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See detailFeeding and ranging behavior of northern pigtailed macaques (Macaca leonina): impact on their seed dispersal effectiveness and ecological contribution in a tropical rainforest at Khao Yai National Park, Thailand
Albert, Aurélie ULg

Doctoral thesis (2012)

Southeast Asia experiences an exceptional loss of natural habitat due to a deforestation rate that strongly increased during the last decades. The first consequence is the loss of many animal and plant ... [more ▼]

Southeast Asia experiences an exceptional loss of natural habitat due to a deforestation rate that strongly increased during the last decades. The first consequence is the loss of many animal and plant species, threatened by their habitat degradation and by the loss of interactions necessary to the survival of the whole ecosystem. Large mammals and birds populations, the principal dispersal agent of some plant species, already collapsed massively due to hunting and habitat fragmentation and now threaten to die out. Among the large frugivorous species, primates are particularly vulnerable. Only few species, such as macaques, are able to survive in some man-made habitats, due to their opportunistic life-style. But, in the long term, habitat destruction, hunting and capture for local trade threaten their survival. The extinction of primates in Southeast Asian forests would be disastrous for many plant species as primates are among the major seed-dispersal agents. The study of Macaca, the only Cercopithecinae genus in Southeast Asia, could provide a better understanding of the role of cheek-pouched monkeys in tropical rainforest maintenance and restoration. In this study, we chose to focus on northern pigtailed macaques (Macaca leonina) as few studies were carried out on this species, making data concerning its ecology and behavior highly limited. Their seed dispersal capacity, although unknown, is potentially high and pigtailed macaques could be as good seed dispersers as sympatric frugivores. They seem to eat a large number of fruits of many plant species, process seeds with care, and range daily over large areas. Moreover they could have a role in forest maintenance and regeneration given that they seem to eat species with all seed sizes, belonging to all plant life forms present in the forest, and they are able to cross various habitat types (primary as well as secondary forests). After providing an outline of our current knowledge on seed dispersal by Cercopithecinae species and their specific role in forest regeneration, our aim was to highlight the importance of northern pigtailed macaques on seed dispersal and thus on forest regeneration by studying (1) how their eco-ethological characteristics can make them effective dispersers, from a quantitative and a qualitative point of view, (2) how the influence of biotic factors, such as resources and predation, on their activities and movements may impact their seed dispersal effectiveness, and (3) what role Macaca spp. can have in a seed dispersal assemblage. While following a troop of northern pigtailed macaques habituated to humans in Khao Yai National Park, Thailand, we recorded their behavior, travels, and consumed items, from dawn to dusk. Moreover, we studied the spatio-temporal distribution of fruits included in their diet, and the characteristics of their sleeping sites. Finally, we performed germination and viability tests on ingested seeds. Results showed that northern pigtailed macaques could disperse thousands of seeds, up to 58 mm in length, coming from the 126 fruit species they eat. Especially, they could disperse them from primary to secondary forest, thanks to handling techniques such as swallowing, spitting and dropping. Finally, the seed passage through their digestive tract mostly had a neutral or positive effect on seed germination and viability. Macaques observed in this study satisfied therefore most requirements defining effective seed dispersers in both quantitative and qualitative terms and we can conclude to the potential importance of Macaca leonina in the tropical rainforest regeneration. To confirm the seed dispersal effectiveness of M. leonina, we needed to make sure that its ranging behavior did not negatively affect dispersed seeds. Moreover, given the importance of human food in their diet, we wondered if this resource had a negative impact on seed dispersal. Our results showed that northern pigtailed macaques adapted their ranging pattern according to fruit availability. Moreover, during fruit scarcity, they shifted their diet from frugivorous to omnivorous with an important part of human food. However, human food did not seem to have an impact on seed dispersal in high fruit abundance periods where macaques had a large home range, traveled long distances and ate mainly fruits. However, in low fruit abundance periods, macaques decreased their home range size, traveled shorter distances and ate mainly human food. This latter could have a negative impact on the seed dispersal of some rare fructifying species. However, these species were eaten by many other animal species able to provide good dispersal services. Then, we showed that sleeping sites characteristics and pre-sleep behavior in M. leonina were influenced by the proximity of resources and the risk of predation. Given that macaques used few sleeping sites, defecated when they woke up and that all troop members slept concentrated in a small area, we think that they created a high seed density below the sleeping trees. This may be harmful for some seed species but may be beneficial for the ecosystem. Moreover, this pattern may be shown in other effective seed dispersers in the park. So as harmful for seeds it may be, it does not make pigtailed macaques less effective than other frugivores. Finally, we demonstrated that Macaca species are important associates in the seed dispersal assemblage found in Southeast Asian forests. Indeed they may disperse most plant species, usually more efficiently dispersed by other frugivores, and thus provide a significant complement in term of dispersal quantity. Moreover, they are sometimes the only frugivores able to disperse the seeds of some species, mainly large-seeded and/or protected ones, and may thus bring them a vital dispersal service. [less ▲]

