Primate topics - Operation Wallacea

Primate topics

Country codes: HO (Honduras), IN (Indonesia), MA (Madagascar), ME (Mexico), PE (Peru), SA (South Africa)

MA41 The impact of human-animal-interactions on the behaviour of lemurs in Mahamavo, NW Madagascar

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The scientific study of human-animal interactions (HAI) has developed drastically over the years from initial investigations into agricultural, companion and now zoo animals. These investigations focus on captive managed animals, which are bred in these conditions and potentially more accustomed to human presence. Wild animals, however, are not and with the number of HAI between wild animals and humans due to an increase in eco-tourism and general living in and around areas normally habited by wild animals, these have a potential to have a greater impact and influence conservation strategies of threatened species. Studies have highlighted that for various species, these close living arrangements and/or close encounters between wild animals and humans can have significant negative effect on the animals’ spatial response, reproductive success and behaviours. Current research has investigated human presence and disturbance impacts of a handful of bird and reptile species, the hermit crab and ten species of North American mammal, but no current research has investigated the potential impacts on threatened primate species or species that have the potential for ecotourism impact. This project aims to investigate what, how and why impacts of human presence have on a variety of lemur species living in the forests.

Extended Project Summary

MA42 Regional biogeography, ecology and behaviour of nocturnal lemurs in the dry deciduous forest of northwestern Madagascar

Lemurs are 100% endemic to Madagascar and are confined to the remaining forest habitats of the island. They are a highly diverse taxonomic group (>100 species) and at the same time the most threatened group of mammals with about 94% of all assessed species being categorized as either vulnerable, endangered, or critically endangered (IUCN, July 2012). In this situation it is of utmost importance to understand their local and regional distribution as well as the behavioural constraints, ecological plasticity and ecological requirements of each lemur species in order to determine their vulnerability towards becoming extinct in the near future. Among the nine lemur species that have been reported from the Mariarano area, six are nocturnal (Microcebus murinus, M. ravelobensis, Cheirogaleus medius, Phaner pallescens, Lepilemur edwardsi, Avahi occidentalis). Nocturnal lemurs are generally much less studied than their diurnal cousins but face the same anthropogenic threats. They are therefore chosen as models for this project. The aim of this research is to study the abundance, spatial distribution, ecology, and behaviour of three different nocturnal lemur genera (Microcebus spp., Lepilemur edwardsi, Avahi occidentalis) in various forest fragments in the Mahamavo region, northwestern Madagascar.

Extended Project Summary

ME49 Spider monkey grouping patterns, habitat use and behaviour

Spider monkeys are frugivorous primates that live in complex societies characterised by high degree fission fusion dynamics whereby members of the same community are rarely all together and spend their time in fluid subgroups that constantly change in size and composition. Subgroup size is adjusted to food patch size and when fruit is abundant the spider monkeys can be found in large groups. Group size and composition can have a notable effect on activity budgets, ranging and social interactions, particularly as there are notable sex-differences in the quality of social relationships and the type of social interactions exchanged by males and female. A large community of spider monkeys in the Calakmul Biosphere Reserve has been studied each summer since 2013. The summer months are associated with the onset of rainy season and high fruit production resulting in large subgroups of spider monkeys. However in 2014 the reserve suffered a severe drought and during this time virtually no fruit was available. Using the long-term data set students can investigate changes to ranging patterns, subgroup composition and the associated effect on rates of social interactions in relation to rainfall patterns and food availability. Another project could focus on spider monkey activity and habitat use. Spider monkeys can have large home ranges that encompass different forest types, but it is not clear if they use all forest types for food and shelter. An investigation of how spider monkeys use the different forest types will determine whether spider monkey populations could survive in disturbed areas with limited availability of high forest. Activity budget data will be recorded using instantaneous scan sampling, noting the behaviour of each individual in view, the GPS location and forest type. Subgroup composition will be recorded in real time throughout the day and all occurrences of social interactions will be recorded noting the individuals involved, behaviour and context.

Extended Project Summary

PE63 Population monitoring and habitat preferences of primates in the Pacaya-Samiria Reserve

As a result of seasonal variation in rainfall in the Andean headwaters, the rivers of the Amazon basin are subject to large fluctuations in water levels throughout the year that flood the surrounding forest. The Pacaya-Samiria National Reserve is no exception, with as little as 2% of land in the reserve above water at the height of the flooded season. The forests of the National Reserve flood as the waters rise between December and June, and the onset of rainfall coincides with high fruit production that is the primary dietary component of a wide number of primate species. In recent years these normal seasonal changes in rainfall patterns have become more intense, which has been tentatively attributed to climate change. Consequently, dry and rainy seasons are more pronounced resulting in unpredictable food supply and the extent to which primate populations can adapt to these changes is not yet known. Investigation of the impact of changing rainfall patterns on the abundance, diversity and distribution of primates in the Pacaya-Samiria Reserve will involve line transect surveys across forest types that flood to varying degrees with distance sampling to calculate density of primate species. These data may be added to the long-term data set to investigate changes to primate abundance over time in relation to water levels. Forest structure and fruit availability data may be collected from a series of habitat plots spaced equidistantly along each transect. Each primate encounter can then be linked to the nearest habitat plot along the transect providing a corresponding set of habitat variables for primate record. From this, habitat preferences of each species may be calculated and the habitat variables affecting primate abundance and diversity at each plot can also be investigated.

Extended Project Summary

PE64 Niche separation in tamarins, howler monkeys, squirrel monkeys and other primates in the Peruvian Amazon

Multiple primate species can be found in rainforest habitats such as the Peruvian Amazon. In order to combat competition associated with several similar species living in close proximity, each species has evolved to occupy a specific niche within the habitat. These adaptations include differences in dietary requirements (frugivorous, folivorous and insectivorous primates), preference for different habitat types within the forest (e.g. seasonally flooded forest, upland forest and palm swamps) and variation in habitat use within the same forest type (e.g. occupying different heights within the forest canopy or variation in activity budgets). Twelve species of primates have been recorded in the Pacaya-Samiria National Reserve, but four species (brown capuchins, red howler monkeys, saddleback tamarins and common squirrel monkeys) are frequently encountered along the survey transects and are therefore best suited for dissertation projects. Upon locating a troop of one of these target species, the monkeys will be followed for as long as possible, behavioural data can be collected using instantaneous scan sampling and recording troop size, position in the canopy and food preferences. Fruit samples may also be collected to investigate species preference for colour and hardness.

Extended Project Summary

PE65 Behavioural changes during interspecific associations of primate groups in the Peruvian Amazon

Interspecific associations are frequently observed between the various primate species found in Pacaya-Samaria Reserve, and the most frequent of these associations is between capuchin and squirrel monkeys. Living in groups has numerous benefits for individuals, including protection from predation and access to potential mates, but also has costs such as increased competition for food resources. In species which live in groups, such as primates in the Peruvian Amazon, the benefits of group living is assumed to outweigh the costs. Whether and how these costs and benefits change when a group of primates associate with another group of primates of a different species is not well understood. This project looks at how the behaviour of capuchin and/or squirrel monkeys changes, depending on the degree of association with individuals of the other species. Various aspects of monkey behaviour can be investigated, for example, looking at whether time spent being vigilant or feeding, or the type of food consumed changes with distance from individuals of other species. Upon locating a group of either capuchin or squirrel monkeys, the monkeys will be followed for as long as possible, and behavioural data will be collected using focal samples. Additional information, such as distance to the closest individual of another species, and the direction of movement of the whole group will be recorded.

Extended Project Summary