They are a cat-sized marsupial with a stocky build, dark greyish-brown fur, pale underparts and a long prehensile tail with a whitish tip.

Ngwayir forage at night through the upper canopy of trees, feeding on young leaves, flowers and fruit, especially in groves of the weeping peppermint Agonis flexuosa.

[2] Western ringtails are largely-arboreal marsupials smaller than the size of a domestic cat, with stocky bodies, grasping feet and a strong, prehensile tail.

[10] In the Swan Coastal Plain and South Coast, the species favours habitat dominated by Peppermint, as well as Tuart, Marri, Jarrah, Karri, Bullich, Albany Blackbutt, Allocasuarina, Banksia, Kunzea, Nuytsia, and Xylomelum.

[11][12] Urban populations surveyed in the city of Albany have revealed an average individual range of 0.88 hectares, moving from their dreys in the day to their preferred night-time habitat in eucalypts.

The study demonstrated that populations varied in their use of habitat and the size of the range was dependent on qualities such as the extent and connections of the canopy cover in its favoured tree species.

[10][14] Archaeological records and known locations estimate a historical range that extended southwest from Geraldton to the Hampton Tableland, 200 km west of the border of South Australia.

[13] Sheltering at ground level is recorded, though not usual, more frequently be found at hollows and the upper story of a forest; the species has occasionally be seen to occupy rabbit burrows.

[6] Western ringtails are folivorous; their diet includes leaves, shoots, fruit and flowers of a range of plants, both native and introduced.

[10] These threats include habitat loss and fragmentation, introduced predators (particularly the red fox), climate change, timber harvesting, and inappropriate fire regimes.