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See detailContext-related vocalizations in African grey parrots (Psittacus erithacus)
Giret, Nicolas; Albert, Aurélie ULg; Nagle, Laurent et al

in Acta Ethologica (2012), 15

A few animal species are capable of vocal learning. Parrots are well known for their vocal imitation abilities. In this study, we investigated whether African grey parrots (Psittacus erithacus) emit ... [more ▼]

A few animal species are capable of vocal learning. Parrots are well known for their vocal imitation abilities. In this study, we investigated whether African grey parrots (Psittacus erithacus) emit specific vocalizations in specific contexts. We first described the vocal repertoire and its ontogenesis of four captive grey parrots. After a comparison with vocalizations emitted by wild and other captive African grey parrots, we observed that only three call categories were shared by all grey parrots populations, suggesting that isolated populations of parrots develop population-specific calls. Then, we artificially provoked ten different contexts and recorded vocalizations of four captive grey parrots in these situations. Parrots predominantly emitted call categories in some contexts: distress, protestation, alarm, asking (i.e. emitted when a bird wanted something from an experimenter and contact calls. These results suggest that some calls are learned and can be used in specific contexts. [less ▲]

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See detailSeasonal variations of ranging pattern in pigtailed macaques: influence of wild and human resources
Albert, Aurélie ULg; Savini, Tommaso ULg; Huynen, Marie-Claude ULg

Conference (2011, September)

Numerous studies have highlighted the influence of food availability on primate behaviour. Our research aims at understanding the ranging pattern of a troop of northern pigtailed macaques (Macaca leonina ... [more ▼]

Numerous studies have highlighted the influence of food availability on primate behaviour. Our research aims at understanding the ranging pattern of a troop of northern pigtailed macaques (Macaca leonina) living around the visitor center of the Khao Yai National Park, Thailand. The frugivorous pigtailed macaques are supposed to adapt their ranging pattern to the spatio-temporal distribution of fruiting trees. However, the presence of humans, and thus, of human food, may also have an impact on their home range size and location. We followed the troop during 12 months and recorded its diet and progression within the home range (GPS points every 30 minutes). On monthly kernels defining the home range surface, we superimposed a grid of 110x110 m cells. We analysed the spatio-temporal distribution of fruiting trees in botanical transects and converted it into a food abundance index (FAI). Given their semi-terrestriality decreasing travel costs, we predicted that macaques should increase their range during the period of low fruit abundance to gather a sufficient amount of high-quality food (fruits). To the contrary, our results showed that the size of the troop’s home range decreased during fruit scarcity (dry season). The diet analysis showed that during this period, macaques used human food, a high-quality resource, as fallback food which concentration around human settlements made the long travel no more necessary. Alternately, in period of fruit abundance, a correlation between the FAI and the number of GPS points from macaques for each home range cell showed that macaques spent more time in places with a higher abundance of some fruit species, in particular some considered as important in their diet. Finally, in this peculiar situation of macaques living close to human managed areas, both wild and human resources’ spatio-temporal distribution influence the size and location of the troop’s home range [less ▲]

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See detailFinding good acoustic features for parrot vocalizations: The feature generation approach
Giret, Nicolas; Roy, Pierre; Albert, Aurélie ULg et al

in Journal of the Acoustical Society of America (2011), 129

A crucial step in the understanding of vocal behavior of birds is to be able to classify calls in the repertoire into meaningful types. Methods developed to this aim are limited either because of human ... [more ▼]

