|
Herpetofauna ecology topics
IL210 Influence of habitat structure on herpetofaunal assemblage composition in Sulawesi, Indonesia (Weeks 2 - 8; need to have completed IL001) The general aim of this project will be to examine relationships between forest habitat structure and herpetofauna assemblage composition. As part of the overall research and monitoring project, you will assist the herpetology scientist in the collection of herpetofauna data at approximately 60 sampling sites stratified into areas with differing levels of forest disturbance. The surveys at each site will be completed using five buckets buried in the ground with a fence running over and connecting each bucket. These pitfall traps will be checked daily. Time-constrained diurnal and nocturnal censuses will also be undertaken at each site to complement the trapping programme. These data could be supplemented by taking habitat structural measurements at each site, using standard measurements previously developed and the spatial patterns of assemblage composition and individual species with respect to habitat characteristics determined. This project could focus upon the overall herpetofauna community or specific guilds, such as snakes or litter-dwelling species.
IL211 Life history and morphology responses of forest scincid lizards to forest structure and disturbance in Sulawesi, Indonesia (Weeks 2 - 8; need to have completed IL001) Changes in forest structure brought about by disturbance potentially influence microclimate of the forest floor. This has implications for activity patterns, resources, predation and competition of forest reptiles. In order to persist in such modified environments, species may respond to these influences with changes in growth rates, morphology and life history. This project will assess variation in morphology and life history traits of three common forest scincid lizards: Eutrophis rudis, Sphenomorphus variegatum and Parvoscincus sp. As part of the above overall research and monitoring project, students on this project will assist the herpetology scientist in the collection of herpetofauna data at pitfall sampling sites, measure morphology and life history traits of these species, and examine relationships with habitat structure.
IN212 Demography and influence of hunting on stream-breeding frogs on Buton Island, Indonesia (Weeks 2 - 8; need to have completed IL001) Southeast Sulawesi is home to one of the world’s largest frogs, Limnonectes grunniens (individuals over 900 grams have been recorded!). Unlike most frogs, this large species appears to have very few natural predators (e.g. frog-eating snakes, birds and mammals). The only vertebrate predator potentially capable of eating adult L. grunniens in forests environments on Buton is the Malay Civet. However, in addition to these natural predators, L. grunniens is also hunted for human consumption. Previous research on Buton indicates that large frogs in populations subjected to strong hunting pressure are more wary of people than at more remote sites where hunting pressure is presumed to be lower or non-existent. The aim of this project is to get robust data on the population ecology of this species at disturbed and undisturbed population sites. Monitoring transects have been established along streams supporting populations of Limnonectes grunniens near the research centre of Labundo and the Lapago, Bala and Anoa node camps. Populations will be censused at each site, using mark-recapture techniques. Life history, behavior and microhabitat associations will also be measured. Each site will be sampled on consecutive nights for 5 days, which will then be repeated twice during the season. Spatial and temporal variation in population density, key life history traits, and behavior will be compared between sites and across years. As part of the above study, dissertation students will assist scientists collecting data at each node camp. These data can be used to generate population density estimates and size structures for each site, and relate these to relative human accessibility.
IN213 Population ecology of stream-breeding tree frogs on Buton Island (Weeks 2 - 8; need to have completed IL001) Most of the frog species on Buton are endemic to Sulawesi, some have only recently been discovered, and little is known about their ecology and conservation status. A population monitoring program has been established in order to improve our understanding of population dynamics, long-term population trends, reproductive ecology and the role of potentially threatening processes, such as habitat alteration or changed predation regimes. This project will examine the comparative microhabitat associations, activity patterns and reproductive ecology of tree frogs (Rhacophorus georgii, R. monticola one undescribed species) along several forest streams in and adjacent to the Lambusango Reserve. Information will be collected on spatial and temporal distribution of egg nests and variation in relative abundance of males and females throughout the season. This project will also assist with the collection of annual population monitoring data for these species.
