NESTING BEHAVIORAL ADAPTATIONS OF ORANGUTAN (PONGO PYGMAEUS MORIO) IN COAL MINING AREA IN EAST KALIMANTAN

Coal mining changed forest structure and composition, it caused large negative impacts on the orangutan. In order to mitigate those negative effects, it is crucial to understand their nesting behavior adaptation in mining area. We investigated 74 times nested event in coal mining rehabilition area (CMRA) in East Kutai and 123 times in the Kutai National Park (Prevab) from October 2013 to September 2014 and include only night nests. We compared both habitats. Orangutans in CMRA built the nest later than in Prevab and used 15 species of trees as nests sites intensively on Senna siamea and Gmelina arborea. In Prevab, 35 species with the higher frequencies on Eusideroxylon zwageri and Dracontomelon dao. The average diameter of nest trees in CMRA smaller than Prevab. The height of nest trees in CMRA with the highest frequency was in 10.1-15 m, while in Prevab was as in 20.1-25 m. Orangutans in CMRA nested at the height of <15 m, lower than in Prevab was >20 m. Reused nest in CMRA was higher than in Prevab. Orangutans in CMRA more often built nests at the peak and limb, while in Prevab at the limb and peak. Orangutans in CMRA had learned to utilize various species and dimensions of trees as the place to build nests

Behavioral, Ecological, and Evolutionary Aspects of Meat-Eating by Sumatran Orangutans (Pongo abelii)

Meat-eating is an important aspect of human evolution, but how meat became a substantial component of the human diet is still poorly understood. Meat-eating in our closest relatives, the great apes, may provide insight into the emergence of this trait, but most existing data are for chimpanzees. We report 3 rare cases of meat-eating of slow lorises, Nycticebus coucang, by 1 Sumatran orangutan mother–infant dyad in Ketambe, Indonesia, to examine how orangutans find slow lorises and share meat. We combine these 3 cases with 2 previous ones to test the hypothesis that slow loris captures by orangutans are seasonal and dependent on fruit availability. We also provide the first (to our knowledge) quantitative data and high-definition video recordings of meat chewing rates by great apes, which we use to estimate the minimum time necessary for a female Australopithecus africanus to reach its daily energy requirements when feeding partially on raw meat. Captures seemed to be opportunistic but orangutans may have used olfactory cues to detect the prey. The mother often rejected meat sharing requests and only the infant initiated meat sharing. Slow loris captures occurred only during low ripe fruit availability, suggesting that meat may represent a filler fallback food for orangutans. Orangutans ate meat more than twice as slowly as chimpanzees (Pan troglodytes), suggesting that group living may function as a meat intake accelerator in hominoids. Using orangutan data as a model, time spent chewing per day would not require an excessive amount of time for our social ancestors (australopithecines and hominids), as long as meat represented no more than a quarter of their diet

Call Cultures in Orang-Utans?

BACKGROUND: Several studies suggested great ape cultures, arguing that human cumulative culture presumably evolved from such a foundation. These focused on conspicuous behaviours, and showed rich geographic variation, which could not be attributed to known ecological or genetic differences. Although geographic variation within call types (accents) has previously been reported for orang-utans and other primate species, we examine geographic variation in the presence/absence of discrete call types (dialects). Because orang-utans have been shown to have geographic variation that is not completely explicable by genetic or ecological factors we hypothesized that this will be similar in the call domain and predict that discrete call type variation between populations will be found. METHODOLOGY/PRINCIPAL FINDINGS: We examined long-term behavioural data from five orang-utan populations and collected fecal samples for genetic analyses. We show that there is geographic variation in the presence of discrete types of calls. In exactly the same behavioural context (nest building and infant retrieval), individuals in different wild populations customarily emit either qualitatively different calls or calls in some but not in others. By comparing patterns in call-type and genetic similarity, we suggest that the observed variation is not likely to be explained by genetic or ecological differences. CONCLUSION/SIGNIFICANCE: These results are consistent with the potential presence of 'call cultures' and suggest that wild orang-utans possess the ability to invent arbitrary calls, which spread through social learning. These findings differ substantially from those that have been reported for primates before. First, the results reported here are on dialect and not on accent. Second, this study presents cases of production learning whereas most primate studies on vocal learning were cases of contextual learning. We conclude with speculating on how these findings might assist in bridging the gap between vocal communication in non-human primates and human speech

Orangutans: geographic variation in behavioral ecology and conservation

This book describes one of our closest relatives, the orangutan, and the only extant great ape in Asia. It is increasingly clear that orangutan populations show extensive variation in behavioral ecology, morphology, life history, and genes. Indeed, on the strength of the latest genetic and morphological evidence, it has been proposed that orangutans actually constitute two species which diverged more than a million years ago — one on the island of Sumatra the other on Borneo, with the latter comprising three subspecies. This book has two main aims. The first is to carefully compare data from every orangutan research site, examining the differences and similarities between orangutan species, subspecies and populations. The second is to develop a theoretical framework in which these differences and similarities can be explained. To achieve these goals the book synthesizes and compares the data, quantify the similarities or differences, and seeks to explain them

