Female Orangutans Research Articles

Individual Behavior Of Female Sumatran Orangutan (Pongo abelii L.) With Management System In Siantar Zoo

The Sumatran orangutan (Pongo abelii) is an endangered species due to the destruction of its forest habitat and deforestation. Various conservation efforts have been made to prevent the orangutan extinction,such as ex-situ conservation in Siantar Zoo.This study aims to determine the behavior of individual female orangutans at Siantar Zoo with a management system. The observatuons was conducted for 14 days in August with the focal animal sampling method and data recorded using the Instantaneous method.The results showed the overall frequency of individual female orangutan behavior were resting (40%), eating (35%), moving (14%), special (6%), self care (4%) and pooping (1%). The behavior of individual female orangutans is influenced by the number of visitors, namely the resting behavior of the crowded visitor category 39,15%, medium category 41.81% and quiet 39.68%. The eating behavior of the crowded visitor category is 37.80%, the medium category is 33.56% and the quiet category is 34.68%. The moving behavior in the quiet, medium and crowded categories is 14.18%; 12.85%; 11.67%. The specific behavior for the quiet, medium and crowded categories was 6.19%; 5.55%; 5.59%. Self-care behavior in the crowded visitor category is 4.34%, the medium category is 4.60% and the quiet category is 4.01%. The behavior of pooping in the crowded category is 1.45%, in the medium category is 1.62% and in the quiet category is 1.27%.The female orangutan management system at Siantar Zoo is analyzed as having a fairly good and regular system. The cage management has met the minimum requirements and the female orangutan has a good body weight and has never been infected with a serious disease.

Assessing the impact of forest structure disturbances on the arboreal movement and energetics of orangutans—An agent-based modeling approach

Agent-based models have been developed and widely employed to assess the impact of disturbances or conservation management on animal habitat use, population development, and viability. However, the direct impacts of canopy disturbance on the arboreal movement of individual primates have been less studied. Such impacts could shed light on the cascading effects of disturbances on animal health and fitness. Orangutans are an arboreal primate that commonly encounters habitat quality deterioration due to land-use changes and related disturbances such as forest fires. Forest disturbance may, therefore, create a complex stress scenario threatening orangutan populations. Due to forest disturbances, orangutans may adapt to employ more terrestrial, as opposed to arboreal, movements potentially prolonging the search for fruiting and nesting trees. In turn, this may lead to changes in daily activity patterns (i.e., time spent traveling, feeding, and resting) and available energy budget, potentially decreasing the orangutan's fitness. We developed the agent-based simulation model BORNEO (arBOReal aNimal movEment mOdel), which explicitly describes both orangutans' arboreal and terrestrial movement in a forest habitat, depending on distances between trees and canopy structures. Orangutans in the model perform activities with a motivation to balance energy intake and expenditure through locomotion. We tested the model using forest inventory data obtained in Sebangau National Park, Central Kalimantan, Indonesia. This allowed us to construct virtual forests with real characteristics including tree connectivity, thus creating the potential to expand the environmental settings for simulation experiments. In order to parameterize the energy related processes of the orangutans described in the model, we applied a computationally intensive evolutionary algorithm and evaluated the simulation results against observed behavioral patterns of orangutans. Both the simulated variability and proportion of activity budgets including feeding, resting, and traveling time for female and male orangutans confirmed the suitability of the model for its purpose. We used the calibrated model to compare the activity patterns and energy budgets of orangutans in both natural and disturbed forests . The results confirm field observations that orangutans in the disturbed forest are more likely to experience deficit energy balance due to traveling to the detriment of feeding time. Such imbalance is more pronounced in males than in females. The finding of a threshold of forest disturbances that affects a significant change in activity and energy budgets suggests potential threats to the orangutan population. Our study introduces the first agent-based model describing the arboreal movement of primates that can serve as a tool to investigate the direct impact of forest changes and disturbances on the behavior of species such as orangutans. Moreover, it demonstrates the suitability of high-performance computing to optimize the calibration of complex agent-based models describing animal behavior at a fine spatio-temporal scale (1-m and 1-s granularity).

A composite menstrual cycle of captive orangutans, with associated hormonal and behavioral variability.

