Creating new populations
Glencore reintroduction project
The reintroduction of wombats to a new site was a specific objective of the Recovery plan for the northern hairy-nosed wombat Lasiorhinus krefftii 2004–2008. Multiple populations were needed to reduce the risk associated with having a species in a single location.
Glencore, a global mining and commodities company, sponsored the reintroduction project as part of its Community Investment Program which supports initiatives in the areas of health, education, environment, arts and culture, social and community development, and enterprise and job creation. Glencore continues to support the northern hairy-nosed wombat recovery program delivered by the Queensland Government.
Finding the site
After an extensive assessment of sites across Queensland, Yarran Downs was selected as the most suitable site for the establishment of the second colony.
Although many ecological, financial and operational factors influenced site selection, the most important features were the ability to provide enough suitable burrowing habitat and food resources to support a population. Specifically, sites were assessed through:
- satellite imagery
- soil, landform and regional ecosystem mapping
- vegetation assessments
- soil testing.
The selected site, located on Yarran Downs Station, owned by the Ed and Gabrielle Underwood, near St George, was gazetted as Richard Underwood Nature Refuge on the 27 November 2008 and protects about 130 hectares of eucalypt woodland on old river levees.
On 13 April 2011, a special event was held at Richard Underwood Nature Refuge to celebrate the successful partnership between the department, Glencore, and the Underwood family.
Reintroducing the species back into their former distributions required considerable planning. To maximise the chance of success for the new population a detailed strategy was developed that considered a multitude of factors, including:
- number of individuals
- gender ratios
- health requirements
- where animals will be sourced from
- population capacity of new site
- how animals will be transported
- understanding on genetic representation required in the new population.
The ability to successfully reintroduce wombats into their former distribution was proven in the 1970s when 91 southern hairy-nosed wombats were successfully reintroduced across four sites in South Australia. Due to the close similarities between the species, it was deemed likely that similar success could be achieved in the northern hairy-nosed wombat.
This was tested in 2006, when a trial translocation was undertaken on Epping Forest National Park (Scientific). Two female sub-adult northern hairy-nosed wombats were relocated from the southern section of the park to the northern section. An important technique utilised during the trial was the construction of artificial starter burrows, which provided wombats with immediate shelter when released at the new sites.
To establish a new population, it is necessary to ensure the founder individuals are selected to represent the widest possible genetic diversity. The low genetic diversity in the wombat population at the Park, caused by the bottleneck in the early 1980s, meant it was not necessary to translocate a large number of wombats. However, as northern hairy-nosed wombats are known to co-inhabit multiple burrows with other wombats, it was deemed important that sufficient animals be reintroduced to establish a stable social structure. The Queensland Government commissioned a study by the Australian National University to analyse how the reintroduction of different numbers of individuals may impact the populations’ long-term viability. This study found a cohort of 12 individuals was the most likely to succeed in establishing a long-term population. In addition, it identified the importance of post-release monitoring to determine if additional translocations were required.
Following these recommendations, a risk-weighted staged approach was followed, with plans to translocate up to four male and eight female northern hairy-nosed wombats in the first year, with the potential to translocate additional animals in the following year, based upon the success of the initial reintroduction.
Considerable work was required to make the site suitable for northern hairy-nosed wombats including:
- constructing a house and workshop to support departmental staff and caretakers in managing the site and the wombat population. The house was built from sustainable materials including compressed straw ceiling panels, rice and wheat straw insulation, natural polymers, and hardboard sheeting made from waste forest products
- constructing a predator-proof fence to prevent the entry of wild dogs, feral cats and foxes. After the initial work done by the Underwood family, the fence was constructed by Conservation Volunteers Australia and other volunteers. During the construction of the fence, all predators were removed from the enclosure
- installing supplementary water stations that are filled by a gravity-fed water-reticulation system
- installing wombat monitoring equipment, such as remote cameras and tracking systems
- constructing wombat starter burrows.
What is a starter burrow?
Constructing a burrow requires an enormous amount of energy and time, which could potentially reduce the chance of survival of newly released wombats. To ease the transition and provide wombats with immediate shelter, ‘starter burrows’ were excavated at Richard Underwood Nature Refuge.