HM214 Susceptibility of the threatened amphibian fauna of the Cusuco cloud forests, Honduras, to chytrid fungus infection (Weeks 2 - 8; need to have completed HM001 and HM003) The single most important reason for the need for effective conservation of the Cusuco National Park is the importance of this cloud forest for amphibians. There are 6 species of amphibians found only in the Cusuco Park comprising two tree frogs (Plectrohyla exquisita & Plectrohyla dasypus), one bromeliad frog (Isthmohyla melacaena), two arboreal salamanders (Bolitoglossa diaphora & Cryptotriton nasalis) and one ground dwelling salamander (Oedipina thomasi). In addition, there are another 10 species that are found in Cusuco but which are endangered under the IUCN categories. Of these, two tree frogs (Duellmanohyla soralia & Bromeliohyla bromeliacea) have their largest remaining populations in Cusuco, two tree frogs (Craugastor coffeus & Ecinimiohyla salvaje) and one salamander (Nototriton barbouri) are known from only one other site other than Cusuco. To add even greater urgency, these small populations are now under threat of infection from amphibian chytrid fungus (Batrachochytrium dendrobatidis), which is causing catastrophic amphibian population declines throughout Mesoamerica. Chytrid fungus appears to have reached the Park at least 15 years ago and has caused significant declines in these isolated mountain top amphibians. However, it is still unclear if all species and life stages are equally susceptible to chytrid and whether environmental factors can affect likelihood of infection. Projects could focus on factors affecting infection rates of chytrid in terms of the susceptibility of different species and different life stages of species (i.e. tadpoles versus adults), or environmental factors such as elevation that are thought to affect the prevalence of chytrid in the environment. Data collection for these projects involve locating tadpoles and adult amphibians, recording the species, GPS location and taking skin swabs for subsequent analysis. All skin swabs will be returned to the DNA lab at the Cusuco base camp, where swabs will be analysed using PCR and gel electrophoresis to detect the presence of chytrid DNA in each sample. In addition, projects could investigate methods of chytrid transmission by testing for chytrid presence in rain water, rivers, fresh water macro-invertebrates or boots worn by researchers.
HM215 Abundance and distribution of threatened amphibian populations in the Cusuco cloud forest, Honduras (Weeks 2 - 8; need to have completed HM001) In addition to chytrid infection, the amphibian populations of Cusuco are threatened by habitat disturbance. If the amphibian populations continue to decline, decisions must be made regarding the value of ex-situ conservation of key species for subsequent release once the threats to the population have been resolved. However, in order to make such decisions, it is imperative that we have reliable estimates of amphibian population dynamics. Thus, data are urgently required on the population sizes and distributions of each of the cloud forest amphibian species and the catchments in which each occur. Data collection for this project involves trekking along sample routes through the forest (to monitor terrestrial species) and river-based surveys (to monitor stream-dwelling species), recording all encounters with amphibians, noting the species, number of individuals, GPS location, length and weight of the individual, and taking numerous photographs of each individual as a non-invasive method of capture-mark-recapture monitoring. These data may then be used to calculate reliable estimates of species abundance and may also be added to existing GIS maps of the park to investigate species distribution patterns. In addition, DNA samples may be collected for each individual for subsequent investigation of gene flow between apparently isolated populations and detection of cryptic species (HM331).
HC216 Population monitoring and ecology of the Hog Island Boa Constrictor in the Cayos Cochinos, Honduras (Weeks 5 - 10) The Hog Island Boa is a dwarfed insular race of Boa constrictor that occurs on only two small islands within the Cayos Cochinos archipelago, Cayo Menor and Cayo Mayor (also known as Cayo Pequeño and Cayo Grande, respectively). The popularity of these snakes in the pet trade, due to their light ‘pink’ colouration, small size and relatively docile temperament, resulted in intensive and uncontrolled harvesting of the populations during the 1980s. Within a decade of collection beginning, the populations had reportedly been so severely depleted that almost all adult boas had been removed from the islands. Since the creation of the Cayos Cochinos Marine Protected Area in 1993, the populations have been provided a much higher level of protection against illegal collection for the pet trade and, in 2004, Operation Wallacea initiated a long-term monitoring programme for the populations. Both the Cayo Menor and Cayo Mayor populations are showing good signs of recovery and high densities of boas can now be found on both islands; however, due to small population size, these boas remain extremely vulnerable to future exploitation. Boas are captured on daily visual encounter surveys (VES) and marked with a passive integrated transponder (PIT) tag. Data are collected on size, sex, external parasite load, head morphology and scale counts. Tissue samples are also taken for DNA analysis. Students can benefit from the long-term nature of this data set to investigate trends in survival, detectability and growth as well as estimating current population size, density and habitat use.
HC217 Behavioural interactions and ecology of a critically endangered spiny tailed iguana (Ctenosaura melanosterna) in the Cayos Cochinos, Honduras (Weeks 5 - 10) Ctenosaura melanosterna is a species of spiny tailed iguana endemic to Honduras. The species is listed as critically endangered on the IUCN Red List, and is found only in the Cayos Cochinos and the Rio Aguan Valley on the mainland. Mainland populations of the C. melanosterna are in serious decline due to hunting pressure, making the Cayos Cochinos an extremely important refuge for this species, although illegal hunting within the area is still problematic. The C. melanosterna population around the research centre on Cayo Menor has been the subject of a long- term study where a large percentage of individuals have been captured and marked with passive integrated transponder (PIT) tags. Individuals are also marked with numbers on their sides for easy visual identification. The study has been ongoing for 5 years and short biographies of many of the animals are known (changes in home range, associations with other animals, etc). Possible studies may include home range and behavioural analyses of specific individuals around the research centre as well as growth and body condition between years. Alternatively, transects and distance sampling could be utilised to attempt to estimate population size within the interior of the forest.