Knowledge of species-typical reproductive endocrinology profiles is crucial for testing hypotheses pertaining to the evolutionary history, reproductive parameters, and life history of a species, and for managing the well-being of individual animals in human care. Large-scale empirical measurements of ovarian hormones, however, are rare for most primate species, including orangutans. In this study, we used enzyme immunoassays (EIA) to quantify estrogen (estrone conjugates; E1 C) and progesterone (pregnanediol-3-glucuronide; PdG) levels for 98 cycles in 7 cycling zoo-housed female orangutans (10-43 years old). We use a subset of these cycles (N = 44) to create the first composite menstrual cycle for orangutans, which serves as a valuable baseline for future comparative analyses and veterinary considerations. Similar to previous studies, we determined the mean ovarian cycle length of orangutans to be 29.7 days (N = 98 cycles), although we illustrate evidence of both intra- and interindividual variation in ovarian steroid production. Given that this study took place in captivity, we consider how energetic and psychosocial aspects of the zoo environment, such as greater food availability and potential stress, may affect the reproductive physiology and sexual behavior of these females. Furthermore, we discuss the role that age and genetic background may play in producing variability. Finally, we test whether ovarian hormone levels correlate with the reproductive behaviors of these female orangutans using associated behavioral data. Our results suggest that matings are more common during the periovulatory period than outside of it, but do not support a consistent link between hormonal indices of fecundability and mating behaviors in these individuals.

Орангутан Фрина. Первый год в Москве

Introduction. The life of a female orangutan named "Phryne" is described in the article. Phryne lived in the Moscow Zoo in 1927–1936. Large apes can serve as model objects for studying the processes of human growth and development, the formation of mental qualities and social hierarchy, as well as ecological relationships. Therefore, the preservation of accumulated experience is an extremely important task. Materials and methods. Materials from scientific and popular publications, as well as archival materials are used in this work. Analytical and chronological research methods were used. Results. Male and female orangutans were captured on the island of Sumatra in 1926 for the Moscow Zoo. In April 1927, during transportation, the female gave birth to a cub. The apes arrived at the Moscow Zoo on July 14. The female was seriously ill. On July 27 she died. The cub was left without a mother. M.A. Velichkovsky, the head of the monkey section, fed the baby with goat's milk from a pacifier. The baby was first mistaken for a male and named Fritz. After a few years, people realized that it was a female. She was named Phryne. The article talks about Phryne's childhood, about the attitude of the male towards her, about the nutrition of monkeys. It also addresses the fate of the head of the monkey section M.A. Velichkovsky. Conclusion. The first year of Phryne's life was very difficult. The experience of growing an orangutan has become an important stage in the development of the Moscow Zoo.

After the smoke has cleared: Extended low fruit productivity following forest fires decreased gregariousness and social tolerance among wild female Bornean orangutans (Pongo pygmaeus wurmbii)

As climate change continues to fundamentally alter resource landscapes, the ability to flexibly respond to spatio-temporal changes in the distribution of preferred food sources is increasingly important for the overall health and fitness of animals living in seasonal, variable, and/or changing environments. Here, we investigate the effects of an uncharacteristically long period of fruit scarcity, following widespread thick haze caused by peat and forest fires in 2015, on the behaviour and sociality of female Bornean orangutans (Pongo pygmaeus wurmbii). We collected data from 2010 to 2018 at Tuanan, Central Kalimantan, Indonesia, and compared the activity, diet, and association patterns of adult females during low-fruit periods before the fires, i.e., regular, seasonal periods of low fruit availability (“pre-fire”), and after the fires, i.e., during the extended period of low fruit availability (“post-fire”). First, we found that, post-fire, female orangutans adopted a more extreme energy-saving activity pattern and diet — resting more, travelling less, and diet-switching to less-preferred foods — compared to pre-fire. Second, we found that the probabilities of association between females and their weaned immature offspring, and between related and unrelated adult females were lower, and the probability of agonism between unrelated females was higher, post-fire than pre-fire. This change in energetic strategy, and the general reduction in gregariousness and social tolerance, demonstrates how forest fires can have lasting consequences for orangutans. Fission–fusion species such as orangutans can mitigate the effects of changes in resource landscapes by altering their (sub)grouping patterns; however, this may have long-term indirect consequences on their fitness.

