Office for Environmental Programs - Theses

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    A community based management plan for kangaroos in Anglesea, Victoria
    Inwood, Danielle ( 2006)
    No abstract available
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    Design for persistence: graph-based connectivity, habitat reserves and species persistence
    Mullerworth, Daniel ( 2007)
    Connectivity is widely thought to play a key role in the persistence of metapopulations. However, there is no generally accepted approach to measuring connectivity in landscapes. Current reserve selection algorithms tend to focus on clustering habitat sites as an approach to maximising connectivity. An alternative approach to understanding connectivity is, however, to focus on the spatial configuration of habitat patches in a landscape. In this study, graph methods are used to represent habitat networks and investigate the relationship between spatial configuration and the flow of species moving across the network. Betweenness Centrality, a graph metric designed to measure the proportion of traffic passing through any node in a network, is applied in modified form as a reserve selection algorithm. The performance of reserves selected using Betweenness Centrality is assessed against species persistence measures from the metapopulation model RAMAS and compared to equivalent reserve selections for other well known reserve selection algorithms. Within the limited set of cases considered, this study found that Betweenness Centrality has a high degree of success in designing reserves for species with high dispersal characteristics, but is unable to predict appropriate reserve sites for low or non-dispersing species. Further directions for research in the field are suggested, with an emphasis on rigorously validating this type of approach to understanding connectivity.
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    A population viability analysis (PVA) for Eastern Sarus Crane, Grus antigone sharpii
    Nguyen, Hoa ( 2005)
    The Sarus Crane Grus antigone (Linnaeus, 1758), a wetland bird species in South East Asia and Northern Australia, is currently listed as a globally vulnerable species. A subspecies of this bird, the Eastern Sarus Crane G. a. sharpii is distributed in the lower Mekong basin, South East Asia and is considered endangered due to its small population size, about 500-1000 individuals, inappropriate reserve management, and the intense development pressures in the region. A population viability analysis (PVA) of the birds may help managers to comprehend the processes governing the population dynamics and then highlight needs for future conservation, management, and research activities. Part 1 of this paper provides requisite data for the Eastern Sarus Cranes' PVA, including estimates of population abundance, survival and fecundity rates, and the carrying capacity of the area supporting the population. These data were obtained from fieldwork between the years 2001 and 2004 by the author and from a review of the literature. Part 2 is the description and simulations of the PVA models. Three stage-based demographic models of the population were run in RAMAS/Metapop 4.0 (Akcakaya 2002) to understand structural sensitivities of the models. Different scenarios were then run on the complete model to investigate the effects that each of them has on the model outcomes. The compiled data were also parameterised and simulated in VORTEX 9.5 (Lacy et al. 2005) to compare the risk estimates made by the two modelling packages. Part 3 involves discussions and conclusions of the results from the PVA models and proposals of management and conservation actions for the population. Although habitat loss has been considered the most threatening process to the population, the models were particularly sensitive to changes of poaching activities on the population. It is therefore suggested that improved population management is the most cost-effective option for the conservation of the endangered subspecies in the near future.
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    Distribution and abundance of five threatened marsupials at Mount Rothwell
    Poole, Eliza ( 2005)
    The conservation and management of Australia's threatened marsupials must be based on a sound knowledge of their biology and ecology. Two aspects of ecology, distribution and abundance, are of particular importance. This study examined the distribution and abundance of five species reintroduced at Mt Rothwell. A brief examination was also made of each species' sex ratio and general condition. Data was collected via a markrecapture survey, and analysed using the MARK computer program and Arcview mapping software. An estimated 164 +-28 Rufous Bettong (Aepyprymnus rufescens) inhabit Mt Rothwell and were trapped predominantly in grassland habitat. Although the population size of Eastern Quoll (Dasyurus viverrinus) could not be reliably estimated, it is assumed to consist of 20 individuals, almost all found in the grasslands. Southern Brown Bandicoot (Isoodon obesulus) were the most populous species, with 289 +- 82 individuals inhabiting both woodland and grassland habitats. There was insufficient data to estimate the population size of the Eastern Barred Bandicoot (Perameles gunnii), but fourteen individuals were released one year ago, and all trapped individuals were in the grasslands. Conversely, Long-nosed Potoroo (Potorous tridactylus), estimated at 30 +- 12 individuals, were found exclusively in woodland habitat. The results of this study will provide baseline information necessary for future management decisions, and will be of great benefit to the conservation of these species at Mt Rothwell.
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    The effects of coupe level timber harvesting on the home range dynamics of the swamp wallaby (Wallabia bicolor) in the Pyrenees State Forest, Victoria
    Greenfield, Andrew ( 2005)
    The effects of coupe-level timber harvesting on the swamp wallaby was investigated using home range dynamics and habitat selection as an indicator of the extent of the impact. An MBACI design incorporating five control sites and one impact site was used as control for background variation. The results indicate that there were significant changes in the home range size, home range overlap and the geographic centre of location. However, there was no significant change in the centre of activity. Harvesting only appeared to affect animals that had their home range directly on the coupe. The affected animals showed two responses to harvesting. They either increased their home range size or moved away from the coupe altogether. Those animals that did not use the coupe showed little change in home range dynamics. In selecting habitats, the wallabies showed a preference for old burnt forest and forest habitat rather than the harvested area and new burnt forest created by the timber harvesting.