long-distance movement of orangutans seem to be unique characteristics in Borneo, although the use of different forest strata is a widespread phenomenon among primate communities throughout the world.

Conserving orangutans one classroom at a time: evaluating the effectiveness of a wildlife education program for school‐aged children in Indonesia

AbstractEnvironmental education is a cornerstone of many wildlife conservation programs, and measuring the impact of such education initiatives is imperative for evaluating their effectiveness in achieving conservation goals. For over 15 years, the Gunung Palung Orangutan Conservation Program (GPOCP) has been working to protect wild Bornean orangutans Pongo pygmaeus wurmbii living in and around Gunung Palung National Park in West Kalimantan, Indonesia. In 2015, we carried out a series of six Environmental Education Expeditions to communities in the remote districts surrounding the Park, engaging 1519 elementary (n = 770) and junior/senior high school (n = 749) students across 24 schools. Before and after engaging with our environmental education activities students were given surveys to assess their knowledge about and attitudes toward orangutans. We found that our educational activities led to 13.6–40.4% increases in student knowledge about orangutans and substantial shifts toward more positive attitudes about conservation, but that many students do not believe that they personally can make a difference. Empowerment may be a key need to link wildlife education to environmental action.

Global population records and managed‐programme updates for the great apes: short report

Keeping records of individual wild animals managed by zoos and aquariums is an essential component of population management, not only on the institutional scale but also to ensure long‐term health and viability of species populations regionally and globally. There are long‐established studbooks for Bornean orangutan Pongo pygmaeus, Sumatran orangutan Pongo abelii, Bonobo Pan paniscus, Chimpanzee Pan troglodytes sspp and Western lowland gorilla Gorilla gorilla gorilla. National and regional zoo and aquarium associations manage these population records through a variety of conservation programmes, ensuring the data are available for those working to conserve great apes and their habitats. This report presents updates for the great ape managed conservation programmes, with specific data provided for the 2016 global zoo populations.

A retrospective review of great ape cardiovascular disease epidemiology and pathology

Cardiovascular disease is associated with significant mortality in zoo‐housed great apes, yet little is known about its epidemiology and aetiopathogenesis, and therefore its diagnosis, treatment and prevention. In this retrospective study, the frequency and patterns of cardiovascular disease‐associated mortality in zoo‐housed great apes is explored. Data relating to 71 great apes [Bonobos Pan paniscus (n = 13), Chimpanzees Pan troglodytes (n = 37), Western lowland gorillas Gorilla gorilla gorilla (n = 15), and Bornean orangutans Pongo pygmaeus and Sumatran orangutans Pongo abelii (n = 6)], which died between 2004 and 2014, were studied and key information relating to their signalment (taxa, age, sex), and manner and cause of death analysed. Male sex and increasing age were found to be associated with an increased risk of cardiovascular disease‐associated death. Relative to the other taxa, orangutans appeared to be less at risk of heart disease‐associated mortality. Deaths were often found to be sudden and unexpected. Cardiomyopathies were the most frequently diagnosed cardiovascular disorder. Of these, a group of cardiomyopathies characterized by the presence of myocardial fibrosis were most common, although there were inconsistencies with regards the reporting of other histopathological features. The study identified potential risk factors involved in great ape cardiovascular disease aetiopathogenesis which warrant further exploration. The findings also suggest a need for proactive screening to identify those affected earlier in the disease course. Finally, the study highlights a critical need for improvements to be made to the current approach to post‐mortem investigation of great ape heart disease and the subsequent reporting of cardiovascular lesions.

Great ape nutrition: low‐sugar and high‐fibre diets can lead to increased natural behaviours, decreased regurgitation and reingestion, and reversal of prediabetes

Great apes in captivity have been affected by a variety of conditions, including obesity, heart, gastrointestinal and dental diseases, and diabetes, all of which are at least influenced by an inappropriate diet. ‘Regurgitation and reingestion’ is also related to diet in great apes. Diets tend to be high in water‐soluble carbohydrates (WSC) (e.g. sugars and starches) and low in fibre. This study aimed to reduce the WSC and increase fibre concentrations of great ape diets, most notably for Chimpanzees Pan troglodytes, Bornean orangutans Pongo pygmaeus, Sumatran orangutans Pongo abelii and hybrid orangutans, and Western lowland gorillas Gorilla gorilla gorilla, and evaluate the behavioural and physiological responses of these species to the dietary changes. Wildlife Reserves Singapore had 4.8 Chimpanzees, 10.5 Bornean orangutans, 5.3 Sumatran orangutans and 2.1 P. pygmaeus × P. abelii orangutan hybrids, and Longleat Safari and Adventure Park, UK, had 4.0 Western lowland gorillas. Behaviour was recorded via scan sampling throughout the diet‐change process with a gradual decline in WSC. Five orangutans and two Chimpanzees were conditioned for finger pricking to monitor their blood‐glucose concentrations. The new diets led to changes in WSC from 59·0–64·3% to 47·5–47·7% and in neutral detergent fibre from 11·5–14·4% to 15·7–22·9% on a dry‐matter basis. These dietary changes significantly increased ‘travelling’, ‘foraging’ and ‘social affiliative’ behaviours, and decreased ‘inactivity’ and ‘abnormal behaviour patterns’, such as ‘regurgitation and reingestion’. Fasting blood glucose also decreased and, eventually, all great apes sampled had average blood‐glucose levels. Orangutans had a stronger insulin response compared with Chimpanzees, which may reflect their feeding ecology.