I Wanna Draw Like You: Inter- and Intra-Individual Differences in Orang-Utan Drawings.

Simple SummaryDrawing has increasingly been proposed as an enrichment activity for captive primates in zoological parks and research institutes. The monkeys and apes are free to use the materials at their disposal and are not constrained or conditioned to show this behaviour. This provides a good opportunity to collect drawings by non-human primates and allows for comparative studies between hominids. This study is based on 749 drawings recovered from five orang-utans (Pongo pygmaeus) at Tama Zoological Park in Japan, where caretakers regularly facilitated drawing activities for the apes. Analyses showed that individuals differ in their drawing style, especially in the colours used, the space they filled, and the shapes they drew. One individual, Molly, did more complex drawings than other individuals and drew differently according to the seasons and her age. This study is the first to reveal such individual differences and can give some clues about the emergence of drawings in human beings.This study analyses 749 drawings by five female Bornean orang-utans (Pongo pygmaeus) at Tama Zoological Park in Japan. We searched for differences between individuals but also tried to identify possible temporal changes among the drawings of one individual, Molly, who drew almost 1300 drawings from 2006 to 2011. An analysis of the drawings was carried out after collecting quantitative and qualitative variables. Our findings reveal evidence of differences in the drawing style of the five individuals as well as creative changes in Molly’s drawing style throughout her lifetime. Individuals differed in terms of the colours used, the space they filled, and the shapes (fan patterns, circles, or loops) they drew. Molly drew less and less as she grew older, and we found a significant difference between drawings produced in winter, when orang-utans were kept inside and had less activity, and those produced during other seasons. Our results suggest that the drawing behaviour of these five orang-utans is not random and that differences among individuals might reflect differences of styles, states of mind, and motivation to draw.

Immature wild orangutans acquire relevant ecological knowledge through sex-specific attentional biases during social learning.

As a part of growing up, immature orangutans must acquire vast repertoires of skills and knowledge, a process that takes several years of observational social learning and subsequent practice. Adult female and male orangutans show behavioral differences including sex-specific foraging patterns and male-biased dispersal. We investigated how these differing life trajectories affect social interest and emerging ecological knowledge in immatures. We analyzed 15 years of detailed observational data on social learning, associations, and diet repertoires of 50 immatures (16 females and 34 males), from 2 orangutan populations. Specific to the feeding context, we found sex differences in the development of social interest: Throughout the dependency period, immature females direct most of their social attention at their mothers, whereas immature males show an increasing attentional preference for individuals other than their mothers. When attending to non-mother individuals, males show a significant bias toward immigrant individuals and a trend for a bias toward adult males. In contrast, females preferentially attend to neighboring residents. Accordingly, by the end of the dependency period, immature females show a larger dietary overlap with their mothers than do immature males. These results suggest that immature orangutans show attentional biases through which they learn from individuals with the most relevant ecological knowledge. Diversifying their skills and knowledge likely helps males when they move to a new area. In sum, our findings underline the importance of fine-grained social inputs for the acquisition of ecological knowledge and skills in orangutans and likely in other apes as well.

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 StatementIn 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.

The cost of associating with males for Bornean and Sumatran female orangutans: a hidden form of sexual conflict?

Sexual coercion, in the form of forced copulations, is relatively frequently observed in orangutans and generally attributed to their semi-solitary lifestyle. High ecological costs of association for females may be responsible for this lifestyle and may have prevented the evolution of morphological fertility indicators (e.g., sexual swellings), which would attract (male) associates. Therefore, sexual conflict may arise not only about mating per se but also about associations, because males may benefit from associations with females to monitor their reproductive state and attempt to monopolize their sexual activities. Here, we evaluate association patterns and costs for females when associating with both males and females of two different orangutan species at two study sites: Suaq, Sumatra (Pongo abelii), and Tuanan, Borneo (Pongo pygmaeus wurmbii). Female association frequency with both males and females was higher in the Sumatran population, living in more productive habitat. Accordingly, we found that the cost of association, in terms of reduced feeding to moving ratio and increased time being active, is higher in the less sociable Bornean population. Males generally initiated and maintained such costly associations with females, and prolonged associations with males led to increased female fecal cortisol metabolite (FCM) levels at Tuanan, the Bornean population. We conclude that male-maintained associations are an expression of sexual conflict in orangutans, at least at Tuanan. For females, this cost of association may be responsible for the lack of sexual signaling, while needing to confuse paternity.Significance statementSocioecological theory predicts a trade-off between the benefits of sociality and the ecological costs of increased feeding competition. Orangutans’ semi-solitary lifestyle has been attributed to the combination of high association costs and low predation risk. Previous work revealed a positive correlation between association frequencies and habitat productivity, but did not measure the costs of association. In this comparative study, we show that females likely incur costs from involuntary, male-maintained associations, especially when they last for several days and particularly in the population characterized by lower association frequencies. Association maintenance therefore qualifies as another expression of sexual conflict in orangutans, and especially prolonged, male-maintained associations may qualify as an indirect form of sexual coercion.

