MA131 Spatial behavioural ecology of the Malagasy giant hognose snake
The Malagasy giant hognose snake (Leioheterodon madagascariensis), is Madagascar’s largest colubrid snake, attaining sizes greater than 1.5m in length. This species has been documented engaging in ritual combat and active nest defence, and a preliminary investigation suggests that the behavioural ecology of L. madagascariensis is more complex than previously thought. For this project all sightings will be recorded using a GPS receiver and all animals encountered will be captured, measured, weighed and microchipped to allow individual identification. Other novel methods may also be employed to investigate the daily habitat usage patterns of each individual. All data collected will be visualised and analysed utilising GIS software.
MA132 Ecology of amphibians in Mahamavo
Amphibians play a vital role in the ecosystems where they are found. Nine species of amphibians are currently known from Mahamavo, some of which occur in relatively high abundances, even during the long dry season. Data for this project will be obtained by surveying rice paddies, ephemeral and permanent ponds and lakes; recording all encounters; noting the species, the number of individuals and the specific details of the immediate habitat where the animals are found. All data collected will be used to create a monitoring system for future studies whereby the species composition at each water body can be monitored.
MA133 Thermal ecology and UVB requirements of chameleons, skinks and geckos
Ultraviolet light (UVB) is an essential requirement for vitamin D synthesis in the skin of lizards, allowing the uptake of dietary calcium which is necessary for proper bone growth and neurological function. There are also thermal demands upon these animals in order for successful vitamin D production. This project aims to investigate i) the thermal and UVB preferences of some of the lizard species at Mahamavo and ii) how these species utilise their habitat to optimise their exposure to the sun, and hence UVB irradiation, while thermoregulating. Data will be collected by surveying routes for lizard species during daylight hours. Once found, UVB intensity, measured using a solarmeter, temperature and other habitat characteristics will be collected along with morphometric measurements of the individual animals.
MA134 Colour variability and the ecological use of colour in the chameleons and geckos of Mahamavo
There are a wide range of endemic lizards in the dry deciduous forests of northwestern Madagascar. Colour is used in fundamentally distinct ways by the different taxonomic groups of lizards found in Mahamavo. Chameleons are depicted in the media as solely using colour change for crypticity, but in reality the main role of colour change here is in communication with other chameleons. There is some interesting colour variability within Angel’s chameleon and Oustalet’s chameleon as well. There are three species of Uroplatus geckos that really do use colour and colour-change to maintain crypticity. One species is a dead-leaf mimic, a second is a twig mimic and the third is a bark mimic. Colour is variable within species and some change colour quite effectively. Phelsuma are a third group of lizards in which there is substantial colour variability within individuals. They respond to changes in lighting and temperature as well as potential threats from predators. Questions regarding variation in colour and how colour-change is being used can be addressed in all three groups of lizards. Colour can be quantified through using standardized photographs or by using a specialised reflectance spectrometer depending on the specific research question being addressed. Analyses of colour can use general linear models to examine variation in hue, saturation and value and look for statistically significant differences or by using principal components analysis to examine and compare entire reflectance spectrums.
MA135 Microhabitats and niche partitioning in chameleons, skinks, geckos or snakes in Madagascar
The dry forests in Mahamavo support a very diverse reptile assemblage which share the same habitat. Competitive exclusion theory suggests that sympatric species must partition their niches for them to persist and the reptiles in this forest provide a great system to investigate how this occurs. In Mahamavo there are two abundant chameleon species, Furcifer oustaleti and Furcifer angeli. It is thought that Oustalet’s chameleon prefers more degraded forest to Angel’s chameleon, but additionally these species may be selecting different microhabitat niches in terms of height above the ground selected for feeding, branch thickness, ambient temperatures or structural complexity of vegetation. A similar situation exists with a pair of closely related skink species Trachylepis elegans and Trachylepis gravenhorstii which are both very abundant in the forest. It appears that T. elegans is more abundant in drier habitats than T. gravenhorstii, but the picture is probably more complicated at the microhabitat scale. There are also three species of leaf-tailed Uroplatus geckos: U. ebenaui, U. henekli and U. guntheri which share the same cryptic adaptations and feeding strategies yet differ markedly in size. With field data collected from a large number of individuals, it would be possible to compare niches and identify factors which separate species’ niches using principal component analysis, linear discriminant models or regression trees.
