Mammal topics

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

HO11 Variation in cloud forest small mammal populations and their microhabitats, Honduras

A total of 19 small mammal species have been recorded in Cusuco National Park comprising a complex community. However, three focal species are of interest and dominate the community: 1) Desmarest’s spiny pocket mouse (Heteromys desmarestianus) which occurs on the forest floor >150m from the nearest river (terrestrial environment), 2) the Mexican deer mouse (Peromyscus mexicanus) which occurs along river corridors <3m from the water’s edge (riparian environment), and 3) a currently unidentified Rheomys spp. watermouse which is entirely aquatic and forages by diving within upland rocky streams (riverine environment). Therefore, three traplines are set at each of seven camps throughout the park, each consisting of 12 traps placed approx. 10m apart. These traplines are set up in each microhabitat targeting each of the three small mammal species for comparative and individual study. How these species share the forest and the individual specialism of each species remains largely unknown. Small mammal abundance and species composition can be related to habitat data collected from permanent plots along the transect network (for example forest structure, tree density, % fruiting, leaf litter depth etc.). Additionally, abundance and special distribution patterns may be related to predator abundance and distribution (mainly large snake species including Wilson’s pit viper, Cerrophidion wilsoni), building up a picture of the trophic relationships in the region.

Extended Project Summary

HO12 Using camera traps to quantify human disturbance of large mammal species, Honduras

Large mammals, despite their size, are rarely observed in forest habitats and are often under-represented in biodiversity studies. By using indirect survey techniques to increase detectability, a total of 23 large mammal species have been recorded in Cusuco National Park using field signs such as footprints or droppings. These include the endangered Baird’s tapir and species which are commonly hunted for bushmeat such as red brocket deer and white collared peccaries. Camera traps are deployed throughout Cusuco National Park, placed either within 20m of the sample route network or up to 300m away from the sample routes. This enables us to examine the distribution of large mammals throughout the park with respect to distance from the park boundary, human habitation and nearby deforested patches and also distance from our transect network, focusing on the effect of human disturbance. For key target species for which there are >10 detections throughout the season, the Random Encounter Model (REM) may be employed to estimate probable abundance. Data from previous years will be available for comparison enabling temporal trends in detections to be assessed. NOTE: this project involves hiking the entire transect network and also considerable distances off transect. The park has an average slope of 30°. Thus, moderate to high levels of physical fitness are essential for students undertaking this project.

Extended Project Summary

HO13 Ecology and behaviour of bats in tropical cloud forests, Honduras

Cusuco National Park has a fantastic diversity of bats that have adapted to the incredibly complex landscape with huge variation in elevation, temperature and rainfall resulting in a wide range of habitats. Bats in the park have been monitored between June and August each year since 2006 using mist net surveys. Over 50 species of bats have been captured at Cusuco including insectivores, nectarivores, frugivores, carnivores and sanguivores. In addition to abiotic data on lunar phase, precipitation and temperature, habitat measurements are also available. Potential ecology projects include examining the effects of abiotic variables, prey abundance and/or habitat type on bat abundance or demography. Studies could also examine how ecological variables contribute to annual variation in bat abundance or diversity using Opwall’s historical data. The abundance and diversity of bats in Cusuco permits comparisons within or across species or guilds. In addition to mist netting, acoustic surveys using ultrasonic recording equipment are now being implemented. This permits projects on vocal behaviour, such as examining echolocation or social vocalisations in individual species, developing species identification using echolocation signals, or comparing mist net and acoustic survey data for species presence and abundance.

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

ME48 Large mammal abundance and distribution patterns in relation to habitat characteristics and hunting in the Mayan forest

Large mammal density at Calakmul Biosphere Reserve is very high and the forest is one of the last remaining strongholds of endangered mammals such as spider monkeys, jaguar and tapir. Although these species are not hunted, indigenous people are allowed to hunt other large mammals such as peccary and deer (which are the preferred prey of jaguar and puma). The tropical semi-deciduous forest in the Calakmul Biosphere Reserve is unusual in that areas close to the Mayan Ruins contain unusually high densities of large fruiting trees (the result of Ancient Mayan agro-forestry) in comparison to other areas. As there are no rivers or streams in the reserve, forest structure is also heavily affected by distance from the few permanent water sources in the reserve known as aguadas. The aim of the large mammal research project is to investigate the relationship between habitat characteristics and large mammal abundance and ranging, and to investigate the impact of hunting of preferred prey species on the abundance and distribution of felids. Mammal abundance data will be collected along a series of forest transects using distance sampling (based on visual sightings of more commonly encountered species such as primates) and patch occupancy sampling (based on tracks and signs of more elusive species such as tapir and jaguar). Additional data will be collected using camera traps enabling comparison of density estimates produced by the different types of surveys. The survey transects are distributed across a wide range of forest habitat types and each transect contains a number of 20m x 20m habitat survey plots. In each of these plots, tree species will be identified, and DBH and tree height will be measured. Large mammal data from each transect can then be related to mean habitat characteristics for the transect and comparisons between mammal abundance and habitat variables may be investigated.

