Northern hairy-nosed wombats at Epping Forest National Park
General information on Epping Forest National Park
For many years Epping Forest National Park was the only place where northern hairy-nosed wombats could be found. After the decline of the species, a small population was discovered at Epping Forest station in 1937, and the national park was gazetted in 1974. As a national park it can only be visited by scientists, rangers and volunteers, and is not open to the public, to ensure that this critical population of wombats is not disturbed.
Epping Forest National Park is located in inland central Queensland. It is 3160 hectares of open eucalypt woodland, with areas of sandy soils where the wombats dig their burrows. Some of the park's soils are heavy clays, which aren't suitable for burrows.
The Park has a management plan, and also a caretaker program where volunteers help to maintain the park and monitor the wombats.
Why is Epping Forest National Park so important to northern hairy-nosed wombats?
Epping Forest National Park is the location for most of the world's population of northern hairy-nose wombats. The last census in 2013 estimated a population of about 196 northern hairy-nosed wombats there (plus another nine at the Richard Underwood Nature Refuge). Epping Forest National Park held the remaining population following the demise of the species in the rest of its range. It is unclear why it persisted there but it is likely that positive and deliberate management by the Dennis family (who managed the land before it was gazetted as a national park) was a contributing factor.
To help recover this endangered species, the department conducts a number of research and management activities for northern hairy-nosed wombats at Epping Forest National Park.
How is the wombat population estimated at Epping Forest National Park
The wombat population is monitored using a range of techniques, which are:
- collection of wombat hair on sticky tape stretched across burrow entrances, so that DNA can then be extracted from these hairs to produce a census estimate
- trapping of live animals to monitor composition, health and reproductive levels in the population
- visual inspections at burrow entrances to detect the presence of fresh tracks, digging, dung or urine splashes that indicate an ‘active’ burrow
- remote cameras at feed stations and burrows to monitor wombat behaviour and to detect the presence of reproductive females and young wombats.
A) Hair censuses
Hair censuses are used to estimate the number of wombats by placing strips of double-sided sticky-tape across the entrance to burrows. The sticky-tape collects the hairs of passing wombats, and then using the extracted DNA from the hair, individuals can be identified.
In October 2005, the hair census produced a population estimate of 115 wombats. This was a significant increase on the 2002 estimate of 90 wombats. The 2005 estimate consisted of 45% females which is not significantly different from parity.
In 2007, the hair census produced an estimate of 138 wombats, a 20% increase on the 2005 census. The female proportion of the population had increased to 53%. This is a major improvement on the 2001 census when only 33% of the population was female.
In September 2010, the sixth census of the northern hairy-nosed wombat population based on genotyping of remotely-collected hairs was done. Hair tapes were set at 248 burrows over a period of six nights, and from each night 60 hair samples were randomly selected for DNA extraction in the field. These extracts were sent to Adelaide University where genotyping took place. The results of this survey were then subjected to mark-recapture analysis at Monash University producing a population estimate of 163 northern hairy-nosed wombats.
The September 2013 census of the northern hairy-nosed wombat population at Epping Forest National Park produced a population estimate of 196 northern hairy-nosed wombats. The continuing increase in numbers is very encouraging and indicates that the recovery actions underway are working.
The increase in population was expected because there has been evidence of good recruitment since 2005. That evidence included direct observation of juveniles, burrow monitoring and camera monitoring. Additionally, good summer rainfall, which was experienced in 2006, 2007 and 2010 is closely correlated to the breeding rate.
With the nine wombats at Richard Underwood Nature Refuge and the high evidence of breeding at Epping Forest National Park since the 2013 census, it is now estimated there are about 230 northern hairy-nosed wombats on the planet.
Thanks are due to the Wombat Foundation and FAME (Foundation for Australia's Most Endangered Animals) who sponsored the sampling and the analysis in 2007.
Planning is now underway for the 2016 census.
B) Live trapping
Before DNA was used as a census tool, trapping surveys were the main method used to estimate the population size. Live trapping of northern hairy-nosed wombats began in 1985.
In some areas of the park, fences enclose areas of habitat that contain the entrances to burrows, with several gaps, or ‘gates’ left open to allow freedom of movement for the wombats. Trapping involves sealing off all but one or two ‘gates’ and placing cage-tunnel traps at the open ‘gates’. In the middle of each trap is a trip-wire of fishing line, that when triggered by a wombat closes the doors at either end of the trap. When the doors close, a radio-signal is sent to the park headquarters, which allows the research team to quickly respond and ensure that the captured wombat spends the least time possible in the trap.
There were major trapping programs in 1993 and 1999 to estimate the population. The animals were initially tagged with an ear tag. PIT tags are now implanted under the skin between the shoulder blades and tattoo an identification number on their ear.
C) Burrow monitoring
An indirect measure of population is the number of burrows. There were 412 burrows at Epping Forest National Park in March 2015.
Burrow monitoring is undertaken on a regular basis (every 12 months) and provides information on the level of activity and which areas are being used by wombats. During monitoring, burrow entrances are checked for wombat sign, and the activity level of wombats is determined by the presence of fresh foot prints and faeces. Seeing small prints can provide good information on the presence of young animals.
D) Remote cameras
It can be difficult to monitor and photograph the wombats, as they are mainly active at night and spend the days deep in their burrows. Remote cameras are one solution.