The development and maintenance of sex differences in dietary breadth and complexity in Bornean orangutans

Orangutans show a pronounced sexual dimorphism, with flanged males (i.e., males with fully grown secondary sexual characteristics) reaching twice the size of adult females. Furthermore, adult orangutans show sex-specific dispersal and activity patterns. This study investigates sex differences in adult foraging behavior and sheds light on how these differences develop in immatures. We analyzed 11 years of feeding data on ten adult female, seven flanged male, and 14 immature Bornean orangutans (Pongo pygmaeus wurmbii) at Tuanan in Central Kalimantan, Indonesia. We found that the diets of the adult females were significantly broader and required more processing steps before ingestion than the diets of flanged males. We also found evidence for a similar difference in overall diet repertoire sizes. For the immatures, we found that whereas females reached 100% of their mothers’ diet spectrum size by the age of weaning, males reached only around 80%. From the age of 4 years on (i.e., years before being weaned) females had significantly broader daily diets than males. We found no difference in daily or overall diet processing intensity of immature males and females but found preliminary evidence that immature males included fewer items of their mother’s diet in their own diets that were processing-intensive. Overall, our results suggest that by eating a broader variety and more complex to process food items, female orangutans go to greater lengths to achieve a balanced diet than males do. These behavioral differences are not just apparent in adult foraging behavior but also reflected in immature development from an early age on. Significance Statement In many species, males and females have different nutritional needs and are thus expected to show sex-specific foraging behavior. Sex differences in several aspects of foraging behavior have been found in various species, but it remains largely unclear when and how those develop during ontogeny, which is especially relevant for long-lived altricial species that learn foraging skills over many years. In our study, we analyzed a cross-sectional and longitudinal data set containing more than 750,000 feeding events of adult and immature Bornean orangutans (Pongo pygmaeus wurmbii). We found that adult females had significantly broader and more complex diets than males. We also found that these differences started to develop during infancy, suggesting that immature orangutans prepare for their sex-specific foraging niches long before those become physiologically relevant while they are still in constant association with their mothers and before being frequently exposed to other role models

A description of the orangutan's vocal and sound repertoire, with a focus on geographic variation

This chapter provides an overview of the sounds and vocalizations that Sumatran and Bornean orangutans produce. The current data set indicates that there are at least 32 different orangutan sounds and vocalizations that can be distinguished. Interestingly enough not all of these are produced by all individuals in all populations and several occur only in certain populations, but not in others. These preliminary findings indicate that there might be socially learned variation in orangutan sounds and that the cultural domain includes sounds. Future studies should examine such possibilities in detail.</p

The slow ape: High infant survival and long interbirth intervals in wild orangutans

Orangutans (Pongo spp.) are reported to have extremely slow life histories, including the longest average interbirth intervals of all mammals. Such slow life history can be viable only when unavoidable mortality is kept low. Thus, orangutans' survivorship under natural conditions is expected to be extremely high. Previous estimates of orangutan life history were based on captive individuals living under very different circumstances or on small samples from wild populations. Here, we combine birth data from seven field sites, each with demographic data collection for at least 10 years (range 12–43 years) on wild orangutans to better document their life history. Using strict criteria for data inclusion, we calculated infant survival, interbirth intervals and female age at first reproduction, across species, subspecies and islands. We found an average closed interbirth interval of 7.6 years, as well as consistently very high pre-weaning survival for males and females. Female survival of 94% until age at first birth (at around age 15 years) was higher than reported for any other mammal species under natural conditions. Similarly, annual survival among parous females is very high, but longevity remains to be estimated. Current data suggest no major life history differences between Sumatran and Bornean orangutans. The high offspring survival is remarkable, noting that modern human populations seem to have reached the same level of survival only in the 20th century. The orangutans' slow life history illustrates what can be achieved if a hominoid bauplan is exposed to low unavoidable mortality. Their high survival is likely due to their arboreal and non-gregarious lifestyle, and has allowed them to maintain viable populations, despite living in low-productivity habitats. However, their slow life history also implies that orangutans are highly vulnerable to a catastrophic population crash in the face of drastic habitat change

Orang-utan call spectrograms.

<p>Spectrograms of orang-utan calls: a) ‘nest smacks’; b) ‘raspberries’; c) ‘harmonic uuhs’; d) ‘throat scrapes’. The nest smack and raspberry are produced by orangutans during nest building. The harmonic uuh and throatscrape are produced by mothers towards infants that are separated from them and functions as a ‘come-hither’ call because infants return to the mother after these calls.</p

Cumulative distribution of randomised genetic differentiation values (GDV) among populations.

<p>GDVs were generated as follows: the observed behavioural states were randomly assigned to each of the 5 sites a thousand times, thereby producing site pairs with the same, but also with different behavioural states compared to those that were originally observed for each randomisation. For each randomisation, we then calculated GDV, defined as the difference between the averaged genetic maximum composite likelihood distance among sites pairs with different behavioural states and the averaged genetic maximum composite likelihood distance among site pairs with the same behavioural state. If genetic similarity played a role in the observed pattern, the observed GDVs are expected to be positive. The star indicates the value actually observed in this study.</p