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, between 2015-2016 the reserve suffered a severe drought and during this time virtually no fruit was available. By 2017 rainfall and fruit production had returned to normal. 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

ME50 Bat abundance, diversity and distribution patterns in relation to habitat characteristics of the Mayan forest

Bat abundance in the Calakmul Biosphere Reserve is very high due to the presence of multiple caves that act as roost sites. There are over 90 bat species that occur in tropical Mexico, but the presence of the majority of these species in Calakmul remains unclear due to lack of standardized studies. Moreover, bat diversity is unlikely to be uniform throughout the reserve due to changes in the habitat resulting from vicinity to ruins sites (Mayan ruins contain unusually high densities of large fruiting trees as a result of Ancient Mayan agro-forestry) and the limited water supply in the reserve. Students will investigate bat abundance and diversity using mist net surveys in conjunction with bat detectors that record bat vocalizations. These combined methods will provide data on the carnivorous, frugivorous and nectivorous bats that are frequently caught in the nets and the insectivorous bats that have such fine-tuned echolocation that they can detect mist nets and are therefore virtually impossible to capture. These data will be collected across a range of transects in the reserve that encompass different habitat characteristics. Each transect contains a number of 20m x 20m habitat survey plots that provide detailed information of the forest characteristics in the area. In each of these plots, tree species will be identified, tree DBH, understorey vegetation, canopy openness, and the number of saplings will be measured. Bat data from each transect can then be related to mean habitat characteristics for the transect and comparisons between bat diversity and habitat variables may be investigated.

Extended Project Summary

PE62 Population trends and habitat preferences of pink and grey river dolphins in the Peruvian Amazon

The pink dolphin Inia geoffrensis and grey dolphin Sotalia fluviatilis are endemic to the Amazon rivers and function as indicator species for the general health of aquatic habitats. Dolphins make an excellent indicator species because they rapidly move out of polluted or degraded habitats and in turn quickly indicate changes in the condition of aquatic systems. Moreover, dolphin abundance directly relates to food supply and thus dolphins can be used to monitor the sustainability of fishing by local communities. The dolphins are also easy to count and observe since they frequently surface, are large-bodied and very distinctive. The river dolphin population in the Pacaya-Samiria has been monitored for several years using fixed-width transects along rivers, lakes and channels via small boats. During these surveys, all dolphin encounters are recorded noting the species, number of individuals, habitat in which the dolphins were seen and the dolphin behaviour. Dissertation topics could examine the health of the aquatic systems in the Peruvian Amazon by evaluating population trends of the two species of river dolphin over time, or could focus on habitat, behaviour and group size differences between the two species. Dissertations could also incorporate the long-term fish monitoring dataset to investigate changes to dolphin abundance over time in relation to changing fish stocks.

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 Pacaya-Samiria flood as the waters rise between December and June, 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 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 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

SA66 Assessing the ranging patterns and habitat use of African elephants in fenced reserves

Despite continental declines, elephant populations in South Africa are among the healthiest in the world. Many small, private game reserves promote high elephant densities as they are a huge draw for tourists. However, the reserves are almost always fenced, which restricts the natural movement of the elephants and can lead to the occurrence of negative human-elephant interactions. To mitigate conflict, it is important for the reserve management to understand these movements and the motivations behind them. Opwall and its partners are working in reserves across South Africa and Swaziland to assess the behavioural impacts of high local elephant densities. GPS location data on the elephants is collected daily and can be used to assess elephant ranging patterns in relation to other herds/individuals, human habitation, water sources or artificial barriers. Students will also collect detailed data on the elephants’ impact on the reserve through vegetation surveys. These surveys are carried out in all major habitat types found within the reserve and the data can be used to assess the elephants’ habitat usage and preference.