A remote camera is a camera with a sensor that is triggered whenever an animal walks past. The remote cameras are placed where wombats are likely to pass by (such as near burrows or feed stations), and are left out to monitor that site 24-hours a day, seven days a week. Remote cameras also have the advantage of taking infrared photos at night, which eliminates the need to use a bright flash that could disturb the wombats. At Epping Forest National Park remote cameras are used for gathering data on wombat behaviour and activity, and for detecting the presence of reproductive females and young wombats.
How is the habitat managed at Epping Forest National Park?
Potential threats to the northern hairy-nose wombats at Epping Forest National Park include uncontrolled fires that can destroy large areas of wombat feeding habitat, food competitors, predators that can kill wombats and weeds that can alter and degrade their habitat. These threats have to be managed to help the wombats survive and their population increase.
Australian ecosystems have been evolving with fire for thousands of years. The presence of fire is important for many species and communities and for others it is detrimental. The management of fire for different ecosystems is very challenging with timing, frequency and intensity of fire being important. Today, natural areas require fire management to retain their biological diversity.
A series of controlled burns have been undertaken during 1997, 1998, 1999, 2004, 2007, 2008, 2013 and 2014 on Epping Forest National Park. Controlled burns were planned in 2000 and 2005 but did not occur because of lack of rain. These burns are mosaic burns undertaken in the summer months following rain to ensure that grass growth quickly occurs. There have been two main types of burns:
- block burns outside wombat habitat to reduce fuel loads and promote vegetation diversity
- patch burns adjacent to wombat burrows to reduce buffel grass biomass and improve grass diversity.
Conditions in September 2008 prompted staff to implement an approved planned burn in a section of the park where the wombats occur. The fire was a success resulting in a mosaic of burned and unburned areas. There was evidence that wombats had been rolling in the ashes and interestingly this same behaviour was reported by a staff member some years ago.
Control of competitors
There are a number of species that can compete with the wombats for food (such as cattle, eastern grey kangaroos, swamp wallabies and rabbits), and their numbers are controlled within Epping Forest National Park. The first fence that was built around the park was to keep cattle out of the area as their trampling can collapse wombat burrows. One-way gates and small enclosures have been installed into the predator-proof fence so that macropods can be released from the park.
In 2002, a predator-proof fence was built around all wombat habitat on Epping Forest National Park after a pack of wild dogs killed at least 10 wombats. This fence has been successful in preventing wild dogs entering wombat habitat. Unlike at Richard Underwood Nature Refuge and the bilby enclosure at Currawinya National Park, which have fences with a ‘floppy top’ to prevent the movement of feral cats, the fence at Epping Forest National Park does not have a ‘floppy top’ so feral cats are still able to get in and out.
The management of weeds within Epping Forest National Park is recorded and planned using the department’s PARKINFO system.
Food and water
Drought can reduce the breeding rate of northern hairy-nosed wombats, so supplementary food and water stations have been installed. There are now 30 water troughs distributed throughout all wombat-occupied habitat on Epping Forest National Park. Remote camera monitoring indicates good use of these by the wombats, with regular visits to drink by female wombats carrying pouch young and by young wombats. Some of the water stations are surrounded by a mesh box so that the water is not available to the larger macropods.
Translocation of northern hairy-nosed wombats to the Richard Underwood Nature Refuge
As there is a significant risk that one natural event such as fire or flood could wipe out the entire species at Epping Forest National Park, a second population of northern hairy-nosed wombats was established at the Richard Underwood Nature Refuge in 2009–2010.
The establishment of a second population of northern hairy-nosed wombats has involved:
- catching wombats at Epping Forest National Park using cage-tunnel traps
- sedating, measuring and tagging caught wombats, and undertaking a health check and assessment to gauge their suitability for translocation
- flying suitable wombats to St. George and driving them to the Richard Underwood Nature Refuge
- releasing and monitoring newly arrived wombats to the Richard Underwood Nature Refuge and managing their habitat.
A history of the research on the wombats at Epping Forest National Park
Field research on the northern hairy-nosed wombats first began at Epping Forest National Park in the 1970s. Staff from Queensland Parks and Wildlife Service monitored burrow activity and distribution in the Park, and found that burrows were restricted to areas of deep sandy soils and estimated the population to contain as few as 20 to 30 wombats.
In the 1980s there was a major trapping study of the wombat population, which found evidence that wombat mortality had decreased since construction of the cattle fence in 1982, estimated that the population had increased to about 70 animals, and provided information on the population’s age-structure and breeding. This was followed by a trapping and radio-tracking study that showed the wombats fed within small home ranges, concentrated in the dry bed of an ancient watercourse and built their burrows along its banks, and that these home ranges increased in winter when food resources were scarcer.
The next trapping studies, in the early 1990s, indicated there had been no increase in the population, which was related to the major drought in central Queensland at the time. Of particular concern, was the trend towards a population dominated by older individuals, many of which were male. By 1999 there were signs of a recovery, indicating that the population was responding to the better rainfall and pasture conditions.
Censusing of the wombat population by genetically analysing wombat hair collected on sticky tape at burrow entrances began in 2000. This technique produces more accurate population estimates than trapping and with much less disturbance to the wombats. This census technique has documented the encouraging increase in the wombat population in the last 10 years and the re-balancing of the sex ratio.