[11] On occasion they are recorded in the WA Wheatbelt and Goldfields regions, and by the 1930s disappeared completely from Swan Coastal Plain and surrounds.

[13] A solitary, mostly terrestrial nocturnal predator, the western quoll is most active around dusk (crepuscular) when it hunts.

During the day it seeks refuge in hollow logs or earth burrows as dens,[14] and saves energy by lowering its body temperature in its sleep.

This includes lizards, birds, frogs, spiders, insects, and small mammals; the largest it will eat is the size of a bandicoot or parrot.

[citation needed] Reintroduced populations in South Australia have been recorded preying on rabbits[16] and burrowing bettongs.

[12] During this time, the western quoll tends to take up large areas of habitat, and females aggressively defend their territory of 55–120 ha.

Land clearing, inappropriate fire regimes, grazing by stock and feral herbivores, illegal shooting, accidental drowning in water tanks, being hit by motor vehicles, and poisoning are all responsible for their disappearances.

[18] A five-year trial re-introduction of western quoll to the Flinders Ranges in South Australia began in April 2014.

[9] Despite the loss of about a third of the first release population (mostly due to predation by feral cats), most of the surviving females bred and sixty joeys were born.

[19] As of May 2016[update], a final release of 15 quolls from Western Australia was carried out in the Flinders Ranges, with a total population of 150.

[23] Animals were reintroduced to the semi-arid Mount Gibson Sanctuary in WA in April 2023, with the aid of feral predator control.

[24] Plans are in process to reintroduce the species to Dirk Hartog Island in Shark Bay,[25] Wardang Island[26] as part of the Marna Banggara[27] (formerly Great Southern Ark) project on the southern Yorke Peninsula[28] in South Australia, and large fenced reserves in the Pilliga Forest,[29] Mallee Cliffs National Park[30] and Sturt National Park,[31] all in NSW.

Captive breeding programs have contributed to reintroduction efforts, with Perth Zoo providing some animals for release.