MA136 Niche separation and the impacts of disturbance on bird communities in the dry forest
Birds are often used as indicator species for overall ecosystem condition, with species from different ecological niches being impacted to varying degrees by habitat disturbance. The avifauna of the Mahamavo forests contains a number of restricted range species, and other species being restricted to particular habitats. Students choosing this subject will undertake timed species counts and mist net surveys to make comparisons between bird communities in different habitat types and between differing levels of human habitat disturbance. Species distribution models using the spatial records for a given species can then be constructed and the percentage of the variability that can be explained by various environmental covariates (e.g. elevation, climate, land cover) determined in order to construct and validate a statistical model of the probability that a given species will be found in a particular landscape unit. These models can then be expressed as a habitat suitability map and the overlap between these species used to determine the level of niche separation. These dissertation subjects will contribute to our understanding of the avian communities of Mahamavo, and in particular to determining the habitat preferences and relative impacts of habitat disturbance on the bird species from different ecological niches and of different levels of conservation priority
MA137 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.
MA138 Species distribution modelling in Madagascar
Distribution models allow a set of spatial records for a given species (from our databases) to be integrated with maps of environmental covariates (e.g. elevation, climate and land cover) in order to construct and validate a statistical model of the probability that a given species will be found in a particular landscape unit. These models can then be expressed as a habitat suitability map. It will be possible for students to join one of the science teams and contribute to collecting field data for lemurs, forest birds, wetland birds, or reptiles and amphibians and then use our entire dataset to make models for a set of species using either general linear modelling (GLM) or Maxent. Outputs from these studies would be very helpful as the maps produced can feed directly into our systematic conservation planning process and inform the management of the Mahamavo region. High quality maps are also excellent communication tools for explaining the significance of the site to decision makers.
MA139 Landscape ecology in Madagascar
By conducting biodiversity surveys we build up a knowledge base concerning patterns in the environment. However, in order to make resilient conservation plans for a dynamic future characterised by land cover change, climate change, human population growth and infrastructure development, we need to be able to understand the processes which are affecting the distribution and density of species within the landscape. It would be possible to join the teams conducting field surveys of lemurs, forest birds or reptiles to contribute to data collection, then return to base camp and use our full database, linked to our spatial data, to infer population processes from patterns of biodiversity. In particular it would be very useful to test to what extent various species in a particular guild are affected by patch size, edge effects, isolation and compactness and therefore predict the likely consequences for biodiversity of habitat fragmentation in future environmental scenarios.
MA140 Community ecology in Madagascar
Which processes (including habitat and ecological interactions) structure communities of forest birds, reptiles and lemurs in Mahamavo? In terms of habitat, there is scope for comparison of primary and secondary dry forest and exploration of the effects of gradients in moisture between relatively moist and highly xeric forests. This might permit the identification of indicator species for particular forest types. A more sophisticated approach would be to use Mantel tests to test a suite of competing hypotheses about the environmental processes which explain pairwise dissimilarity in the community of reptiles/birds/lemurs. Pairs could be studied and differences investigated as a function of distance, difference in environmental variables such as moisture, and difference in habitat configuration. Additionally it would be possible to test whether ecological interactions, especially competition, within a taxonomic group may be structuring the community. This could be achieved by co-occurrence tests or generalised dissimilarity models. For some groups, development of ecological dissimilarity (ED) based monitoring indicators for environmental condition which track communities through ecological space through time would be a very promising direction to investigate. Alternative directions to take might be to make distribution models and then maps of betadiversity or to use numerical classification to make maps of community types. Finally, for individual taxonomic groups such as birds, it is possible to test for nestedness of communities among a set of sites.