Opportunistic behaviour or desperate measure? Logging impacts may only partially explain terrestriality in the Bornean orang-utan Pongo pygmaeus morio

AbstractThere is a lack of information on how the Endangered Bornean orang-utan Pongo pygmaeus morio moves through its environment. Here we report on a camera-trapping study carried out over 2.5 years to investigate the orang-utan's terrestrial behaviour in Wehea Forest, East Kalimantan, Indonesia. We set 41 camera trap stations in an area of secondary forest, 36 in recently logged forest immediately adjacent to Wehea Forest, and 20 in an area of primary forest in the heart of Wehea Forest. A combined sampling effort of 28,485 trap nights yielded 296 independent captures of orang-utans. Of the three study sites, orang-utans were most terrestrial in recently logged forest, which may be only partially explained by breaks in the canopy as a result of logging activity. However, orang-utans were also terrestrial in primary forest, where there was a closed canopy and ample opportunity for moving through the trees. Our results indicate that orang-utans may be more terrestrial than previously thought and demonstrate opportunistic behaviour when moving through their environment, including using newly constructed logging roads for locomotion, possibly indicating some degree of resilience to human disturbance. This finding is important because of the potential role of sustainably logged forests for orang-utan conservation.

Population status of the Bornean orang-utan Pongo pygmaeus in a vanishing forest in Indonesia: the former Mega Rice Project

AbstractAs peat-swamp forests in Borneo become progressively more fragmented, the species that inhabit them are increasingly threatened, notably the Endangered Bornean orang-utan Pongo pygmaeus. The area of a failed agricultural project known as the Mega Rice Project in Central Kalimantan, Indonesia, is composed of fragments of peat-swamp forest that are reported to contain orang-utans, although no comprehensive survey has previously been conducted. In a portion of this area we identified remaining forest fragments, using satellite imagery, and surveyed line transects for orang-utan sleeping nests to determine the density, abundance and distribution of the species. The total area of peat-swamp forest in the study area is 76,755 ha, 59,948 ha of which comprises patches at least as large as the home range of a female orang-utan (250 ha). We estimate a mean population density of 2.48 ± SE 0.32 individuals km−2 and a population of 1,700 ± SE 220 or 1,507 ± SE 195 individuals, based on a 25 and 250 ha minimum patch size threshold, respectively. This is c. 40–45% of the original population, and the fragmented population is unlikely to be viable in terms of long-term demographic and genetic stability. To ensure persistence of this population of orang-utans, direct conservation action to connect forest fragments and prevent further loss of peat-swamp forest will be required, including re-establishing the hydrological regime, reforesting barren areas and fighting fires.

Coming down from the trees: Is terrestrial activity in Bornean orangutans natural or disturbance driven?

The orangutan is the world's largest arboreal mammal, and images of the red ape moving through the tropical forest canopy symbolise its typical arboreal behaviour. Records of terrestrial behaviour are scarce and often associated with habitat disturbance. We conducted a large-scale species-level analysis of ground-based camera-trapping data to evaluate the extent to which Bornean orangutans Pongo pygmaeus come down from the trees to travel terrestrially, and whether they are indeed forced to the ground primarily by anthropogenic forest disturbances. Although the degree of forest disturbance and canopy gap size influenced terrestriality, orangutans were recorded on the ground as frequently in heavily degraded habitats as in primary forests. Furthermore, all age-sex classes were recorded on the ground (flanged males more often). This suggests that terrestrial locomotion is part of the Bornean orangutan's natural behavioural repertoire to a much greater extent than previously thought, and is only modified by habitat disturbance. The capacity of orangutans to come down from the trees may increase their ability to cope with at least smaller-scale forest fragmentation, and to cross moderately open spaces in mosaic landscapes, although the extent of this versatility remains to be investigated.

Nest density as determinants for habitat utilizations of Bornean orangutan (Pongo pygmaeus wurmbii) in degraded forests of Gunung Palung National Park, West Kalimantan

Prasetyo D, Sugardjito J (2011) Nest density as determinants for habitat utilizations of Bornean orangutan (Pongo pygmaeus wurmbii) in degraded forests of Gunung Palung National Park, West Kalimantan. Biodiversitas 12: 164-170. Conversion of forests into nonforests areas particularly for the development of timber industry and oil palm plantation in Ketapang district, West Kalimantan province was drastically increased recently. We have conducted an assessment for the density of Bornean orangutans Pongo pygmaeus wurmbii L. in degraded forests of the boundary of Gunung Palung National Park, West Kalimantan in 2004 and 2005. We used line-transects nest-count to survey 39,6 km length at 13 sites including 7 in side the park and the other 6 situated out side the park which holds a difference status of forest management. The differences of nest density between degraded forests habitat was calculated. The olddegraded forest which has been logged for 5 years or more, were containing more new nests in a cluster compared to the recently as well as currently logged. The highest number of orangutan’s nests could be found in the old degraded forest in side the park, whereas the lowest one was obtained in the currently logged protection forest with the density of 3.70 ind/km2 and 0.06 ind/km2 respectively. We compare these results with the survey undertaken previously in the area when the logging and forest conversion activities have just begun in the region in 2001.

Orangutan population density, forest structure and fruit availability in hand-logged and unlogged peat swamp forests in West Kalimantan, Indonesia

We investigated the population density of Bornean orangutans Pongo pygmaeus pygmaeus and aspects of habitat quality in a selectively hand-logged peat swamp forest in West Kalimantan, Indonesia, and in a comparable unlogged forest nearby. We conducted orangutan nest surveys, measured different parameters of forest structure, recorded monthly changes in fruit availability, and noted the sex and the stage of maturity of orangutans encountered. Nest density, an index of orangutan population density, was 21% lower in the logged area. The forest, logged 2 years previously, had fewer large food trees and a greater number of canopy gaps. We discuss these differences in relation to the lower orangutan nest density in the logged forest. Significantly fewer adult orangutans were observed in the logged study area. We hypothesize that fully adult orangutans, particularly females, are the most severely affected by hand-logging.