5 resultados para Wildlife monitoring

em University of Queensland eSpace - Australia


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Demonstrating the existence of trends in monitoring data is of increasing practical importance to conservation managers wishing to preserve threatened species or reduce the impact of pest species. However, the ability to do so can be compromised if the species in question has low detectability and the true occupancy level or abundance of the species is thus obscured. Zero-inflated models that explicitly model detectability improve the ability to make sound ecological inference in such situations. In this paper we apply an occupancy model including detectability to data from the initial stages of a fox-monitoring program on the Eyre Peninsula, South Australia. We find that detectability is extremely low (< 18%) and varies according to season and the presence or absence of roadside vegetation. We show that simple methods of using monitoring data to inform management, such as plotting the raw data or performing logistic regression, fail to accurately diagnose either the status of the fox population or its trajectory over time. We use the results of the detectability model to consider how future monitoring could be redesigned to achieve efficiency gains. A wide range of monitoring programs could benefit from similar analyses, as part of an active adaptive approach to improving monitoring and management.

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In the present paper, we have provided an initial assessment of the current and future threats to biodiversity posed by introduced mammals (predators and herbivores) inhabiting the Australian rangelands, exploring trends in populations and options for management. Notably, rabbits have declined in recent years in the wake of rabbit haemorrhagic disease, populations of feral camels have increased dramatically and foxes appear to have moved northwards, thereby threatening native fauna within an expanded range. Following on, we developed a framework for monitoring the impacts of introduced mammals in the Australian rangelands. In doing so, we considered the key issues that needed to be considered in designing a monitoring programme for this purpose and critically evaluated the role of monitoring in pest animal management. Finally we have provided a brief inventory of current best-practice methods of estimating the abundance of introduced mammal populations in the Australian rangelands with some comments on new approaches and their potential applications.

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In wildlife management, the program of monitoring will depend on the management objective. If the objective is damage mitigation, then ideally it is damage that should be monitored. Alternatively, population size (N) can be used as a surrogate for damage, but the relationship between N and damage obviously needs to be known. If the management objective is a sustainable harvest, then the system of monitoring will depend on the harvesting strategy. In general, the harvest strategy in all states has been to offer a quota that is a constant proportion of population size. This strategy has a number of advantages over alternative strategies, including a low risk of over- or underharvest in a stochastic environment, simplicity, robustness to bias in population estimates and allowing harvest policy to be proactive rather than reactive. However, the strategy requires an estimate of absolute population size that needs to be made regularly for a fluctuating population. Trends in population size and in various harvest statistics, while of interest, are secondary. This explains the large research effort in further developing accurate estimation methods for kangaroo populations. Direct monitoring on a large scale is costly. Aerial surveys are conducted annually at best, and precision of population estimates declines with the area over which estimates are made. Management at a fine scale (temporal or spatial) therefore requires other monitoring tools. Indirect monitoring through harvest statistics and habitat models, that include rainfall or a greenness index from satellite imagery, may prove useful.

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Native mammal populations in Southeast Queensland are under threat from habitat loss through land development, dog attacks and motor vehicle accidents. Animals that are not killed from these impacts are sometimes rescued, rehabilitated and later released back into the wild, usually in their area of origin. Although the release of these animals is a relatively common practice, little post release monitoring has been carried out and reported to assess the success of the animals in the wild. This paper discusses the results of three recent studies which have monitored the movements and health of rehabilitated and translocated koalas (Phascolarctos ciniereus) and common brushtail possums (Trichosurus vulpecular): one conducted by Wildcare Australia in 1995- 1996, the other two in collaboration with the University of Queensland. The results indicate that the survival and health of the great majority of the released animals were good and that they were usually able to establish new home ranges during the tracking period. Such findings seem to contradict the results of studies conducted in southern Australia which have monitored the release of translocated possums and gliders, and suggest that there are some key factors which may be critical in determining the success of such releases. These factors include the age of admission and the duration of care, and in particular the selection of the release site. With both koalas and brushtail possums, the release site was found to be critical in determining both the survival and dispersal of the released animals. Consequently, while these studies confirm that the reintroduction of koalas and common brushtail possums may be a viable management strategy, the individual characteristics of the animals themselves and of their release areas must be carefully considered. It is recommended that further research of these key release factors be undertaken and that the work be extended for other species which are commonly released following rehabilitation.