Leporillus Conditor Research Articles

Catastrophic drought-induced die-off of perennial chenopod shrubs in arid Australia following intensive cattle browsing

Cover and survivorship of perennial chenopods, Atriplex vesicaria and Maireana astrotricha, declined markedly during a prolonged dry period at Roxby Downs in arid South Australia. Despite their resilience to browsing in favourable seasons, only 2% of the A. vesicaria shrubs browsed heavily by cattle survived the drought. M. astrotricha exhibited greater drought survivorship, although the post-drought cover retention in browsed shrubs was only half that of unbrowsed controls. Survivorship was highest for unbrowsed chenopods growing in moisture-enhanced run-on or dune-base environments. Maintenance of these patchy areas with reduced water-stress is hence important for the persistence of browsed chenopod shrublands. Light browsing by either European Rabbits ( Oryctolagus cuniculus) or Greater Stick-nest Rats ( Leporillus conditor) had no measurable impact upon chenopod survivorship.

The activity of Sand Goannas Varanus gouldii and their interaction with reintroduced Greater Stick-nest Rats Leporillus conditor

The activity pattern of the Sand Goanna Varanus gouldii in northern South Australia was estimated by radio telemetryduring the summer months. Individuals were located within the Arid Recovery Reserve where introduced European Rabbits Oryctolagus cunniculus, Feral Cats Felis catus and European Foxes Vulpes vulpes were removed. Interaction between the re-introduced Greater Stick-nest Rat Leporillus conditor and the Sand Goanna, a potential significant predator in the absence of cats and foxes, was examined. Mean activity area for Sand Goannas was 5.9 ha (�1.0, n = 9), and their summer activity was concentrated on sand dunes rather than the adjacent inter-dunal swales. Tracks of Sand Goannas were found more often around Greater Stick-nest Rat nests than control sites. However, Sand Goanna predation on re-introduced Greater Stick-nest Rats could not be confirmed and most deaths of radio-collared Greater Stick-nest Rats coincided with a period of exceptionally high maximum temperatures and were probably due to heat and dehydration. Sand Goannas scavenged Greater Stick-nest Rat carcasses, and analysis of scats and stomach material revealed that although invertebrates were the most common prey item, mammal material (hair and bones) was present in 20% of scats.

Comparative foraging preferences of the greater stick-nest rat Leporillus conditor and the European rabbit Oryctolagus cuniculus: implications for regeneration of arid lands.

Dietary preferences of the greater stick-nest rat (Leporillus conditor) and the European rabbit (Oryctolagus cuniculus) were compared using cafeteria trials and direct observations. Despite overlap, these species exhibited differences in dietary preference. L. conditor showed a strong preference for chenopod shrub species and other plant species with a high water content including Gunniopsis quadrifida and Calandrinia remota. L. conditor also preferred female bladder saltbush (Atriplex vesicaria) foliage to male. O. cuniculus ate a greater selection of plant species in most trials with their most preferred species including mulga (Acacia aneura), Salsola kali and Calandrinia remota. Both O. cuniculus and L. conditor preferred seedlings of perennial species to adult cuttings. L. conditor has recently been re-introduced to a 14 km� O. cuniculus, cat (Felis catus) and red fox (Vulpes vulpes) proof exclosure in the arid zone of South Australia. The re-introduction of this herbivore and the removal of exotic herbivores may change the vegetation structure and composition within the exclosure by restricting growth of some succulent chenopod species but allowing the regeneration of tall shrub species such as Acacia aneura which are usually limited by O. cuniculus grazing.

The record of fauna, and accumulating agents of hair and bone, found in middens of stick-nest rats (Genus Leporillus) (Rodentia : Muridae)

Middens built by stick-nest rats (Leporillus apicalis and/or Leporillus conditor) contain information relating to the animals that lived in the arid areas of Australia. The hair and bones recovered from stick-nest rat middens in the Northern Territory, South Australia and Western Australia provide information about the former distribution and community composition of species in arid Australia. Some of the species recorded from the middens are no longer present in the surrounding areas. The bone and hair materials appear to have been derived from the scats of small carnivorous mammals and incorporated into middens by stick-nest rats. The material has been radiocarbon dated and, in some cases, represents over 2000 years of accumulation in the middens of stick-nest rats.

