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Disturbance ecology of the greater bilby (Macrotis lagotis)

Dawson, StuartORCID: 0000-0003-4432-3779 (2017) Disturbance ecology of the greater bilby (Macrotis lagotis). PhD thesis, Murdoch University.

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Understanding how species respond to disturbance, both natural and anthropogenic, can be crucial to designing effective and targeted management strategies. The greater bilby is a medium-sized Australian marsupial that has suffered a dramatic decline in distribution since European settlement, largely due to introduced predators (foxes and feral cats), agriculture, and changed fire regimes. I conducted a series of natural experiments to investigate the habitat selection, predator-prey interactions, and ecosystem engineering of the bilby in the grazed rangelands of the West Kimberley; I also explored the impacts of fire and clearing of seismic lines (for petroleum exploration) on these processes. Firstly, I used remotely sensed and field sourced habitat characteristics, selected based on previous studies, to identify and predict the presence of bilbies. All variables used had little power to explain the presence of bilbies. Secondly, I investigated the effect of disturbance at two scales; at a fine scale, by investigating the use of seismic lines by a range of species, and at a broad scale, by recording changes in the occupancy of a range of species within disturbed area. I found that seismic lines are used by bilbies, cats, and dingoes (a naturalised predator), increasing the spatial and temporal overlap between bilbies and potential predators. The diet of a species is an important ‘bottom-up’ regulator, often influencing the habitat preference of a species. Therefore, thirdly, I tested the efficacy of contemporary methodologies for identifying bilby diet, determining that DNA barcoding can improve identification of dietary items from scats. Lastly, I identified a diverse range of species that use bilby burrows for shelter, indicating that bilbies are important ecosystem engineers. My research faced significant challenges associated with the rare and cryptic nature of bilbies and their predators, especially feral cats, and I provide suggestions for useful and practical approaches for future research. Anthropogenic disturbance can influence predator-prey interactions, which may increase the predation pressure on an already vulnerable species, adding to existing management concerns for bilbies in the West Kimberley associated with vegetation clearing, unmanaged and frequent broad-scale fires, and cattle grazing. Land managers should work in concert to reduce pressures on bilbies, by using of coordinated and targeted cat control, and managing fires to increase fire-age heterogeneity.

Item Type: Thesis (PhD)
Murdoch Affiliation(s): School of Veterinary and Life Sciences
Supervisor(s): Kobryn, Halina, Bateman, Bill, Adams, Peter, Waddington, Kris, Moseby, Katherine and Fleming, Trish
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