A crucial step in the understanding of vocal behavior of birds is to be able to classify calls in the repertoire into meaningful types. Methods developed to this aim are limited either because of human subjectivity or because of methodological issues. The present study investigated whether a feature generation system could categorize vocalizations of a bird species automatically and effectively. This procedure was applied to vocalizations of African gray parrots, known for their capacity to reproduce almost any sound of their environment. Outcomes of the feature generation approach agreed well with a much more labor-intensive process of a human expert classifying based on spectrographic representation, while clearly out-performing other automated methods. The method brings significant improvements in precision over commonly used bioacoustical analyses. As such, the method enlarges the scope of automated, acoustics-based sound classification. [less ▲]

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See detailSleeping Site Selection and Presleep Behavior in Wild Pigtailed Macaques
Albert, Aurélie ULg; Savini, Tommaso ULg; Huynen, Marie-Claude ULg

in American Journal of Primatology (2011), 73

Several factors are likely to control sleeping site selection and presleep behavior in nonhuman primates, including predation risk and location of food resources. We examined the effects of these factors ... [more ▼]

Several factors are likely to control sleeping site selection and presleep behavior in nonhuman primates, including predation risk and location of food resources. We examined the effects of these factors on the sleeping behavior of northern pigtailed macaques (Macaca leonina). While following a troop living in the surroundings of the Visitor Center of Khao Yai National Park (Thailand), we recorded the physical characteristics and location of each sleeping site, tree, the individuals’ place in the tree, posture, and behavior. We collected data for 154 nights between April 2009 and November 2010. The monkeys preferred tall sleeping trees (20.97SD 4.9 m) and high sleeping places (15.87SD 4.3 m), which may be an antipredator strategy. The choice of sleeping trees close to the last (146.77SD 167.9 m) or to the first (150.47SD 113.0 m) feeding tree of the day may save energy and decrease predation risk when monkeys are searching for food. Similarly, the choice of sleeping sites close to human settlements eases the access to human food during periods of fruit scarcity. Finally, the temporal pattern of use of sleeping sites, with a preference for four of the sleeping sites but few reuses during consecutive nights, may be a tradeoff between the need to have several sleeping sites (decreasing detection by predators and travel costs to feeding sites), and the need to sleep in well-known sites (guaranteeing a faster escape in case of predator attack). [less ▲]

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See detailImportance of pigtailed macaques (Macaca nemestrina leonina) in seed dispersal: impact on the ecological balance of the tropical rainforest at Khao Yai National Park, Thailand
Albert, Aurélie ULg; Huynen, Marie-Claude ULg; Savini, Tommaso ULg

Poster (2010)

Today, many countries of South-East Asia know about the alarming state of the forests existing on their territory and all agree that it is essential to save the remaining primary forest but also to enable ... [more ▼]

Today, many countries of South-East Asia know about the alarming state of the forests existing on their territory and all agree that it is essential to save the remaining primary forest but also to enable the regeneration of degraded areas, through natural or artificial reforestation. The conservation of tropical rainforests thus passes by the necessity to better understand the plant-animal interactions, and in particular, the seed dispersal process. While following a troop of pigtailed macaques (Macaca nemestrina leonina) accustomed to Man in Khao Yai National park (2 168 km ²), Thailand, we will bring important data relating to these seed dispersers potentially necessary but unfortunately vulnerable. Indeed, this vulnerable but little known species, seems to be essential to maintain forest diversity by dispersing many plant species, particularly those inaccessible to smaller frugivores. First results already show that they disperse many seed species, of all kind of size, in all forest types, from primary forest to secondary forest, thanks to various handling techniques. They also seem to show an adaptation in their daily travels according to resources availability. The next fieldworks will enable us to bring more precision in these results and their temporal variations and thus to conclude on the potential role of Macaca nemestrina in the tropical rainforest regeneration. [less ▲]

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See detailImportance of pigtailed macaques (Macaca nemestrina leonina) in seed dispersal and impact on the ecological balance of the tropical rainforest at Khao Yai National Park, Thailand
Albert, Aurélie ULg; Huynen, Marie-Claude ULg

Poster (2009, February)

The tropical rain forest is maintained thanks to a precarious balance placed under the yoke of interactions between the various animal and plant species which compose it. Among them we can find those ... [more ▼]

