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

Summary

Current Species Status

Carpentarian Rock-rats qualify as Critically Endangered based on the IUCN criteria of B1 (extent of occurrence km2) a (severely fragmented or known to exist at only a single location) and b (continuing decline, observed, inferred or projected, in ... (iii) area, extent and/or quality of habitat) and B2 (area of occupancy estimated to be less than 10km2) a (severely fragmanted or known to exist at only a single location) and b (continuing decline, observed, inferred or projected, in ... (iii) area, extent and/or quality of habitat). Their distribution is restricted to four sites on Wollogorang Station in the Gulf of Carpentaria hinterland near the Northern Territory/Queensland border. The total population size is thought to be low, its habitat requirements are specialised, and the preferred habitat is vulnerable to damage from current fire regimes. Historical distribution of the species is not known.

Habitat Critical to Survival and Limiting Factors

Carpentarian Rock-rats are closely associated with relatively large (>5ha) thickets of monsoon rainforests occurring on scree slopes in rocky gorges. It is unknown to what extent these monsoon rainforest thickets are being degraded by putative threatening processes of fire, cattle, feral cats and weeds. Thickets comprise only a small proportion of the vegetation in this region, and generally occur as small discrete patches. The extent and floristic richness of thickets decreases rapidly to the south and east of the area known to support Carpentarian Rock-rats (due to rapid decline in annual rainfall), and to the north and west (due to lack of sheltered gorges). Lack of data to define more specific habitat requirements and threatening processes will be addressed by the implementation of this revised Recovery Plan.

Overall Objective

To down-list the species to Vulnerable or Conservation Dependent within 10 years of revised Recovery Plan implementation.

Recovery Criteria

The species population remains stable or increases over the 10 years following implementation of the revised Recovery Plan.

Specific Objectives

  1. Develop and implement appropriate management strategies to maintain known populations.
  2. Continue research into ecology and population demography to fill current information gaps.
  3. Continue to adapt established PVA models as new information becomes available.
  4. Maintain a viable captive breeding population.
  5. Investigate aspects of the biology of Carpentarian Rock-rats using captive animals.
  6. Experimentally release captive bred individuals into potentially suitable areas not currently occupied.
  7. Raise the profile of Carpentarian Rock-rats in the community.

Recovery Actions

  • 1.1 Implement fire, cattle and feral predator management strategies that will maintain or increase habitat quality and extent at existing sites.
  • 1.2 Establish a formal protected area for known populations.
  • 2.1 Continue studies of diet and habitat requirements to define areas of habitat critical to the survival of the species.
  • 2.2 Continue studies on population structure and demography.
  • 3 Iteratively develop PVA models that will incorporate new biological information as it becomes available.
  • 4 Maintain a self-supporting breeding colony containing at least 20 individuals at the TWP.
  • 5 Investigate aspects of the biology of Carpentarian Rock-rats that can be carried out on captive animals.
  • 6.1 Design and implement an experiment that introduces captive bred individuals into a suitable area currently unoccupied.
  • 6.2 Monitor survival of experimental release population.
  • 7.1 Operate the Recovery Team
  • 7.2 Produce publications, reports, education and interpretive materials.
Eestimated cost of recovery (in $000/year)
Actions
1.1
1.2
2.1
2.2
3
4
5
6.1
6.2
7.1
7.2
Total
Year 1
15.8
4
-
32.8
10
15.2
-
10.5
12.2
1
5.1
106.6
Year 2
7.9
2
-
27.9
2
15.2
-
5.7
10.1
1
12.6
84.4
Year 3
7.9
0
-
24.1
1
15.2
-
4.3
7.7
1
2.5
63.7
Year 4
15.3
0
-
22.6
1
15.2
-
4.3
7.3
1
2.5
69.2
Year 5
8.4
0
-
0
1
15.2
-
0
3.8
1
2.5
31.9
Total
55.3
6
0
107.4
15
76
0
24.8
41.1
5
25.2
355.8

Biodiversity Benefits

The Carpentarian Rock-rat is dependent upon the maintenance of floristically rich dry thickets of monsoon rainforest. The protection of this species will require management to maintain the extent, integrity and floristic diversity of this vegetation type. Such management will conserve a substantial number of associated threatened and relict plant species, including Tiliacora australiana, Paraceterach reynoldsi, Pteris tripartita, Alectryon tropicus, Thelypteridaceae sp. nov., and Arecaceae sp. nov., as well as restricted plants in the adjacent woodlands such as Cycas brunnea. The maintenance of spring habitats will benefit the undescribed restricted turtle Emydura aff. subglobosa. The maintenance of thickets in rocky gorges will also help to conserve other vertebrates associated with this habitat, including Short-eared Rock-wallaby Petrogale brachyotis, Rock Ringtail Possum Petropseudes dahli and Sandstone Antechinus Pseudantechinus bilarni. Distribution of non-target species will be collected concurrently with that of the target species and a better understanding of the biophysical attributes of the Gulf region will be gained.

Contributers to the Revised Recovery Plan

  • Parks and Wildlife Commission of the Northern Territory
  • Key Centre for Tropical Wildlife Management, Northern Territory University
  • Environment Australia, Endangered Species Program
  • Territory Wildlife Park
  • Threatened Species Network