Australian Wildlife Conservancy (AWC) has reintroduced the Bilby to south-western Australia – returning this threatened species to the region for the first time in several decades through an initial translocation of 16 Bilbies from AWC’s Scotia Wildlife Sanctuary (NSW/SA border) to Mt Gibson Wildlife Sanctuary (WA).Read more...
Greater Stick-nest Rat
Range and abundance
The Greater Stick-nest Rat once ranged across semi-arid regions of southern Australia, including parts of Western Australia, South Australia and western New South Wales. However, the species declined rapidly after European colonisation, such that by the 1850s, it species was rare and restricted to areas that had not been grazed. Further declines meant that by the 1930s, the Greater Stick-nest Rat was extinct on the Australian mainland. Now, the only natural population of Greater Stick-nest Rats occurs on the Franklin Islands in South Australia.
In response to the massive species decline, a captive breeding program began in 1985. This program used animals from the Franklin Island population to boost population numbers so that some individuals could then be used in reintroductions. Using these captive-bred individuals, populations have been reintroduced to several other islands: Reevesby Island and St Peter’s Island in South Australia, and Salutation Island in Western Australia. As a result of further reintroductions, new populations of this species were established in various mainland areas. The earliest of these mainland populations was established at the Shark Bay Nature Reserve, Western Australia (1990). Later reintroductions were into the Venus Bay Conservation Park (1995) and Arid Recovery Reserve (1998), both in South Australia, and the Heirisson Prong Conservation Area (1999) in Western Australia. Although the success of these reintroductions has varied, most appear to have been reasonably successful, with self-sufficient and growing populations now established at several sites. AWC has reintroduced Greater Stick-nest Rats to Scotia and Mt Gibson sanctuaries.
Greater Stick-nest Rats are a large rodent, ranging from 17-26 cm in body length and weighing up to 450 g. They have fluffy yellow-brown to grey fur on their back and cream fur below. A blunt snout, large, dark eyes and large, rounded ears are also characteristic of the species. They also have a long tail that is dark brown above and light brown below, and distinctive white markings on their upper feet. When resting, Greater Stick-nest Rats sit in a hunched position that is similar to the stance of a rabbit.
As their name suggests, Stick-nest Rats builds huge, communal nests out of available sticks. Groups of 10 - 20 individuals work together to find and drag branches to a central site - usually around a bush that becomes part of the final nest. Branches are chewed to length and woven together with additionally-collected green vegetation. These nests can be up to 1 m in height and 1.5 m wide. Tunnels lead from the outside to the centre of these structures, where rats place grass and other soft green vegetation. These nests provide protection for the rats from native predators.
Greater Stick-nest Rats are herbivores, feeding on the leaves and fruits of a wide variety of other species, with a preference for succulent and semi-succulent plants. Breeding can occur year-round but usually peaks in autumn and winter. Females give birth to between one and three young. These young are well-developed at birth and secure themselves tightly to their mother’s teats. They are dragged around by the mother for about a month, until weaning and independence.
Like most other small to medium-sized Australian mammals, Greater Stick-nest Rats are highly susceptible to predation by foxes and cats. Introduced herbivores would have exacerbated population declines by competing for food and trampling nests.
Remaining and reintroduced populations on islands and in predator-free enclosures do not immediately face threats from introduced predators or herbivores. However, these populations are small and geographically isolated, and at risk of extinction from localised catastrophic events such as fire, disease, or incursions of feral predators.
What is AWC doing?
AWC has reintroduced Greater Stick-nest rats to a 5 ha breeding enclosure at Mt Gibson. Animals from the enclosure will be released to the 7800 ha Mt Gibson Endangered Wildlife Restoration Project upon completion of the 40 km predator-proof fence. AWC has previously introduced Greater Stick-nest Rats to Scotia Wildlife Sanctuary and Faure Island. The Scotia population is considered extant, but attempts to monitor known nest sites have been hindered by other reintroduced species. The reintroduction to Faure was not successful. Another attempt will be made in the future, building on the experience of the reintroduction to Mt Gibson.