The tropical rain forest is maintained thanks to a precarious balance placed under the yoke of interactions between the various animal and plant species which compose it. Among them we can find those implying plants and frugivores. Although its diet is largely frugivorous, the pigtailed macaques (Macaca nemestrina leonina) have often been categorized as seed predators. However their morphology, behaviour and ecology suggest they could actually be a key-species in the dispersion of many plant species. A preliminary study by Latinne & al (2007) supported this hypothesis. The study we are planning now in continuity of Latinne’s study will take place in the Khao Yai National Park, Thailand, for three years and will focus on a troop habituated to humans. In order to establish the importance of the pigtailed macaques in the maintenance and the regeneration of the tropical rain forest, we will try to evaluate their capacity of being good seed dispersers. To do so, we will study: 1) the spatiotemporal distribution, the productivity and the characteristics of the plant species present on the home range of the studied troop, 2) the ranging patterns of the macaques within their home range, 3) their feeding behaviour, notably the fruit selection and the various modes of processing seeds, and finally 4) their impact on the viability and the germination potential of seeds. This study will require both direct observations of the macaques and semi-experimental procedures in the field, as well as laboratory control of some seed parameters. We hope the clarification of the macaques’ seed dispersal behaviour would help to re-evaluate their conservation status by recognizing them a paramount role in the maintenance of the tropical rainforest. [less ▲]

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See detailImportance des macaques à queue de cochon (Macaca nemestrina leonina) dans la dispersion des graines : impact sur l’équilibre écologique de la forêt tropicale au parc national de Khao Yai, Thaïlande
Albert, Aurélie ULg; Latinne, Alice ULg; Savini, Tommaso ULg et al

in Folia Primatologica : International Journal of Primatology = Internationale Zeitschrift für Primatologie = Journal international de Primatologie (2009)

Today, many countries of South-East Asia know about the alarming state of the forests existing on their territory and all know that it is essential to save the still existing primary forest but also to ... [more ▼]

Today, many countries of South-East Asia know about the alarming state of the forests existing on their territory and all know that it is essential to save the still existing primary forest but also to enable the regeneration of degraded areas, in particular thanks to reforestation (natural or artificial). To elucidate the role of seed dispersers and to promote their conservation are essential for the conservation of the tropical rainforests. While following a troop of pigtailed macaques (Macaca nemestrina leonina) accustomed to Man in Khao Yai National park (2 168 km ²), Thailand, we will bring important data relating to these seed dispersers potentially necessary but unfortunately vulnerable. Indeed, this species, from which very little has been studied, seems to be essential to the dispersal of many plant species, particularly those inaccessible to smaller frugivores. The results emanating from the first fieldwork already show important characteristics: the dispersal of many seed species, of all kind of size, in all forest types, from primary forest to secondary forest, thanks to various handling techniques. They also seem to show an adaptation in their daily travels according to resources availability. The next fieldworks will enable us to bring more precision in these results and their temporal variations and thus to conclude on the potential role of Macaca nemestrina in the regeneration of the tropical rainforest. [less ▲]

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See detailImportance of pigtailed macaques (Macaca nemestrina leonina) in seed dispersal: Impact on the ecological balance of the tropical rainforest at Khao Yai National Park, Thailand
Albert, Aurélie ULg; Huynen, Marie-Claude ULg

Conference (2008, October 22)

The tropical rain forest is maintained thanks to a precarious balance placed under the yoke of interactions between the various animal and plant species which compose it. Among them we can find those ... [more ▼]

The tropical rain forest is maintained thanks to a precarious balance placed under the yoke of interactions between the various animal and plant species which compose it. Among them we can find those implying plants and frugivores. Today, no study was still undertaken on the pigtailed macaques (Macaca nemestrina leonina) because they are considered seed predator. However, recent studies showed that it could actually be a key-species in the dispersion of many plant species. The study will take place in the Khao Yai National park (2,168 km²), Thailand. We will follow a troop of forty individuals habituated to humans and already well-known. Our goal will be to establish the importance of the pigtailed macaques in the maintenance and the regeneration of the tropical rain forest. Thus we will try to evaluate their capacity of being good seed dispersers. In this purpose we will study: 1) the spatiotemporal distribution, the productivity and the characteristics of the plant species present on the home range of the studied troop, 2) the ranging patterns of the macaques within their home range, 3) their feeding behaviour, notably the fruit selection and the various modes of processing seeds, and finally 4) their impact on the viability and the germination potential of seeds. The study of seed dispersal by these macaques would enable us to step further into the understanding of this environment and, perhaps, to improve the destiny of the pigtailed macaques, species now characterized as “vulnerable”, in recognizing them a paramount role in the conservation of their habitat. [less ▲]

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