The common ringtail possum (Pseudocheirus peregrinus, Greek for "false hand" and Latin for "pilgrim" or "alien") is an Australian marsupial.

This possum also consumes caecotropes, which is material fermented in the caecum and expelled during the daytime when it is resting in a nest.

Several subspecies have been described:[1] Pseudocheirus occidentalis (Ngwayir, or the Western ringtail possum), found in the south west of Australia, used to be considered a subspecies of Pseudocheirus peregrinus; however, it is now formally considered a separate species.

[7] The common ringtail possum feeds on a wide variety of plants in the family Myrtaceae including the foliage, flowers and fruits from shrubs and lower canopy.

[8] Some populations are also known to feed on the leaves of cypress pine (Callitris), wattles (Acacia spp.)

One study found the emergence of young possums from their pouches corresponds to the flowering and fruiting of the tea-tree, Leptospermum and the peak of fresh plant growth.

The possum's gastrointestinal tract sends the fine particles to the caecum and the coarse ones to the colon.

[4] These particles stay in the caecum for up to 70 hours where the cell walls and tanned cytoplasts are partially digested.

[12] What distinguishes the digestive system of the common ringtail possum from that of the koala and the greater glider is the caecal contents are expelled as caecotropes, reingested and passed into the stomach.

[14] The common ringtail possum has a daily maintenance nitrogen requirement (MNR) of 290 mg N/kg0.75.

[4] The ringtail possum recycles 96% of its liver's urea, which is then transferred into the caecum and made into bacterial protein.

Only re-ingestion makes this effective and the bacterial protein must be digested in the stomach and the amino acids subsequently absorbed in the small intestine.

Reingestion allows the possum to live on low nitrogen eucalyptus leaves which is particularly important during late lactation.

[17] Common ringtail possums live a gregarious lifestyle which centres on their communal nests, also called dreys.

[19] The long lactation of the ringtail possums may give the young more time to learn skills in the communal nest as well as to climb and forage in the trees.