The status and conservation of native rodents in Western Australia

This paper examines the conservation status of Western Australia’s native rodent fauna using IUCN criteria and compares this with their current status under State and Commonwealth legislation, as well as that recommended in the Rodent Action Plan. Of the 35 native rodent taxa known in Western Australia, four (11%) are currently listed as extinct, and six (17%) as threatened under Western Australian legislation. Nine are listed as threatened under Commonwealth legislation. It is proposed that two, currently unlisted, island sub-species should be regarded as threatened. Some decreases in conservation status are also proposed. Predation by feral cats, habitat destruction and the use of surface shelter structures are suggested as primary factors in the decline of native rodents. Conservation programs are underway for most threatened taxa in Western Australia, including the implementation of recovery plans for the Shark Bay mouse and greater stick-nest rat. The heath rat is the only threatened rodent lacking a conservation program in Western Australia. The work planned or required for rodent conservation is presented and includes survey for the critically endangered central rock-rat, and translocation programs for other threatened taxa. The distribution of most taxa is relatively well known; however, there is a need to commence, or complete, taxonomic assessment of some.

Reproduction and Captive Breeding as a Tool for Mammal Conservation: The Role of Modem Zoos.

There is a growing awareness in the scientific research community of the role that zoological institutions can play in the conservation of threatened or endangered species. Zoos themselves have changed and become more focussed on the contributions they can make to regional conservation objectives, driven in part by the "World Zoo Conservation Strategy" published in 1993. Perth Zoo has committed itself to this strategy and established a collaborative scientific research program with Conservation and Land Management (CALM), WA, to develop captive breeding techniques for a number of Western Australian native species. To achieve this objective, the zoo has established a sub-program known as the Native Species Breeding Program. This consists of 6 specialist keepers who are charged with developing specialised skills in captive husbandry of selected species, and the implementation of research projects. All of the species under study are part of recovery plans, and many of the species are being produced for release under the objectives of those plans and as part of CALM's "Western Shield Project". Mammal species under study are the Numbat, Chuditch, Dibbler, Djoongari (Shark Bay Mouse) and the Wopilkara (Greater Stick Nest Rat). Currently, Chuditch, Numbats and Djoongari bred in captivity have been the subject of re-introduction programs. The results of these breeding programs and the subsequent releases of selected species into different habitats in Western Australia will be presented, along with a discussion of the issues which relate to the limitations of captive breeding as a conservation tool.

Natural histories of Australia’s stick-nest rats, genus Leporillus (Rodentia : Muridae)

The former distributions of stick-nest rats (Leporillus conditor and L. apicalis), both extinct on the Australian mainland since about the 1930s, were determined from literature reports, museum records, interview responses and field surveys of key areas. Population parameters were determined for L. conditor from early literature accounts, studies of remnant stick-nests in caves, a three-year study of the last known naturally-occurring populations on the Franklin Islands, records maintained for a captive-breeding program since 1986, and further population data obtained during systematic monitoring of reintroduced populations. Comparable data for L. apicalis could be obtained only from early literature accounts and remnant stick- nests in caves; this species has not been recorded since 1933 and is presumed extinct. Leporillus conditor is a predominantly ground-dwelling, herbivorous rodent of semi-arid, perennial shrubland habitats, which builds nests of interwoven sticks for protection from the elements and from predators. Leporillus apicalis apparently occupied similar habitats, often in sympatry with L. conditor, but extended its range further into the arid zone and may have had a more arboreal life-style and a more diverse diet, including invertebrates. The demise of both species from the mainland was almost certainly due to severe habitat degradation caused by introduced herbivores (mainly rabbits and sheep) before, and leading into, severe drought conditions. The resulting reduction in availability of food and cover also led to an increased vulnerability to predation (primarily by foxes, cats, dingoes and owls). In current L. conditor populations, females reproduce throughout the year and have well-defined home- ranges with relatively small core activity areas. Males have considerably larger home ranges. Predation by owls, especially barn owls (Tyto alba) is a significant cause of Leporillus mortalities, highlighting the importance of cover for the rats’ survival.

