Zyzomys pedunculatus 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Mammalia Rodentia Muridae

Scientific Name: Zyzomys pedunculatus (Waite, 1896)
Common Name(s):
English Central Rock-rat, Macdonnell Range Rock-rat
French Rat à grosse queue
Spanish Rata Coligorda

Assessment Information [top]

Red List Category & Criteria: Critically Endangered A2abce ver 3.1
Year Published: 2016
Date Assessed: 2015-07-20
Assessor(s): Woinarski, J. & Burbidge, A.A.
Reviewer(s): Amori, G.
Contributor(s): Edwards, G., Morris, K. & Ward, S.
The Central Rock-rat has exhibited a very marked decline in range and abundance since European settlement of Australia. It is now known from very few sites (all in the Wes MacDonnell Ranges of central Australia) despite substantial survey effort (McDonald et al. 2013, 2015a, 2015b; Woinarski et al. 2014). It has shown a marked decline since 1999 (of  > 80%) at the only long-term monitoring site (Edwards et al. 2013a, Dickman et al. 2014), so is considered Critically Endangered A2abce. Major threats are presumed to be predation by introduced predators (feral cat and Red Fox), and inappropriate fire regime, leading to habitat degradation. It probably qualifies at least as Endangered due to small and declining population size and small area of occupancy, but these parameters are not well resolved.
Previously published Red List assessments:

Geographic Range [top]

Range Description:This species is endemic to Australia, where it is known only from a small number of disjunct localities in the West MacDonnell Ranges, Northern Territory (Cole 2000), with a recent discovery at the isolated Mt Edward (c. 70 km west of the nearest known location in the West MacDonnell Ranges) (McDonald et al. 2015a). The species has previously been recorded from living animals or cave deposits in Northern Territory at Uluru-Kata Tjuta National Park, Illamurta (James Range), Haast's Bluff (West MacDonnell Ranges), Mount Liebig, Napperby Station, Devils Marbles, The Granites (Tanami Desert), and the Davenport Range. It is known from cave deposits in the Cape Range, Western Australia (Woinarski et al. 2014).
Countries occurrence:
Australia (Northern Territory)
Additional data:
Estimated area of occupancy (AOO) - km2:20Continuing decline in area of occupancy (AOO):Yes
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:1000
Continuing decline in extent of occurrence (EOO):YesExtreme fluctuations in extent of occurrence (EOO):No
Number of Locations:1Continuing decline in number of locations:No
Extreme fluctuations in the number of locations:No
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:The population size and abundance of this species is not well known. The species was thought to be extinct (no records between 1960 and 1996), and was subsequently rediscovered in fourteen sites in 1996-2001, with subsequent disappearance from most of these sites (e.g. Nano 2008; Edwards 2013a; Dickman et al. 2014). Records since 2001 are restricted to a few sites, and the size of these subpopulations is unknown but probably very small (McDonald et al. 2013, 2015a 2015b; Woinarski et al. 2014). Woinarski et al. (2014) considered that the population size was <1,000 mature individuals, albeit with low reliability.
Current Population Trend:Decreasing
Additional data:
Number of mature individuals:800Continuing decline of mature individuals:Yes
Extreme fluctuations:NoPopulation severely fragmented:Yes
No. of subpopulations:10Continuing decline in subpopulations:Yes
Extreme fluctuations in subpopulations:NoAll individuals in one subpopulation:No

Habitat and Ecology [top]

Habitat and Ecology:The Central Rock-rat is a nocturnal terrestrial rodent. Its diet comprises mainly seeds, but it also includes some plant stem material and a low proportion of invertebrates (Nano et al. 2003, Edwards 2013b). In drier conditions, the proportion of seed in the diet declined and that of plant stem material increased (Edwards 2013b). Plants contributing most to the diet included Sida spp., Solanum spp., and Triodia brizoides; and most plant species reported in the diet are considered common, widespread and fire-tolerant (Edwards 2013b).

The core habitat of the species during the contracted phase of the population cycle is quartzite ridge tops and cliffs supporting spinifex Triodia spp. grasslands or shrublands, perhaps with scattered trees. In the break-out phases they can be found in a much wider range of rugged rocky landforms and habitats, including scree slopes, hills and valley floors, on granites, limestone, quartzite and sandstone (Wurst 1995) supporting a range of vegetation types, including tussock and hummock grasslands, low shrublands and low open woodlands (Woinarski et al. 2007). Most sites have a stony ground cover (Cole 1999). Cole and Woinarski (2000) considered that it preferred relatively long-unburnt vegetation supporting fruit-producing plants, but Nano et al. (2003) and Pavey (2002) noted instead a specialised diet of seeds, including from plant species that are ‘fire-encouraged’, and considered it unlikely to be a habitat specialist. It is likely that fire-protected areas with relatively high moisture availability may be critical refuge areas during low rainfall periods, with the species expanding its habitat range in wetter periods. The known population declined severely following a period of low rainfall and extensive fire in 2002, with decline occurring in both burnt and unburnt areas (Edwards 2013a; G. Edwards pers. comm.). Like other Australian desert mammals, the Central Rock-rat may be a boom-bust species, likely to be disadvantaged by combined impacts of fire and feral predators superimposed on, and linked to, decadal-scale climatic variation (Letnic et al. 2005).

Little is known of reproduction seasonality or success. Captive females have given birth to 1-4 young (Cole 1999, Nano 2008). In the wild, juvenile individuals have been reported in March, April, July and November, indicating that, in suitable conditions, breeding may occur throughout the year (Edwards 2013a).  Generation length assumed to be 1-2 years, based on information on age at sexual maturity (5-6 months: Begg 1981) and longevity (probably 2-3 years) for congeneric species.
Continuing decline in area, extent and/or quality of habitat:Yes
Generation Length (years):2
Movement patterns:Not a Migrant

Threats [top]

Major Threat(s): Threats are not well resolved. Recent evidence has shown predation by feral cats (McDonald et al. 2013). Other threats may include predation by dogs or foxes; inappropriate fire regimes; and habitat degradation due to weeds (Woinarski et al. 2014).

Conservation Actions [top]

Conservation Actions: Most or the remaining known occurrences are within conservation reserves. The species is listed as threatened under Australian legislation and on Appendix I of CITES. Nonetheless, the species is probably undergoing ongoing decline because threats are not effectively managed. More information is required on distribution, population size and threats. Formerly-held captive breeding populations have now been abandoned. Intensive threat management and reintroductions will be needed for conservation security.

Citation: Woinarski, J. & Burbidge, A.A. 2016. Zyzomys pedunculatus. The IUCN Red List of Threatened Species 2016: e.T23324A22456932. . Downloaded on 24 September 2018.
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