PEMANFAATAN RUANG VERTIKAL PADA AKTIVITAS HARIAN ORANGUTAN (Pongo pygmaeus wurmbii) DI STASIUN RISET CABANG PANTI TAMAN NASIONAL GUNUNG PALUNG, KALIMANTAN BARAT

Orangutans are solitary animals from the Pongidae family. There are three sub-species of Bornean orangutans, i.e. Pongo pygmaeus wurmbii, P. pygmaeus pygmaeus and P. pygmaeus morio, all of which are highly endangered. Orangutans carry out several daily activities such as eating, moving, resting, and nesting in the tree canopy. However, it has yet remains unknown on how their behaviours vary with tree height. This study aimed to determine the frequency of presence, daily activities of orangutans, and vertical space utilization in orangutan activities in the natural habitat of the Panti Branch Research Station, Gunung Palung National Park. This study used the Focal Animal Sampling method with a two minute time interval for ± 12 hours and was studied for over six months. The focal orangutans whose activities were recorded during the study consisted of 12 individuals divided into 3 age groups, namely the adult, adolescent, and juvenile age groups. The results showed that the daily activity of orangutan was observed on 36 species of trees with the greatest frequency found on Garcinia sp. and Syzigium sp. accounted for33% each. The female orangutans were found to be more dominant in feeding activities (3.93 per day), while male orangutans spent more time for resting activities (4.56 hours per day). The utilization of vertical space in young male orangutans took place in tall trees and eating activities occurred at an altitude of 33.6 m. On average, teenage female orangutans choose tree to make their nests in trees 30 m high.

Home range establishment and the mechanisms of philopatry among female Bornean orangutans (Pongo pygmaeus wurmbii) at Tuanan

Female orangutans exhibit natal philopatry, living in stable home ranges that overlap with those of their maternal relatives. Using data collected from 2003 to 2017 at Tuanan in Central Kalimantan, Indonesia, we take a longitudinal approach to better understand the mechanisms of female philopatry and the factors that influence the home range establishment process of young female orangutans (Pongo pygmaeus wurmbii). Data on movement and sociality were collected during nest-to-nest focal follows of individual orangutans; four young nulli/primiparous females, their three multiparous mothers, and seven other unrelated adult females living in the same area. Our results show that a young female goes through an ‘exploration phase’, beginning when she is an independent immature and lasting through her adolescence, characterized by an increase in home range size and distance travelled each day. This exploration is facilitated by high resource availability and association with adult males. A young female maintains a high degree of overlap with her natal range but gradually decrease the degree of overlap with her mother’s concurrent range. By the time she is a sexually active adolescent, a young female and her mother share as much overlap as a young female does with other related adult females, although she continues to associate more with her mother than with them, even after the birth of her first offspring. Our findings indicate that the high habitat productivity and high orangutan population density of Tuanan lead to a high degree of life-time site fidelity and overlap among maternal kin. The mechanisms of philopatry and the process of home range establishment among solitary animals with slow life histories are difficult to study and poorly understood for most species. We investigated this process among female Bornean orangutans, using a unique long-term data set comprising 15 years of social and spatial data. We analysed changes in the ranging and association patterns of young female orangutans as they developed, matured and became mothers. We found that females went through a post-dependence phase of exploration characterized by an increase in range size and day journey length, and then settled into home ranges that overlapped highly with their mothers and other female kin, though they associated preferentially with their mothers. Our results illuminate the extreme long-term site fidelity of these female orangutans and emphasize the ecological and social importance of female philopatry among orangutans.

