Wombat monitoring data
To assess the threat of mange to wombat populations in Tasmania, DPIPWE has been undertaking surveys around Tasmania to determine:
- Wombat population trends
- Distribution and prevalence of mange in wombats
This information will help identify the factors that influence wombat populations.
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 35 years and on Flinders Island for 25 years.
At regional and statewide scales, wombat numbers have increased over the past 35 years and numbers have been stable or increasing over the past ten years.
However, counts of wombats in the west Tamar area 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.
Wombat and mange distribution
Wombats occur widely in Tasmania in all majpr habitat types from sea level to 1500 m above sea level. Mange-affected wombats occur throughout large parts of Tasmania, particularly on agricultural land. There are currently no confirmed records of mange from remote areas of western Tasmania, nor Maria Island.
Distribution of wombats (blue circles) and sarcoptic mange (red triangles) in Tasmania. Data obtained from the Natural Values Atlas of Tasmania.
Mange prevalence in wombats
Since 2016, DPIPWE, has been undertaking targeted, standardised surveys to assess the prevalence of mange in wombat populations around Tasmania. Night surveys have been conducted at 24 locations in five of Tasmania's eleven climate regions. Mange was recorded at eight locations and in all five regionas surveyed. Mange may have been present at more than eight locations but was not detected because of low prevalence. Overall, average mange prevalence based on direct observations during night surveys was less than 5%. Mange prevalence estimates are likely to vary as more data are gathered because mange prevalence varies in space and time.
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:
Mange prevalence estimates by region based on direct observation and camera surveys at night.
|Region||Number of locations||Survey type||No. of wombats*||% with mange|
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 have found a major difference in mange prevalence estimates 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.
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.