No subspecies are recognised

There have been no specimens of the Crescent Nail-tailed Wallaby since 1908 and no reliable sight records since the 1940s (Abbott 2008b; Burbidge 2023).

Four types of probabilistic models to estimate the probability of extinction and the date of extinction of this species have been published (Fisher and Humphries 2024): a 1) Stationary Poisson (Solow 1993), a Weibull model (Roberts and Solow 2003), a Nonparametric model (Solow and Smith 2005), and Threat & effort Cox Regression Survival model (Fisher and Blomberg 2012). All concluded that this species is extinct with >90% probability. The estimated extinction date was 1963 (Fisher and Blomberg 2012).

The Crescent Nail-tailed Wallaby was widespread in semi-arid south-western Australia, in the western deserts of Western Australia, the Northern Territory and South Australia, and in south-western New South Wales and south-eastern South Australia (Short 2004, Burbidge 2023).

The Crescent Nail-tailed Wallaby is extinct. It was apparently abundant in the Western Australian wheatbelt in the early 1900s as Guy Shortridge collected 23 specimens for the British Museum from near Pingelly and Wagin (Burbidge 2023).

John Gilbert, who collected specimens for John Gould in the 1830s, noted that the Crescent Nail-tailed Wallaby was ‘found in the gum forests of the interior of Western Australia, where there are patches of thick scrub and dense thickets, in the open glades intervening between which it is occasionally seen sunning itself, but at the slightest alarm immediately takes itself to the shelter of the thick scrub’ (Gould 1863). (Gilbert’s ‘forests’ would today be termed woodlands.) John Gilbert reported to Gould (1863) that ‘it makes no nest, but forms a hollow in the soft ground beneath a thick brush in which it lies during the heat of the day’. Bruce Leake, an early settler of Kellerberrin, reported that it inhabited open timbered country and that when chased would make for a tree with a hollow in the bottom and clamber up the sides until it got some distance up into the tree (Leake 1962).

Aboriginal people from the western deserts recalled that it inhabited most types of country, including stony hills, and was particularly abundant in mulga (Acacia aneura) country. They said it ate grass and sheltered lying on its side under a low shady tree or shrub (Burbidge et al. 1988). Aboriginal people from the Flinders Ranges of South Australia recalled that it lived throughout the ranges and on the adjacent plains (Tunbridge 1991).

This species was probably extirpated by predation from introduced Red Foxes Vulpes vulpes and feral Cats Felis catus. Cats were widespread in the species’ range by the 1890s (Abbott 2008a). There is abundant evidence that feral Cats have a significant effect on medium-sized Australian mammals, including causing extinction (Dickman 1996). The Red Fox arrived in the south-west of Western Australia in the 1920s (Abbott 2008b). Habitat degradation, including changing fire regimes and the impact of rabbits and introduced stock, may have had an impact, especially in combination with predation. In part of its former range (south-western Western Australia and parts of New South Wales), pastoral expansion leading to habitat degradation, mainly by sheep, was likely to have been detrimental to the species. There is some evidence for epizootic disease as a contributing factor, possibly interacting with drought and predation (Abbott 2006).
There is evidence for epizootic disease as a contributing factor to extinction of many mammal species in Western Australia. Many of these species declined before the arrival of foxes; however, this epizootic did not greatly affect arid zone mammals (Abbott 2006). Cats were widespread in the species’ range by the 1890s (Abbott 2002b, 2008). There is abundant evidence that feral Cats have a significant effect on medium-sized Australian mammals, including causing extinction (Dickman 1996). The Red Fox, which also had a detrimental effect on medium-sized Australian mammals Kinnear et al. 2002), arrived in the south-west of Western Australia in the 1920s (Abbott 2008a).

The species is extinct.