Frugivory and seed dispersal by northern pigtailed macaques, Macaca leonina, in Thailand

in International Journal of Primatology (2013), 33

Dispersal and regeneration capacity of large-seeded tree species in a forest-savanna mosaic in Western DR Congo

Poster (2012)

It is widely recognized that the Congo Basin is affected by numerous anthropogenic pressures. A number of studies proved that hunting and forest fragmentation diminish the diversity and abundance of large ... [more ▼]

It is widely recognized that the Congo Basin is affected by numerous anthropogenic pressures. A number of studies proved that hunting and forest fragmentation diminish the diversity and abundance of large vertebrates, more specifically, of large frugivores. The depletion of those animals can directly affect large-seeded tree species as large seeds closely depend on the community of large frugivorous vertebrates for their dispersal. Then, the disruption of animal mediated seed dispersal is thought to deeply impact the plant regeneration capacity. The forest-savanna mosaic situated in Western DR Congo is an ecotone characterized by naturally occurring forest fragments which are also subject to numerous anthropogenic pressures. Those are very likely to disrupt seed dispersal mechanisms and to alter forest regeneration processes. To date, few studies have considered the effect of such an ecosystem on plant-animal interaction dynamics such as seed dispersal, and none have been done in this region. This study will examine if the early stages of regeneration of the large-seeded tree species Anonidium mannii, namely the dispersal capacity and seedling establishment is affected by forest fragment size. We predict that the small fragment size will negatively affect the regeneration capacity of this species. To test this assumption, we will work along a gradient of forest fragment sizes to define the composition of the seed disperser communities. For each disperser assemblage, we will evaluate the quantitative capacity of seed dispersal by combining direct focal observations and camera trapping. A literature review on each disperser species seed retention time and habitat use will allow the computation of the seed dispersal kernels. We will also evaluate the effect of seed ingestion by a presumably important seed disperser, the bonobo, Pan paniscus, on its germination capacity. Seeds will be collected from dung to evaluate the effect of seed ingestion on the rate and velocity of germination. Finally, we will study the predation pressure exerted on dispersed and non-dispersed seeds and seedlings by setting up two sets of seeds below the canopy of parent trees and away from any conspecific trees. One set will be dispersed unprotected to seed predators; another one will be enclosed in a cage and permit seeds to germinate, allowing us to evaluate the herbivores pressure on seedlings. [less ▲]

Seasonal variations of ranging pattern in pigtailed macaques: influence of wild and human resources

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 ▲]

Reproductive failure, possible maternal infanticide and cannibalism in wild moustached tamarins, Saguinus mystax

in Primates : Journal of Primatology (2011), 52

Tamarins and dung beetles: an efficient diplochorous dispersal system in the Peruvian Amazonia

in Biotropica (2011), 43(1), 84-92

Dung beetles fulfil several key ecosystem functions but their role as secondary seed dispersers is probably one of the most complexes because several factors can diversely affect the seed / beetle ... [more ▼]

Dung beetles fulfil several key ecosystem functions but their role as secondary seed dispersers is probably one of the most complexes because several factors can diversely affect the seed / beetle interaction. Little is known about the dung beetle communities and their influence on occurrence and depth of burial of seeds dispersed in small faeces. The aim of this study was to investigate the effects of various factors (type of faeces, defecation pattern, season, habitat, seed characteristics) on dung beetle community (composition, number and size of individuals and species) and its consequences on occurrence and depth of burial of seeds primarily dispersed by two tamarin species. We captured dung beetles in a Peruvian rainforest with 299 dung-baited pitfall traps to characterize the dung beetle community. Seed burial occurrence and depth were assessed by marking, in situ, 551 dispersed seeds in faeces placed in a cage. We observed a significant effect of the amount of dung, season, time of defecation, and habitat on the number of individuals and species of dung beetles, as well as on seed burial occurrence and depth, while the type of faeces only significantly influenced the number and the size of dung beetles. Surprisingly, there was no significant effect of seed length, shape, and mass neither on seed burial occurrence, nor on burial depth. We highlighted that dung beetles compete for the first access to the resource on small faeces rather than for space for the building of their nest as observed on large faeces. [less ▲]

