Environment and Resource Management

Xstrata reintroduction project

Experimental design

A risk-weighted staged approach is being proposed. It is planned to move up to 12 animals during the winter of 2009 and additional animals in the following year pending the success of the first translocation. However, it is likely that fewer suitable animals will be trapped due to the difficulties in trapping animals.

In determining the numbers of animals to translocate, we considered:

southern hairy nosed wombat
Southern Hairy Nosed Wombat
Photo: DERM

Precedent - translocation of southern hairy-nosed wombats

The southern hairy-nosed wombat is the closest relative of the northern hairy-nosed wombat and a member of the same genus. It is commonly used as an analogue species.

In the 1970s translocations of southern hairy-nosed wombats were undertaken by the South Australia National Parks and Wildlife Service. Ninety one wombats translocated from one property to four different locations over three (3) months:

Date Release site Number of wombats
29/07/1971
11/08/1971		 Site 1
Site 1
Total 		 4 females
5 males 7 females
16 
28/08/1971
07/09/1971
12/10/1971		 Site 2
Site 2
Site 2
Total 		 3 males 1 female
3 males 4 females
11 males 12 females
34 
27/10/1971 Site 3
Total
 11 males 10 females
21 
17/10/1971 Site 4
Total 		 12 males 8 females
20 

The wild to wild translocations were successful. Animals were taken to areas where the species had become locally extinct and limited monitoring showed that at all release sites there were active burrows after several months and at Site 1 where a follow up visit was done 5 months after the release to reveal that 10 wombats were still occupying burrows on the property. There were three deaths reported - "two animals were found lying close to each other and that their bodies were badly mutilated". The inference is that this was a wild dog attack, something that will not occur at Yarran Downs with the predator-proof fence. The third animal was killed by a vehicle on a nearby bitumen highway. This information comes from unpublished reports.

Social behaviour of northern hairy-nosed wombats

There is limited information on northern hairy-nosed wombat behaviour due to their fossorial and nocturnal habits. Wombats are generally solitary animals; however, they live in clusters of burrows that are used by 4-5 wombats. Burrow sharing also occurs and usually involves females rather than male and female (Johnson 1991). Animals therefore live close to each other and feeding ranges overlap. There was also evidence from the trial translocation that wombats prefer to be in the presence of other wombats shown by animals following the trail or scent of other wombats.

It is important to provide sufficient animals to help establish the social structure of the new colony. From an animal welfare perspective, an effective social structure is a positive factor in individual wellbeing.

Population dynamics - why we are not proposing to use more animals.

To establish a new population of a species it is usually necessary to ensure the founder individuals are selected based on relatedness of individuals. The population has been as low as 35 individuals and has therefore been through a genetic bottleneck.

The breeding rate for northern hairy-nosed wombats (measured as the proportion of females breeding in any one year) correlates closely with summer rainfall (Crossman et al. 1994). This averaged 50-75% in the period 1985-89, decreased to only 20% in 1993 during a major drought, and increased slightly to 25% in 1999.

The trial translocation within Epping Forest National Park (Scientific)

Two sub-adult wombats were translocated from the southern section to the northern section of Epping Forest National Park (Scientific). The outcomes from that trial have significantly influenced the design of the reintroduction project. The report of the trial translocation can be found here. NORTHERN HAIRY-NOSED WOMBAT TRANSLOCATION PROJECT JULY 2006 - FEBRUARY 2007

Trapping technique currently used for trapping northern hairy-nosed wombats

wombat trap
Photo: DERM

Permanent trapping fences surround most active wombat burrows. Open gates are built into these fences where runways lead to burrow entrances. Historically traps were set at the gates with most wombat activity. Gates not trapped are temporarily closed during trapping to create a solid barrier around the burrow. Trapping fences are large enough to contain areas of wombat habitat where wombats can feed while trapping is in progress.

Wombats will be trapped in walk-through cages. These are activated when the wombat trips a nylon fishing line strung across the trap 50 mm above the floor. This causes doors at each end of the trap to fall down, trapping the wombat. A transmitter is activated to alert that the trap has been set off and the trap is checked immediately. All traps are checked at dawn to cover transmitter failure and locked open to ensure that no captures can occur during the day.

No feed or water is provided in wombat traps.


Capture and processing of northern hairy-nosed wombats

All non-target species will be immediately released from the traps after a quick health check by the person checking the traps. Only personnel experienced in wildlife handling and assessment will check activated traps.

Trapped wombats will be assessed by the vet as being suitable to receive anaesthetic while still within the trap.

Anaesthesia will be closely monitored and recorded on a field anaesthetic data sheet. Anaesthetic emergency drugs will be on hand and protocols well rehearsed.

