Year

2022

Degree Name

Master of Research

Department

School of Earth, Atmospheric and Life Sciences

Abstract

Diseases affecting wildlife are an increasing concern for the conservation of Australian mammals. Sarcoptic mange (SM) is a highly infectious disease caused by the mite Sarcoptes scabiei. Of all the Australian mammal species affected by SM, the bare-nosed wombat (Vombatus ursinus) has experienced the most severe symptoms and associated population declines. The bare-nose wombats suffer from the most severe form of SM, which is characterised by the extensive thickening and crusting of the skin. Bare-nosed wombat burrows are an essential resource used by various species and acts as an environment reservoir for S. scabiei, due to the stable microclimate burrows provide. Environmental transmission occurs through the exposure of S. scabiei when using bare-nosed wombat burrows that have been deposited by an SM affected individuals that used the burrow prior. This study aimed to investigate the potential transmission pathways of S.scabiei within bare-nosed wombat populations in and around Bundanoon, a town in the Southern Highlands region of New South Wales, Australia. Therefore, the hypotheses were as followed: 1) the diel activity pattern of SM affected and not affected bare-nosed wombats will differ, 2) the diel activity of other host species that interact with wombat burrows will differ to bare-nosed wombat and, 3) there will be distinct transmission pathways identified through burrow-sharing by unaffected and SM affected bare-nosed wombats. Fifteen camera traps were positioned at the entrance of bare-nosed wombat burrows to investigate the interaction and use of wombat burrows by unaffected and SM affected bare-nosed wombats, as well as other host species. Sampling was conducted over a 14-month period during 2021/2022. Kernel density estimates were used to compare the overlap of diel activity between bare-nosed wombats and various species interacting with their burrows. The social network analysis was used to quantify and visualise the indirect transmission pathways of unaffected and SM affected bare-nosed wombats, through the sharing of burrows at different times. In this study, a range of species were observed to interact with wombat burrows and included bare-nosed wombats, red foxes, European rabbits, small mammals (<500g), eastern grey kangaroos, swamp wallabies, short-beaked echidnas, brushtail possums, domestic dogs and cats, and various birds. This study found that indirect transmission of S.scabiei was occurring through both interspecific and intraspecific (cross-host transmission) sources. Overall, this study demonstrates the practical use of diel overlap and social network analysis in the investigation of indirect pathways of S.scabiei transmission in bare-nosed wombat populations in wild settings. The findings of this study can be used to inform wildlife carers and policymakers when constructing control management and treatment regimes. Additionally, the concepts and analyses used in this thesis can be implemented in other bare-nosed wombat populations or host species affected by a wildlife disease.

FoR codes (2008)

0602 ECOLOGY

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Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily represent the views of the University of Wollongong.