Revised Recovery plan for the Carpentarian Rock-rat Zyzomys Palatalis

Helen Puckey, John Woinarski and Colin Trainor
Parks and Wildlife Commission of the Northern Territory, January 2003

3.0 Recovery actions

Action 1.1 Implement fire, cattle and feral predator management strategies that will maintain or increase habitat quality and extent at existing sites

Carpentarian Rock-rats show a clear association with monsoon thickets growing on rocky slopes. Such thickets are vulnerable to hot fires. Management strategies to protect thickets from fires will be developed. These will include annual assessment of fuel loads at thicket margins, fuel reduction burning around thicket edges in the early dry season, and/or fire suppression. Fencing for the exclusion of cattle and trapping for control of feral predators (cats) will be considered for some sites where further research and monitoring highlights the need.

Responsibility: PWCNT, BFC and existing landowner of Wollogorang.

Costs:
Year
1
2
3
4
5
Total
Total
15.8
7.9
7.9
15.3
8.4
55.3

Action 1.2 Establish a formal protected area for known populations

Formal protection measures should be established for at least two known sites. This may include a management agreement with the existing landowner (under Section 74 of the Territory Parks and Wildlife Conservation Act 2000). Any such management agreement should be accompanied by clear guidelines which define management actions and responsibilities aimed at the conservation of Carpentarian Rock-rat. Formal protection measures may also include the declaration of known sites as areas of essential habitat (under section 37 of the Territory Parks and Wildlife Conservation Act 2000).

Responsibility: PWCNT, in association with the existing landowner.

Costs:
Year
1
2
3
4
5
Total
Total
4
2
0
0
0
6

Action 2.1 Continue studies of diet and habitat requirements that will assist in the conservation management of the species

Current and previous studies have described broad patterns of diet for the Carpentarian Rock-rat and closely related species. However, there is little information on within- and between-year variation in food availability, whether Carpentarian Rock-rats depend on surrounding woodland vegetation for food resources, and what factors may be involved in food limitation. This action would investigate diet and food availability, to provide information for habitat management (Action 1) and modelling (Action 3). This should involve consideration of dependency at different times of the year on surrounding vegetation types with changes in diet and food availability; and the identification of further areas of habitat critical to the survival of the species. It may also include consideration of the effects of fire on food availability.

Responsibility: PWCNT.

Costs: included in action 2.2

Action 2.2 Continue studies on population structure and demography

Estimates of total population at known sites are not yet precise, and additional intensive trapping (and mark/recapture) is necessary to determine total population size, and to prioritise actions between known sites. Adequate spatial data are to be collected for the available habitat at each site. The age and sex composition of all known populations should be carefully determined and compared, to examine for signs of declining populations and to provide parameters required for determining age and sex composition of any potential reintroduced population (from captive-bred sources) if necessary in the future.

Responsibility: PWCNT

Costs:
Year
1
2
3
4
5
Total
Total
32.8
27.9
24.1
22.6
0
107.4

Action 3 Establish iterative PVA models that will incorporate new biological information as it becomes available

The long-term persistence of Z. palatalis is threatened by altered fire regimes, grazing by feral animals and stock, weed intrusion, and the stochastic hazards associated with small, fragmented populations. To assess the relative importance of these threats and develop practical management options, a population and habitat simulation model (PVA) has been developed. This will be used to predict the future fate of the species if current conditions perpetuate, determine the relative sensitivity of various demographic and environmental factors for population viability, and help determine the most effective management strategy. As new information becomes available through monitoring, field experiments and laboratory trials, the PVA model will be iteratively updated, leading to a refinement of management strategies and improved precision of its risk estimates.

Responsibility: Key Centre for Tropical Wildlife Management, PWCNT

Costs:
Year
1
2
3
4
5
Total
Total
10
2
1
1
1
15

Action 4 Maintain a viable captive breeding population

A captive-breeding population has been established at the Territory Wildlife Park, consistent with the stated role of this facility in contributing to the conservation of the NT's threatened fauna (A strategy for the conservation of threatened species and ecological communities in the Northern Territory of Australia). This population will be monitored, maintained and studied. A formal management strategy for this captive population will be established (covering pedigrees, optimum population size, research needs and opportunities, and housing requirements as well as systems in place for rapid reproduction and release where necessary).

Responsibility: TWP

Costs:
Year
1
2
3
4
5
Total
Total
15
15
15
15
15
75

Action 5 Investigate aspects of the biology of Carpentarian Rock-rats that can be carried out on captive animals

Biological data obtained from individuals in the captive populations can be useful in the further development of PVA models as well as the management of the species in the wild. Such information may include, breeding biology, longevity, genetics, dietary preferences, some behavioural information and animal husbandry.

Responsibility: TWP

Costs: Included in action 4

Action 6.1 Experimentally release captive bred individuals into a potentially suitable area currently unpopulated by Carpentarian Rock-rats

According to the outcome of the modelling process (action 3), individuals translocated to an area not currently occupied would not significantly reduce the risk of extinction, given the presumed nature of the processes involved in the habitat degradation. For this reason translocations are no longer being considered as a primary management tool. However, the experimental release of captive bred individuals into a new area would be very useful as a research tool, allowing us to experimentally gauge the suitability of presumably suitable patches located in close proximity to currently occupied patches, measure the maximum intrinsic population growth rate at low densities, and assess the effectiveness/feasibility of low-cost methods of population re-establishment and recovery.

Responsibility: PWCNT, TWP.

Costs:
Year
1
2
3
4
5
Total
Total
10.5
5.7
4.3
4.3
0
24.8

Action 6.2 Monitor survival of experimental release individuals

The released individuals should be monitored as part of an experiment for at least three years from the time of release. This will involve immediate radio-tracking of some individuals and PIT tagging (for mark-recapture analysis) of all individuals released. Successive trapping efforts will then be used to determine the survivorship, changes in weight or condition, and reproductive effort of the population.

Responsibility: PWCNT, TWP.

Costs:
Year
1
2
3
4
5
Total
Total
12.2
10.1
7.7
7.3
3.8
41.1

Action 7.1 Operate the Recovery Team

The establishment of a Recovery Team, comprising representatives of the diversity of interested parties, charged with prioritising and scrutinising research and management actions is considered the most acceptable means of implementing recovery plans. The case of the Carpentarian Rock-rat is unusual. Its occurrence is remote from the base of most agencies or NGOs. Its entire known range lies within one pastoral property. PWCNT has been largely responsible for the conservation of this species to date. A small Recovery Team has now been established from a core group of stakeholders who have been consulted throughout the duration of the project thus far. Active consultation with the land holder will continue and expert advice will be sought from Recovery Team representatives from Territory Wildlife Park, Bushfires council of the Northern Territory and the Key Centre for Tropical Wildlife Management. Recovery Team meetings will be held once a year. The operation of the Recovery Team will be administered by PWCNT as the lead agency and team members will meet their own costs to attend meetings.

Responsibility: Recovery Team members, PWCNT

Costs:
Year
1
2
3
4
5
Total
Total
1
1
1
1
1
5

Action 7.2 Produce publications, reports, education and interpretive materials

Interpretive materials on the species and the recovery project should be produced for public utilisation. These might be displayed at Wollogorang Station Homestead and at the Territory Wildlife Park as well as distribution through media releases and educational materials for the PWCNT community education unit. Information and results gained from the actions of the recovery plan should be used to publish reports in a range of media including popular science magazines, refereed journals, internal reports and progress and annual reports to funding agencies

Responsibility: PWCNT, TWP.

Costs:
Year
1
2
3
4
5
Total
Total
5.1
12.6
2.5
2.5
2.5
25.2