DPIPWE has been assessing the number of wombats affected by mange (prevalence) at different locations around Tasmania. This will assist to:
- better understand the threat of the disease to wombats; and
- identify the factors that cause some wombats to be affected and not others.
DPIPWE has also provided funding to Conservation Volunteers Australia to undertake surveys of mange prevalence at several locations around Tasmania.
Mange prevalence is assessed using two primary methods:
- direct observation of wombats at night and day (with the aid of binoculars or spotting scope, as well as a spotlight at night); and
- analysis of images captured by motion activated cameras.
Presented below are results of 2017 mange prevalence surveys conducted to date. Results of further surveys will be added as data become available.
Surveys have been conducted at a number of locations in 2017 as outlined in the tables below.
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 the number of wombats observed.
Mange was detected at Musselroe Bay (northeast Tasmania) and on the Forestier Peninsula (southeast Tasmania) at a prevalence of less than 10% of the wombats observed. At Narawntapu National Park, where there has been a large decline in the number of wombats, two out of the 5 wombats seen showed signs of mange.
Day time versus night time observations
Click image to enlarge - The ratio of healthy wombats to mange affected wombats varies during day and night observations because healthy wombats typically feed at night. Mange affected wombat numbers remained steady during both day and night observations.
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 70%,considerably higher than the prevalence of 8% 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.
2017 Survey Data
Recent night-time observation surveys (with aid of spotlight and binoculars/spotting scope)
|Musselroe Bay||June 2017||170||157||13|
|Musselroe Bay (Survey covered less than half the area surveyed in June 2017)||July 2017||86||84||2|
|Mt WIlliam/wukalina National Park||June 2017||43||43||0|
|Rushy Lagoon||June 2017||18||18||0|
|Cradle Mountain National Park||June 2017||32||32||0|
|Cradle Mountain National Park||July 2017||32||32||0|
|Forestier Peninsular||July 2017||113||112||1|
Day-time observation surveys
|Musselroe Bay||June 2017||20||6||14|
|Musselroe Bay (Survey covered less than half the area surveyed in June 2017)||July 2017||2||0||2|
|Forestier Peninsular||July 2017||63||63||0|
|Narawntapu National Park||June 2017||5||3||2|
DPIPWE Camera surveys
|Mt William/wukalina National Park||February-March 2017||23||23||0|
|East coast||January-June 2017||6||6||0|
|North coast||January-June 2017||7||7||0|
|Northeast coast||January-June 2017||12||12||0|
|Lake Mackenzie||February-March 2017||9||9||0|
Comparison of mange prevalence between night and day observations at Musselroe Bay
|July 2017 (Survey covered less than half the area surveyed in June 2017)||Night||86||84||2||2%|
|July 2017 (Survey covered less than half the area surveyed in June 2017)||Day||2||0||2||100%|
Wombat Population Trends
DPIPWE has been monitoring trends in wombat numbers 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 eight 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 been 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 have not revealed other localised areas where wombat numbers have changed, but this will be the focus of further investigation.
The report below contains a more detailed summary of wombat population monitoring in Tasmania