A discussion of the large extinct rodents of Mootwingee National Park, western New South Wales

Four large rodent species (Greater Stick-nest Rat Leporillus conditor, Long-tailed Hopping-mouse Notomys longicaudatus. Plains Rat Pseudomys australis and Long-haired Rat Rattus villosissimus) have been identified among the subfossil remains collected at Mootwingee National Park, western New South Wales. These records are at the periphery of the published distributions for most of the species and represent an addition to the fauna recorded for the Mootwingee area.

Introduction of a Brachylaima species (Digenea: Brachylaimidae) to Australia

Introduction of a Brachylaima species (Digenea: Brachylaimidae) to Australia. International Journal for Parasitology 20: 789–796. A Brachylaima species recorded previously from the house mouse ( Mus domesticus) in South Australia is shown to use the introduced European snails Cernuella virgata and Cochlicella barbara as first intermediate hosts, and the same two species and Theba pisana as second intermediate hosts. The life cycle is typical of Brachylaima species. The parasite is capable of infecting at least two species of native Australian rodent, Rattus fuscipes and Leporillus conditor. Because of the intermediate hosts used, it is hypothesized that this trematode species has been introduced from Europe. The parasite may be conspecific with one of a number of described European species but difficulties with the literature concerning these species have required that the present form be designated only as Brachylaima sp.

Identities of the rodents (Muridae) listed in T. L. Mitchell's "Three expeditions into the interior of eastern Australia, with descriptions of the recently explored region of Australia Felix, and of the present colony of New South Wales" (1st ed., 1838; 2nd ed., 1839).

Mitchell applied four names to the rodents collected during his exploration of New South Wales and Victoria in 1831-36. They are "Dipus Mitchellii. Ogilby [Dipus mitchellii Ogilby, 1838]", "Conilurus constructor. Ogilby [Conilurus constructor (Ogilby, 1837))", "Mus Platurus Mitch. [Mus platurus Mitchell, 1838]" and "Mus Hovellii. Mitch. [Mus hovellii Mitchell, 1838] ". M. platurus Mitchell and M. hovellii Mitchell are nomina nuda. The whereabouts of the specimens are unknown. One is the holotype of Notomys mitchellii (Ogilby, 1838). The identities of the others are in doubt, but Conilurus albipes (Lichtenstein, 1829), Leporillus conditor (Sturt, 1848) and Leporillus apicalis (Gould, 1853) may all be represented in Mitchell's collec tion. The original descriptions of D. mitchellii Ogilby and C. constructor (Ogilby) are in abstracts of a paper read to the Linnean Society of London on December 5th, 1837. A lectotype is designated for Conylurus constructor Ogilby, 1837 and for Conilurus constructor Ogilby, 1838. The former name is an unused one and l will be making an application to the International Commission on Zoological Nomenclature asking that the name be suppressed. The publication date of 1829 attributed here to Hapalotis albipes Lichtenstein is derived from external evidence. The evidence for Leporillus apicalis being a stick-nest builder is inconclusive, but it probably has that habit. Conilurus albipes is apparently extinct. Notomys mitchellii still occurs in northwestern Victoria. Leporillus apicalis may be extant in remote areas of the continent. Leporillus conditor presumably continues to survive on Franklin Island, off the South Australian coast. It may also be extant on the Australian mainland.

The sticknest rat, Leporillus conditor, on Franklin Island, Nuyts Archipelago, South Australia.

On Franklin Island, South Australia, Leporillus conditor, occurred in all vegetation associations, although the density varied between these associations. The animals built sticknests ranging from a few twigs added to a shrub to a conical nest I.5 m high built entirely by the rats. Stomach contents of three animals contained only plant items. Predators include barn owls and possibly black tiger snakes. Leporillus conditor appears to breed opportunistically with a gestation period of approximately 44 days and a litter size of one or two. The population on Franklin Island in March 1970 was estimated to number between 1,500 and 2,000 individuals. The decline of mainland populations appears to have followed the advent of grazing by sheep and cattle.