THREATENED SPECIES SCIENTIFIC COMMITTEE Established under the Environment Protection and Biodiversity Conservation Act 1999 The Minister’s delegate approved this Conservation Advice on 16/12/2016 . Conservation Advice Zyzomys palatalis Carpentarian rock-rat Conservation Status Zyzomys palatalis (Carpentarian rock-rat) is listed as Endangered under the Environment Protection and Biodiversity Conservation Act 1999 (Cwlth) (EPBC Act) effective from the 16 July 2000. The species was eligible for listing under the EPBC Act as on 16 July 2000 it was listed as Endangered under Schedule 1 of the preceding Act, the Endangered Species Protection Act 1992 (Cwlth). Species can also be listed as threatened under state and territory legislation. For information on the current listing status of this species under relevant state or territory legislation, see http://www.environment.gov.au/cgi-bin/sprat/public/sprat.pl . The main factors that are the cause of the species being eligible for listing in the Endangered category are a restricted geographic range, fragmented distribution, small population size and decline in habitat quality. The Committee notes that the Action Plan for Australian Mammals 2012 (Woinarski et al., 2014) reviewed the conservation status of all Australian mammals and the review of the Carpentarian rock-rat considered it to be Critically Endangered. This differs from the status determined when the species was grandfathered in from the Endangered Species Protection Act 1992 (Cwlth). The Threatened Species Scientific Committee is using the findings of Woinarski et al., (2014) to prioritise future reassessment of the conservation status of each of threatened mammals listed under the EPBC Act. Description The Carpentarian rock-rat is one of five species of rock-rat in the Australian endemic genus Zyzomys . All species are similar in gross morphology and diet, though Z. argurus (common rock-rat) is substantially smaller than the other four species. Four species are restricted to northern Australia (three of which have very limited ranges): the fifth species, Z. pedunculatus (central rock-rat), occurs only in central Australia. The rock-rats are characterised by “compact, harsh-furred bodies, pronounced roman-nosed appearance, rounded ears, and protruding eyes” (Watts & Aslin 1981), and especially by the fragile carrot-shaped tail, in which fat is deposited. They also have notably long whiskers. The Carpentarian rock-rat is very similar in appearance to Z. woodwardi (Arnhem Land rock-rat) and Z. maini (Kimberley rock-rat). It is grey-brown above and white below. The tail is relatively hairy, with especially long hairs towards the tip. Body weight averages about 120g. As with other rock- rats, Z. palatalis is known to lose its tail, fur and skin very easily (Puckey et al., 2001). Distribution The Carpentarian rock-rat is known only from one pastoral property (Wollogorang) in the Gulf of Carpentaria hinterland, Northern Territory. Within this area it is known from six disjunct sites, mostly gorges and scree slopes, all within a radius of about 40 km (Puckey 2003; Woinarski et al., 2007). The extent of movement of individuals between sites is not known, but is assumed to be very low, so the sites are considered subpopulations. A series of surveys in suitable habitat in neighbouring areas (sampling of > 40 sites) of the Northern Territory failed to record further Zyzomys palatalis (Carpentarian rock-rat) Conservation Advice Page 1 of 7 subpopulations (Trainor et al., 2000), and the species was not recorded in an extensive survey in comparable habitat in nearby areas of Queensland (White & Mason 2011). There are no fossil records. No known populations have become extinct, possibly because the species was only discovered as recently as 1986 (Kitchener 1989). Relevant Biology/Ecology The Carpentarian rock-rat is now strongly associated with monsoon thickets (dry rainforest) occurring on rocky slopes within large gorge systems (Churchill 1996; Trainor 1996b; Trainor et al., 2000; Puckey et al., 2004), but its range also extends to adjacent eucalypt woodlands with hummock grass ( Triodia spp.) understorey (Puckey et al., 2004). It is possible that its previous distribution encompassed a broader range of habitats. The rainforest patches where the species now occurs are considered to be habitat critical to the survival of the species. Plant species characteristic of this habitat include Pouteria sericea (common names include wild prune, Mangarr, Mongo), Terminalia subacroptera (pear tree), T. volucris (rosewood, yellow wood), Celtis philippensis (no common name recorded), Ficus leucotricha (common names include native fig, rock fig), F. virens (common names include deciduous fig, mountain fig, banyan), Cissus reniformis (Cissus), Caesalpinia bonduc (common names include grey-nicker, knicker nut) and Gyrocarpus americanus (common names include helicopter tree, corkwood) (Puckey et al., 2001). Populations are often within 100 m of permanent spring water (Lee 1995). The Carpentarian rock-rat is a nocturnal rodent, sheltering during the day in cracks between boulders, caves and crevices. It forages on the ground, and much of its diet comprises fruits and seeds of fleshy-fruited plants, including pear tree, T. carpentariae (wild peach, billy goat plum), Ficus spp. and Pandanus aquaticus (pandanus, river pandanus, srew-palm) (Trainor 1996a; Puckey et al., 2001). Its large incisors allow it to chew through the woody nuts of many of these species to access the kernel, and distinctively chewed nuts are a characteristic sign of its presence (Puckey et al., 2001). Information from the more intensively-studied Arnhem Land rock-rat (Begg & Dunlop 1980, 1985) is probably generally applicable to the Carpentarian rock- rat (Puckey et al., 2001). There is no significant difference in the size of the home range or core area of males and females, though juveniles have a significantly smaller home range than adults. The species is noted to prefer the slopes and valley area of gorges, or the ecotone between these two areas, rather than the surrounding plateaus, making many short distance foraging moves interspersed with longer forays that occur irregularly (Puckey et al., 2004). Based on a radio-tracking study of 21 individuals, Puckey et al. (2004) calculated a mean home range size of 1.1 ha and found that individuals may move up to 2 km in one night. While most activity occurred within monsoon rainforests, some individuals would also forage within nearby areas of savanna woodland. No animals moved more than 80 m away from the edge of rainforest (Puckey et al., 2004). As with all rock-rats, reproductive output is characteristically low. Carpentarian rock-rats generally have a 1:1 sex ratio in the population and females give birth to 1 - 3 young per litter (Trainor 1996a). However, breeding has been reported in most months, and females living into their second year can produce up to four litters (Trainor 1996a; Trainor et al., 2000). Growth of young is unusually rapid (Watts & Aslin 1981), perhaps allowing for more frequent breeding events (Puckey et al., 2001). There are very limited data on longevity, territoriality and age structure of Carpentarian rock-rats. From information for other Zyzomys species, mean age at sexual maturity is estimated at 5 - 6 months (Begg 1981) and longevity at 2 - 3 years (Woinarski et al., 2014). There appears to be a substantial seasonal fluctuation in the abundance of Carpentarian rock- rats, with relatively low numbers reported from January to June. It is unclear whether this is due to movements away from the habitats sampled in studies based on permanent grids, seasonal changes in trapability or real changes in population numbers (Puckey et al., 2001). Zyzomys palatalis (Carpentarian rock-rat) Conservation Advice Page 2 of 7 Threats Extensive, frequent and intensive fires are a known threat to the species. Impacts from fires could interact with, and be compounded by, other suspected threats such as predation by feral cats and climate change (Table 1). Table 1 – Threats impacting the Carpentarian rock-rat in approximate order of severity of current risk, based on available evidence. Threat factor Threat Evidence base type and status Fire Extensive, known Monsoon rainforests are known to be fire-sensitive (Russell- frequent and current Smith & Bowman 1992); monsoon thickets on rocky slopes are intense fires vulnerable to intense fires (Puckey et al., 2001). The regional regime of frequent, extensive and high intensity fires (Perry et al., 2011; Harrington & Murphy 2015) may lead to reductions in habitat extent, habitat quality and food resources, and prevent the establishment of new populations (by dispersal or translocation). Population viability analysis (PVA) by Brook et al. (2002) predicted that the species' sensitivity to frequent, hot, late dry- season fires, together with progressive habitat degradation, is likely to substantially reduce the overall population size and lead to the probable extinction of the species within 100 years. However, data from Bowman et al. (2006) suggests that habitat loss has not been so severe, and that the PVA may have been incorrect . Invasive species Predation by suspected Cats are known to inhabitat the area and could have a feral cats current negative effect on the small and isolated populations of (Felis catus ) Carpentarian rock-rats. However, the rugged nature of their habitat may constrain the incidence and impact of predation by cats (Woinarski et al., 2014). Weed suspected