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

Abstract

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.