Importance of pigtailed macaques (Macaca nemestrina leonina) in seed dispersal: impact on the ecological balance of the tropical rainforest at Khao Yai National Park, Thailand

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 ▲]

Importance 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

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 ▲]

Measuring home-range quality in the frugivorous gibbon (Hylobates lar)

Conference (2009)

Short-term post-dispersal fate of seeds defecated by two small primate species (Saguinus mystax and Saguinus fuscicollis) in the Amazonian forest of Peru

in Journal of Tropical Ecology (2009), 25

Post-dispersal fate of seeds dispersed by large primates is well studied but little is known about this process in small frugivores like tamarins. This study in the Amazonian forest of Peru aimed at ... [more ▼]

Post-dispersal fate of seeds dispersed by large primates is well studied but little is known about this process in small frugivores like tamarins. This study in the Amazonian forest of Peru aimed at investigating if characteristics related to the defecation patterns of tamarins (Saguinus mystax and Saguinus fuscicollis) affected short-term post-dispersal seed fate, through secondary seed dispersal by dung beetles and removal by seed predators. Data on dung beetle activity were based on direct observations of 49 defecations while seed fate was studied using semi-controlled experiments (N = 458 for secondary dispersal and N = 398 for predation). Tamarins produce small defecations with a low number of seeds. Thirty-five per cent of defecations were visited by an average of 1.5 dung beetles that usually transport the faeces as pellets. Twenty-four per cent of seeds were buried by beetles at a mean depth of 3.5 cm. With increasing quantities of faecal matter, the probability of secondary seed dispersal increased but not the depth of burial. Seed predation pressure was low (17.6%) after 4 d and higher in faeces of S. mystax than in faeces of S. fuscicollis. Despite their small size, tamarins could be considered as high-quality seed dispersers, with a potential role for forest regeneration. [less ▲]

Diet, habitat use, and seed dispersal by a pigtail macaque (Macaca nemestrina leonina) troop in Khao Yai National Park (Thailand)

Conference (2008, April 23)

While studying the influence of human proximity on the ecology of pigtail macaques, a species not well documented in continental Thailand, we collected data on ranging and foraging behaviours of a troop ... [more ▼]

While studying the influence of human proximity on the ecology of pigtail macaques, a species not well documented in continental Thailand, we collected data on ranging and foraging behaviours of a troop of Macaca nemestrina leonina living in the surroundings of Khao Yai National park tourist centre. We present here data suggesting a role as seed dispersers for the pigtails, role which has not been considered yet when analysing the importance of the frugivorous community in forest regeneration. Such a role might be however expected based on the highly frugivorous diet of the macaques, the presence of cheek pouches, and the relatively long distance they travel daily. The studied troop counts about 40 individuals, with 3 adult males for 9 adult females, and occupies a 100 ha home range with sleeping sites close to the tourist facilities. Macaques spent about 30% of their days in primary forests, and more than 60 percent in secondary forest and open areas. They consume a certain proportion of human food (6.4%), but spend most time foraging for wild food in the surrounding forest. Fruits count for an important part of their diet (76%) and, indeed, the faeces analysis reveals the presence of a high number of seeds, which size ranges up to above 15mm. Their viability was assessed using the cut-test and Tetrazolium immersion, showing a high percentage of viable seeds in the samples. Three series of seeds (defecated, spat, and control seeds) placed in germination boxes reached a high germination rate, with no uniform significant differences between defecated, spat and control seeds. Seeds without pulp, a frequent case when macaques reject them after transport and processing, seem to be more likely to germinate than seeds rejected with their pulp directly under the parent tree. These results suggest altogether that pigtail macaques are potential seed dispersers, an important factor in regard of their regular use of degraded habitat zones. [less ▲]