HB218 The ecology and conservation of Anolis lizards in the Cayos Cochinos and Bay Islands, Honduras (Cayos Cochinos: Weeks 5 - 10) This topic centers on the thermal ecology of lizards in the genus Anolis from the Cayos Cochinos and Bay Islands of Honduras. Since the 1960s, temperatures have risen 2.5°C in the Caribbean, and recent evidence has emerged that suggests global warming will affect forest-dwelling lizards that occur in the tropics much more dramatically than it will lizards in other regions of the world. Because three species of forest-dwelling Anolis are endemic to the Bay Islands (two out of the three occur on Utila), it is valuable to understand their thermal biology in order to predict the effects that global warming will have on their survival. Data types that will be collected include: environmental temperature distributions (from copper plated models shaped like lizards), preferred temperatures of individuals, optimal temperatures for sprinting (involving chasing lizards along a race track), upper thermal tolerances, and internal body temperatures. Additional data types include body size, habitat use, and abundance. Data will be used to predict the effects of global warming on lizard communities as temperatures continue to rise in the Caribbean. Lizards will be captured in the field using small nooses attached to fishing poles. Many other potential projects are available studying other elements of Anolis ecology. In 2012 projects can be conducted in the Cayos Cochinos only, however, data collected on Utila, Roatan and Guanaja will also be available to students.
PP219 Amphibian diversity and abundance in Pacaya Samiria, Peru (Weeks 2 - 8; need to have completed PP001) The Pacaya Samiria National Reserve contains a large diversity of amphibians. This diversity, however, is not well understood, and a detailed survey of the amphibian populations in the three principal forest types in Pacaya Samiria (varzea - flooded forest, aquatic floating vegetation, and palm swamps) would provide vital baseline information. Students could utilise transect surveys to sample the amphibian diversity throughout the Reserve. DISTANCE and other catch per unit effort measurements could then be used to assess the amphibian density.
PP220 Niche separation in caiman species, Peru (Weeks 2 – 8; need to have completed PP001) There are three caiman species (Common, Black and Smooth-fronted) found in the Pacaya Samiria National Reserve. This topic could examine the habitat usage and feeding ecology of the three species to identify how they separate their niches. Spotlight surveys could be completed along the edges of the main river and in a series of oxbow lakes within the forest, some of which are still connected to the main river and some of which are totally separated during the dry season. The species, estimated size and habitat usage of each of the caimans observed during these surveys could be recorded. Animals smaller than 2.5m would be captured by noose wherever possible and more detailed measurements (e.g. length, weight, sex, etc.) recorded from these captured animals. Diet of the captured caimans could be examined by flushing out the contents of the stomach, filtering the regurgitated food and classifying the main constituents. The high abundance of these species and the length of the survey season should ensure a good number of data points for this study.
PP221 Habitat selection and breeding success in river turtles in the Pacaya Samiria National Reserve, Peru (Weeks 2 – 8; need to have completed PP001) Before designation of the Pacaya Samiria National Reserve, there was extensive exploitation of the two largest species of river turtles, with a substantial demand for turtle eggs in Iquitos market. Populations of the Yellow-spotted River Turtle (Podocnemis unifilis) and Giant Amazon River Turtle (Podocnemis expansa) at this time were low. However, since effective protection was introduced together with a head start programme where eggs of the two species were removed from their wild nests, replanted at guard stations, hatched and released back into the river, the populations have recovered with high numbers of the Yellow-spotted River Turtle present. Since 1996, on average 73,000 yellow-spotted turtles hatchlings have been released each year with 16,000 Giant Amazon River Turtle hatchlings also released each year. There is a third much smaller unexploited species of turtle - Podocnemis sextuberculata and no Head Start programme has been necessary for this species. The effectiveness of the Head Start programme can be judged from historical records of numbers of nest sites of the two large species and by comparing the changes in ratios between the two larger and the smallest species since the Head Start programme was implemented. Projects could also be developed on the nest sites of the three species to determine the main features determining nest site selection (e.g. height above river level, proximity of vegetation, substrate type, etc.) in the three species. The Yellow-spotted River Turtle can be censused by boat surveys using paddles only - outboard engines affect the numbers of turtles seen. Habitat selection by the Yellow-spotted River Turtle could be studied from replicate boat transects of the river as well as in adjacent lakes and sidewaters to determine the preferred habitat of different size groups of this species.
