Wombat Mange Prevalence Data
Wombat survey data
To assess the threat of mange to wombat populations in Tasmania, DPIPWE has been undertaking surveys around Tasmania to determine:
- Wombat population trends
- Prevalence of mange in wombats
This information will help identify the factors that influence wombat populations.
In 2017 the University of Tasmania, Conservation Volunteers Australia and the Tasmanian Land Conservancy have assisted DPIPWE in collecting and analysing wombat survey data.
A summary of the results of these surveys is given below with links to more detailed reports.
Wombat Population Trends
DPIPWE has been monitoring trends in wombat populations in northern, eastern, central and southern Tasmania for over 30 years.
Wombat numbers have generally increased over the past 32 years and numbers have been stable or increasing over the past ten years
Counts of wombats in the areas west of the Tamar mirror the decreasing trend in wombat counts recorded by the University of Tasmania in the Narawntapu National Park and provide further evidence that the wombat population in this area has substantially reduced.
The monitoring data indicate that the wombat population decrease is localised to the west Tamar area with no evidence to suggest there is a decrease in wombats more broadly in Tasmania. Closer examination of the monitoring data has not revealed other localised areas where wombat numbers have changed, and this will remain a focus of further investigation.
The report below contains a more detailed summary of wombat population monitoring in Tasmania
Mange prevalence in wombats
In 2017, DPIPWE, Conservation Volunteers Australia and the Tasmanian Land Conservancy commenced surveys to assess the prevalence of mange in wombat populations around Tasmania. Mange was recorded at several locations in northern, central and eastern Tasmania. In many locations no mange affected wombats were detected. This is either because mange was not present or because the incidence is so rare that it is difficult to detect.
Based on night time surveys at locations surveyed to date, mange prevalence varied between 0 and 6%, with an average of around 1% (see tables below).
These results for prevalence of mange affected common wombats in Tasmania are consistent with the results from mainland Australia, where the disease is reported as being widespread with generally low rates of prevalence (less than 5%) with occasional localised outbreaks.
The report below contains a more detailed summary of mange prevalence in wombats in Tasmania
Surveys were conducted at Cape Portland to compare mange prevalence assessments between camera surveys and direct observational surveys and between night-time surveys and daytime surveys in 2017 and 2018.
Mange prevalence (%) based on night time observational surveys
|Cradle Mountain National Park||7||267||267||0||0.0|
|wukalina/Mt William National Park||5||70||70||0||0.0|
Mange prevalence (%) based on night time camera surveys
|Lake Mackenzie (Central Plateau)||41||9||9||0||0.0|
|Five Rivers (Central Plateau)||37||104||103||1||1.0|
|Vale of Belvoir (near Cradle Mountain)||24||57||54||3||5.3|
|wukalina/Mt William National Park||30||23||23||0||0.0|
|Northeast - inland||20||31||31||0||0.0|
|Northeast - coastal||14-33||19||19||0||0.0|
Day time versus night time observations
Click image to enlarge - The ratio of healthy wombats to mange affected wombats observed in the night and day varies because healthy wombats typically feed at night. Mange affected wombat numbers remained steady both in the day and at night.
Similar to previous studies conducted in Australia we found a major difference between day time observations and night time observations of wombats.
Healthy wombats typically feed in darkness and are out of their burrows between dusk and dawn. At Musselroe Bay in June 2017 the actual number of mange-affected individual wombats seen during the night and day surveys was similar – 13 at night and 14 during the day. But healthy wombats were not observed out and about during the day. The prevalence of wombats observed with mange in the day time was 73%, considerably higher than the prevalence of 6% recorded at night time when healthy wombats were out of their burrows.
Studies have shown that mange affected wombats have higher energy requirements because they are fighting the disease and struggle to maintain adequate body temperature and condition due to fur loss and infection. Thus mange affected wombats will spend time feeding during the day as well as at night and, as a result, are more likely to be seen during the day than healthy wombats.