Gynaecological diagnosis by ultrasound and the measurement of urinary sex steroid hormones in female orangutans.

Gynaecological diagnoses were carried in three adult female orangutans (Pongo spp.) using ultrasound, and their estrous states were estimated by measuring urinary sex steroid hormone concentrations using enzyme immunoassay. Ultrasound diagnosis revealed that the endometrial thickness and follicle size were correlated with the oestrogen‐3‐glucuronide concentrations in the follicular phase. In addition, administration of the ovulation inducer human chorionic gonadotropin (hCG) had the strongest effect on the pregnanediol‐3‐glucuronide (PdG) concentration when the follicle size was 22.3 mm, suggesting that the follicle reaches this size before ovulation. The similarity between this and the maximum ovarian follicle size in humans (approximately 20 mm) indicates that the ancestral reproductive characteristics may have been retained in these species.

Sociosexual behavioral patterns involving nulliparous female orangutans (Pongo sp.) reflect unique challenges during the adolescent period.

The primate adolescent period is characterized by a series of changes in physiology, behavior, and social relationships. Orangutans have the slowest life history and the longest period of dependency of all primates. As members of a semisolitary species with high levels of sexual coercion, adolescent female orangutans face a unique combination of challenges when achieving independence from their mother. This study examined the mating behavior of adolescent female orangutans and compared it with that of adult females to assess whether mating behavior reflects distinct strategies at these different points in the life cycle. Data were collected in Gunung Palung National Park on the island of Borneo over 20 years. Mating events from adolescent (n = 19) and adult females (n = 26) were scored and compared. Adolescent female mating events had significantly higher mating scores (indicating more proceptivity) than those of adult females (β = 1.948, p = .001). Adolescent females also engaged in elaborate sociosexual interactions with different flanged males, behaviors that were never observed during mating events of adult females. These interactions involved characteristic behavior on the part of both the adolescent females and the flanged males. Given these findings and the documentation of similar accounts of adolescent female-flanged male mating from the island of Sumatra, we propose that adolescent female orangutans display distinctive behavioral repertoires throughout the genus Pongo which serves to overcome male ambivalence toward nulliparous females, establish familiarity, and evaluate coercive tendencies in flanged males. We suggest that these behavioral patterns are an integral part of female social development in a female philopatric, but highly dispersed species where consistent social support is absent after ranging independence is achieved.

Weissella, a novel lactic acid bacteria isolated from wild Sumatran orangutans (Pongo abelii).

Aims:This study aimed to isolate and identify lactic acid bacteria (LAB) in wild Sumatran orangutans to provide more information about LAB diversity derived from Sumatran orangutan feces.Materials and Methods:Fecal sampling from three female orangutans, around 35 years old, was carried out in the wild forest areas at the research station of Suaq Belimbing Gunung Leuser National Park located in the South Aceh district. Orangutan fecal samples were taken in the morning when the orangutans first defecated. The orangutans were above the tree, which is approximately 12-15 m from the ground where feces were found.Results:Fermentation testing using the API 50 CHL Kit showed that OUL4 isolates were identified as Lactococcus lactis ssp. lactis with an identity value of 73.5%. Homology analysis demonstrated that the OUL4 isolates have 93% similarity to Weissella cibaria, and phylogenetic trees constructed using Mega 7.0 also showed that OUL4 isolates are related to W. cibaria.Conclusion:These results show that there is a difference in identification between biochemical testing with API kits and molecular analyses on LAB isolates from wild Sumatran orangutans. Based on 16S rRNA gene homology, the OUL4 LAB isolates from wild Sumatran orangutans have 93% homology to W. cibaria.