Starter burrows were drilled into the ground at a depth, width and angle known to be desirable to the wombats, based on previous research on burrow architecture. Starter burrow design included:
- angle of 30%, to provide easy access for wombats and tunnel stability
- diameter of 450mm (during the translocation it was identified that 350mm was large enough for started burrows)
- the maximum possible depth and length, to help provide stable environmental conditions
- “L shaped” design, to minimise the amount of light reaching the end.
To provide wombats with familiar smells in the area, soil and faeces were collected from each wombat’s capture burrow at Epping Forest National Park (Scientific) and placed within the starter burrows at Richard Underwood Nature Refuge prior to wombats being released.
Translocating the wombats
Translocation involves moving a group of animals to a new area. Translocating wombats from Epping Forest National Park (Scientific) to the Richard Underwood Nature Refuge involved coordination between specialised teams at each site.
At the Park, trapping during early 2009 resulted in the capture of 17 males and four female northern hairy-nosed wombats. Once caught, wombats were sedated, measured, tagged, given a health check, and assessed for translocation. Wombats were deemed suitable for translocation if they did not have pouch young, appeared in good condition (body score ≥3.5) and were greater than 25kg in body weight. These wombats were fitted with radio tracking collars and released back into their burrows at the Park to allow them time to become accustomed to the collar.
Radio collars allowed each wombat’s movement to be tracked so it could be re-trapped for translocation. In addition, infra-red monitoring cameras were set up to monitor the health of collared wombats.
In April 2009, one of the wombats trapped was M23, that's the 23rd male ever trapped. Using his ear tattoo and microchip researchers were able to identify him from previous trapping programs. He was at least 26 years old and the oldest known wild wombat at that time. Given his age, it was decided that he wasn't suitable for translocation and was released back at Epping Forest National Park (Scientific).
During trapping in May 2009, a female wombat (F168) with a pouch young was captured. Pouch young is the name given to joeys during the 8-9 months they spend in their mother’s pouch. Trapping females with pouch young is rare, with F168 being only the fifth recorded since the Park was established, 35 years prior. The pouch young was furless, beginning to grow whiskers around its muzzle and had recently developed two top incisors (teeth). Although estimated at only about 12 weeks old, the wombat’s pouch was already clearly visible, identifying the joey
During the trapping in July 2009, four of the previously radio-collared wombats were recaptured and translocated to Richard Underwood Nature Refuge. In addition, a new, suitable male was also captured, collared and translocated to the Refuge.
Wombats were flown approximately 800km south to St. George, and then driven the remaining 60km to Richard Underwood Nature Refuge.
Initial trap date
|Wombat ID||Age||Weight (kg)||Body condition (out of 5)||Radio tracking collar fitted||Date translocated to RUNR|
|21/04/2009||M23||Adult >26 yrs||31||3||No||Not translocated|
|23/05/2009||F168||Adult with PY||31||3.5||No||Not translocated|
|23/07/2019||M6||Adult >26 yrs.||32||3.0||No||Not translocated|
Release of northern hairy-nosed wombats to Richard Underwood Nature Refuge
A plastic barrel is used to plug the burrow entrance after the wombat’s release down the burrow. Photo: Queensland Government
Prior to being released down the starter burrow, a final assessment of each wombat’s condition is made. To ensure the wombat remains in the starter burrow during the daytime a barrel is used to plug the burrow entrance, which is then removed at dusk. Temporarily holding the wombat within the burrow eliminates the risk of the wombat leaving the burrow before fully recovering from the anaesthetic and allows time for the wombat to settle before venturing out.
Over the nine months following their release, managers periodically used telemetry equipment to radio track the wombats. Radio tracking was done predominantly at night, when wombats are most active, however, regular daytime locations, when wombats were resting in burrows, were also recorded to determine individual burrow use.
Enlarging the population at Richard Underwood Nature Refuge
In 2010, to further grow the population at Richard Underwood Nature Refuge, two more male wombats and seven more female wombats were translocated from Epping Forest National Park.
See our wombat project news for more details about how the northern hairy-nosed wombats are doing at the Richard Underwood Nature Refuge.
|Initial trap date||Wombat ID||Age||Weight (kg)||Body condition (out of 5)||Radio tracking collar fitted||Date translocated to RUNR|
|23/04/2010||F157||Adult with PY||31||4.5||No||Not translocated|