Unfortunately the specialist academic advisor for this topic is now unable to join the expedition in 2012. Therefore this project is being withdrawn as we cannot guarantee the high level of academic support which we strive to provide.
MI222 Reptile community ecology and behaviour in Madagascar spiny forests (Weeks 1 - 6) The Malagasy reptile fauna has incredibly high levels of endemism, estimated at 94%, but in recent years a great deal of research has dealt with the issues of taxonomy and distribution resulting in many new species discoveries, and the identification of sites with localised endemism. Work on the community ecology and behaviour of reptiles has received much less research attention and it is these issues which students choosing this theme for dissertation work will deal with. The skinks, geckos and iguanids of Ifotaka are the principal focus and dissertations will be examining the communities of these taxa between different habitat types and areas with differing levels of disturbance. The portfolio of methods being used includes drift fences, pitfall traps, tree and ground cover objects and directed searching on transects. A further set of dissertations will focus on the feeding ecology, habitat use and thermoregulation behaviour by iguanids using focal sampling.
MN223 Colour and colour change in the chameleons and leaf-tail geckos of Madagascar (Weeks 1 – 6) This topic focuses on quantifying the colours and colour change abilities of the Oustalet’s chameleon or the three leaf-tail geckos found in the Mahamavo western dry forests. Oustalet’s chameleon is one of the largest known chameleons. Colour and colour change of chameleons is well known worldwide and is yet surprisingly poorly studied. Chameleons can be brightly coloured and still be very cryptic. They often exhibit rapid colour change but it is almost exclusively used for communicating social status to nearby males and females and not for background matching. Little is understood about the colours and colour variation of natural populations of Furcifer oustaleti. This species has a variety of colour morphs that may correlate with gender or sexual receptivity. Each colour morph also has several potential signalling patches. Patterns will be determined through photography and colour will be quantified using reflectance spectrometry. This project should result in a determination of the different colour morphs and the range of colour variation in each and perhaps a determination of signals are used socially. In the leaf-tail geckos pigmentation is used in a strikingly different way. These lizards are preternaturally good at background matching, both in terms of pattern and of matching actual background colours. There are three distinct species of Uroplatus (Uroplatus henkeli, Uroplatus guentheri, and Uroplatus ebanaui) in Mahamavo that occur in sufficient numbers for colour analysis. The focus of this research will be to compare the colours and colour patterns of individuals to actual capture substrates. A secondary focus will be on the ability of each species to change colour in response to various stimuli. This will be accomplished using photography and reflectance spectrometry.
MN224 Population ecology of Nile crocodiles in Madagascar (Weeks 1 - 6) In Madagascar, Nile crocodile Crocodylus niloticus have a stronghold in isolated areas of the west coast including the Mahamavo wetlands. However, crocodiles are threatened by egg collection for crocodile farms and by local people killing large crocodiles perceived to be a threat. For these reasons, crocodiles are currently listed on CITES Appendix II in Madagascar and international trade in crocodile products from Madagascar is banned. Since there is very limited information about the crocodile population in Mahamavo, it would be very valuable to make a robust baseline estimate of population size and to begin a monitoring programme. Students selecting this project will be able to use a speedboat to undertake surveys in the wetlands by day and at night using distance sampling and taking photographs of basking crocodiles. The photos can be used to uniquely identify crocodiles by the scale patterns on the left and right sides of the base of the tail. This permits ‘capture’-‘mark’-‘recapture’ analysis of the crocodile population without the danger associated with handling these animals. It would be possible to compare population size estimates derived form distance sampling and the detection histories of the ‘marked’ animals. Additionally, it will be possible to explore ranging behaviour, territoriality and estimate densities.
MN225 Population ecology of colubrid snakes or chameleons in Madagascar (Weeks 1 - 6) Three of the species of colubrid snakes in Mahamavo, Mimophis mahfalensis, Leioheterodon madagascariensis, and Madagascarophis colubrinus, are very abundant and can be safely handled and uniquely marked by clipping ventral scales. There are also two very abundant chameleon species, Furcifer oustaleti and F. angeli which can be uniquely marked with UV paint. This system would allow a student to go out with the herpetology team to walk routes on lots of occasions and capture snakes or chameleons, record the locations with a GPS and note individual identification numbers. This would allow estimates to be made of population sizes and densities using mark-recapture analysis. The data could also be used to map home ranges for each individual using minimum convex polygons or kernels and hence test whether these species are territorial.
MN226 Microhabitats and niche partitioning in chameleons or skinks in Madagascar (Weeks 1 - 6) The dry forests in Mahamavo support a very diverse reptile assemblage that shares 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. 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.
|
|
.jpg)
.JPG)