Are Male Orangutans a Threat to Infants? Evidence of Mother–Offspring Counterstrategies to Infanticide in Bornean Orangutans (Pongo pygmaeus wurmbii)

Sexually selected infanticide by males is widespread in primates. Female primates employ a variety of strategies to reduce infanticide risk. While infanticide has never been directly observed in wild orangutans (Pongo spp.), their slow life history makes infants vulnerable to infanticide. The mating strategies of female orangutans include polyandrous and postconceptive mating that may serve to increase paternity confusion, an infanticide avoidance strategy. Here, we investigate whether female orangutans alter their social interactions with males as another infanticide avoidance strategy. We hypothesize that females with younger offspring avoid males and that the distance between mother and offspring decreases in the presence of males. We use long-term behavioral data collected between 1994 and 2016 from Bornean orangutans (Pongo pygmaeus wurmbii) in Gunung Palung National Park, Indonesia, to test whether the sexual selection hypothesis for infanticide helps explain aspects of orangutan social behavior. We found that mothers with offspring 6 yr. old and females without offspring. In addition, the distance between a mother–offspring dyad showed a statistically significant decrease in the presence of males, but not females. Our results are consistent with the hypothesis that female orangutans employ strategies to reduce infanticide risk in their social interactions. Because orangutans have a high fission–fusion dynamic, they have flexibility in manipulating social interactions as a counterinfanticide strategy. Our results suggest that infanticide by males is a selective pressure shaping female orangutan social behavior.

Orangutans' Comprehension of Zoo Keepers' Communicative Signals.

Simple SummaryMost modern zoos work towards the promotion of captive animals’ welfare. One way of achieving this is by encouraging cooperative interactions between keepers and zoo animals, for instance during sessions of conditioning training. To be most effective, communication between them should use those channels that are most useful to the animals. In this study, we asked whether captive orangutans were capable of understanding keepers’ instructions when they were employing words only, gazes only, gestures only, or all signal types combined. Our results indicate that the subjects only need gestures to respond to the keepers’ instructions. In two other experiments, we examined why gestures were so effective. One hypothesis was that they resemble what they refer to. However, we found no indication that gestures providing iconicity or even pointing could help orangutans acquire associations between a new gesture and referent. Our results suggest that, among human communicative signals, captive orangutans would prefer gestures. Why this is the case should be the focus of future research.Zoological institutions often encourage cooperative interactions between keepers and animals so as to promote animals’ welfare. One useful technique has been conditioning training, whereby animals learn to respond to keepers’ requests, which facilitates a number of, otherwise sensitive, daily routines. As various media have been used to convey keepers’ instructions, the question remains of which modality is best to promote mutual understanding. Here, we explored this question with two captive female orangutans. In the first experiment, we compared orangutans’ understanding of previously acquired instructions when those were performed with verbal signals only, gazes only, gestures only, and when all those modalities were combined. Our results showed that gestures were sufficient for successful comprehension by these two apes. In the second experiment, we asked whether this preference could be driven by the non-arbitrary relationship that gestures bear to what they refer to, through iconicity or pointing. Our results revealed that neither iconicity nor pointing helped the subjects comprehend the keepers’ instructions. Our results indicate a preference for instructions given through gestural signals in two captive female orangutans, although its cause remains elusive. Future practice may encourage the use of gestures in communication between keepers and orangutans in general or potentially other animals.

AKTIVITAS SOSIAL ORANGUTAN (Pongo pygmaeus wurmbii) DI STASIUN PENELITIAN CABANG PANTI TAMAN NASIONAL GUNUNG PALUNG KABUPATEN KAYONG UTARA KALIMANTAN BARAT

Diverse types of habitat were interesting objects which existed in the Cabang Panti Research Station, due to it, the researcher was interested to investigate about Orangutan’s activities in one type of habitat and the researcher focused on Orangutan’s social activities. The purpose of this study was to determine the social behavior of orangutans in the Research Station cabang panti gunung palung national park in Kayong Utara District, West Kalimantan. The used method was focal animal sampling, a method of observing and recording the behavior of one individual over a certain period of time while the object must be visible during observation and the data collection in this study focused on adult male and / or female orangutans as the objects in the study. The length of observation time of the target orangutan in this study was + 13 hours per day for 5 days by concerning the daily activities of orangutans from waking up to sleeping. Based on the results of the observed object, there were 2 individuals namely Walimah which was an adult female and Julian which was an adult male. Overall, during the observations, the two individuals were following each other, the target orangutan “Walimah” had high eating activities throughout the day reaching 41,31% followed by movement activities 25,18%, then resting 23,18%, self-action 9,96%, and social activity 0,37%. While the target orangutan "Julian" carried out high resting activities throughout the day reaching 40,15% followed by eating activities 28,45%, movement 22,71%, self-action 7,73%, and social activity 0,97%.Keywords: Cabang Panti, Orangutan, Social Activity