All personnel handling wombats will wear sterile disposable gloves.

Anaesthetised wombats will be processed as quickly and as close to the burrow of capture as possible. During processing, the vet will monitor temperature, pulse rate, respiration rate and O2 level at least every 5 minutes.

For identification purposes, all new wombat captures will have:

The following samples may be collected from trapped wombats:

Animals to be translocated will have radio transmitter collars fitted around their necks to a tightness that prevents interference with the animals' normal functions. These collars are secured using bolts that are snipped and filed to ensure smooth edges. The collars will also be fitted with timed release devices designed to allow collars to be released without having to recapture the animal and are programmable to the nearest hour. Collars will be fitted by experienced personnel and will be checked for tightness by the attending veterinarian. These collars have been successfully trialled under previous approved ethics applications but did not include the timed release device. Animals to be translocated will have collars attached during the first round of trapping to provide time for the animals to habituate to having collars on. Previous research (Woolnough et al. 1998) has found that it takes from ten to eighteen days for an animal to habituate to collars and during this period the animal displays reduced activity levels. By attaching collars prior to the animals being taken to Richard Underwood Nature Refuge, it removes one level of stress during the reintroduction of the animal to the release site.

When processing is complete, wombats will be placed in a recovery crate. Typical recovery time in the crate was 20-30 min in 1999 in which time they will have been moved to the translocation site or to the burrow of capture if unsuitable for translocation. Recovering wombats will be monitored by the vet and will meet the following criteria before being released:

If during processing of a wombat other wombats are located within traps, a decision will be made by the veterinarian and the project manager to proceed with processing of the new animals or releasing them from the traps without processing. This decision will be based upon the animal's demeanour, the time of night, the ambient temperature and the stage of processing of the first animal.

During the 2006 trial translocation the times taken to process animals i.e. from the time the animal is caught in the trap to the time the animal has recovered sufficiently from the anaesthetic to be released were 4 hours 50 minutes and 3 hours 20 minutes.

Transportation and release of northern hairy-nosed wombats to Richard Underwood Nature Refuge

All wombats will undergo recovery from anaesthesia in a recovery box that has been shown to be very successful during previous trapping years.

Wombats to be translocated will then be transported by car to the airstrip in the vicinity of Epping Forest National Park, transferred onto a fixed-wing aeroplane and flown to an airstrip in the vicinity of Yarran Downs. A veterinarian will travel with the animals but due to legal restrictions when flying it will not be possible to treat animals. On arrival the wombats will be transferred to a car and taken to the starter burrows at the release site. There will be a team of staff at Yarran Downs to meet the wombats and undertake all activities at the release site.

At all times wombats will be kept within a temperature range of 12 - 28°C. The temperature range is based on burrow temperatures recorded by Jodie McGill, who studied burrow use at EFNP - when the outside burrow temperature >40°C the deep burrow temperature is no hotter than 28°C and when ground temperature is below 0oC the deep burrow temperature is no lower than 12°C. The maximum daily average temperature at Epping during winter is between 21 and 24°C well within the temperature range maintained within a wombat's burrow. The average daily minimum temperature at EFNP during winter is between 6 and 9°C.

The latest the aircraft will depart from the Epping Forest end will be 06:00 and arriving at the Yarran Downs end at 09:00. Therefore the longest time an animal will be confined to a crate (based on the earliest known capture time) will be 14 hours (most animals are caught later in the night resulting in a timeframe of ten hours or less) during which time the temperature will be maintained at between 12 and 28°C.

What is a starter burrow?

starter burrow
Starter Burrow
Photo: DERM

Wombat shelter will be provided in the form of 'starter burrows' drilled into the ground at a depth, width and angle known to be desirable to the animals based on previous research on burrow architecture and the trial burrows used in the trial translocation of 2006 within EFNP. The provision of 'starter burrows' is to create a secure environment from where the animals can dig modify the starter burrow or use as shelter until they dig their own burrows.

Information for the design of the starter burrow was collected from the measurements taken from 4 burrows on site at Epping Forest National Park in June 2006 and information offered by Jodie McGill and Donna Treby, both who have researched northern hairy-nosed wombat burrow design. Starter burrow design includes the following:

One of the artificial burrows was used by a wombat that was not one of the translocated animals that moved into the area subsequently to being used by the translocated animals. Soil and faeces will be collected from the capture burrows and placed within the starter burrows and runs before the animals are released to make the new burrows familiar to the animals.

One of the translocated wombats spent four days in a 'starter burrow' and two days in rudimentary self-excavated burrows indicative of the wombat's ability to cope with a new environment with 'starter burrows'.

Last updated: 27 April 2009

Northern hairy-nosed wombat, Lasiorhinus krefftii

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