An Enigmatic Hypoplastic Defect of the Maxillary Lateral Incisor in Recent and Fossil Orangutans from Sumatra (Pongo abelii) and Borneo (Pongo pygmaeus)

Developmental dental pathologies provide insight into health of primates during ontogeny, and are particularly useful for elucidating the environment in which extant and extinct primates matured. Our aim is to evaluate whether the prevalence of an unusual dental defect on the mesiolabial enamel of the upper lateral incisor, thought to reflect dental crowding during maturation, is lesser in female orangutans, with their smaller teeth, than in males; and in Sumatran orangutans, from more optimal developmental habitats, than in those from Borneo. Our sample includes 49 Pongo pygmaeus (87 teeth), 21 P. abelii (38 teeth), Late Pleistocene paleo-orangutans from Sumatra and Vietnam (67 teeth), Late Miocene catarrhines Lufengpithecus lufengensis (2 teeth), and Anapithecus hernyaki (7 teeth). Methods include micro-CT scans, radiography, and dental metrics of anterior teeth. We observed fenestration between incisor crypts and marked crowding of unerupted crowns, which could allow tooth-to-tooth contact. Tooth size does not differ significantly in animals with or without the defect, implicating undergrowth of the jaw as the proximate cause of dental crowding and defect presence. Male orangutans from both islands show more defects than do females. The defect is significantly more common in Bornean orangutans (71 %) compared to Sumatran (29 %). Prevalence among fossil forms falls between these extremes, except that all five individual Anapithecus show one or both incisors with the defect. We conclude that maxillary lateral incisor defect is a common developmental pathology of apes that is minimized in optimal habitats and that such evidence can be used to infer habitat quality in extant and fossil apes.

Saliva Crystallization Occurs in Female Bornean Orangutans (Pongo pygmaeus): Could It Be a New Option for Monitoring of Menstrual Cycle in Captive Great Apes?

Saliva crystallization was previously studied in both humans and animals with various results. The study aimed to confirm of the presence of saliva crystallization in female Bornean orangutans (Pongo pygmaeus), to evaluate the quality of samples which were collected from animals and processed by keepers, and to test preliminarily if the saliva crystallization could be connected with menstrual cycle and could serve as a cheap, quick and simple method for the basic monitoring of their reproductive status. The research was carried out from September 2014 to January 2015. Sampling of saliva was done in three female orangutans from three zoological gardens (Dvur Kralove, Usti nad Labem, Bojnice) daily, mostly by tongue prints on glass slides with ground edges or by sampling directly from the mouth using plastic spoons from which the saliva was transferred onto glass slides. Samples were evaluated by light microscopy with ×400 magnification. The quality of the sample and type of crystallization was assessed for two different approaches. In total, 246 samples were evaluated. We confirmed the presence of saliva crystallization in orangutans. The quality of samples was variable however acceptable. Unfortunately, it was impossible to detect exact fertile period in two females. However in one orangutan female, when the crystallization was evaluated by the approach typically used in humans, we discovered that saliva crystallization during the fertile period significantly differed from saliva crystallization in the non-fertile period. This points out the possibility of using saliva crystallization for detection of the fertile period in orangutans. However, further research was recommended.

The dark side of the red ape: male-mediated lethal female competition in Bornean orangutans

Female Bornean orangutans (Pongo pygmaeus wurmbii) are mainly solitary and philopatric, leading to adult female relatives sharing adjacent and overlapping home ranges. Females tend to be intolerant of unrelated females, with whom they also may have overlapping home ranges. However, fights that lead to injuries are extremely rare and lethal aggression had never been observed. Here, we report the first case of lethal female-female aggression during over 26,000 h of focal data collected on adult females at Tuanan, Central Kalimantan: A young female, who had recently lost her infant, attacked an old resident female. The interaction’s unique feature was that the attacking female was supported by an unflanged male, who had been in consort with her during the week preceding the attack and was responsible for the lethal injuries to the victim. The victim received protection from a flanged male who was probably attracted to the noise generated by the fight. We conclude that even in a species in which coercion is frequently observed in male-female interactions, female leverage over males can coax males into providing services, such as coalitionary support.