Ngwayir (Pseudocheirus peregrinus occidentalis): Ringtail Possum of West Australia

by DerdriuMarriner

Scientists argue over ringtail possums. Is a westerner a common ringtail or another species? While experts debate, locals know that ngwayirs by any name are still ngwayirs.

Ringtail possums are mammals that come out nightly in Australia, Indonesia, and New Guinea, with the combined looks of:
• a bear in their ears,
• a housecat in their size,
• a kangaroo in their frontal pouches,
• a monkey in their end-coiling tail,
• a squirrel in their treetop agility.

Ngwayirs do not look like North America's 'possums even though their name does come from a seventeenth-century Powhatan word employed by the Virginia Algonquians, intended for the opossum (Didelphis virginiana), and translated as "white animal." Australia's ringtail possums generally go for coastal, insular and near-coastal eastern habitats.

The exception is the "false-handed occidental pilgrim," Pseudocheirus peregrinus occidentalis, the most controversial, vulnerable, and westerly of Australia's 17 species of ringtail possums.

extraordinary British zoologist Michael Rogers Oldfield Thomas:

portrait bequeathed by Oldfield Thomas to London's Natural History Museum
oil on canvas by John Ernest Breun (1862-1921)
oil on canvas by John Ernest Breun (1862-1921)


Millbrook-born British zoologist Michael Rogers Oldfield Thomas (February 21, 1858 – June 16, 1929) knew from an early age in Bedfordshire that he had a passion for observing and preserving wildlife in general and a talent for describing and identifying fauna in particular. He moved from distinguishing himself in studies at England’s Haileybury College in Hertford Heath to expanding scientific understanding of South Africa’s prolific insects on Table Mountain. He progressed in the British Museum from clerk for the Museum Secretary, 1876 – 1878, to Senior Assistant in charge of the Zoological Department’s collection of Mammals, 1878 – 1923. Contemporary and subsequent scientists respected Oldfield’s pioneer descriptions of 2,000 new species and subspecies in 1,000 published books, catalogues and documents.


Common ringtail possums are among the marsupials in which Oldfield specialized as a leading nineteenth- and twentieth-century mammalogist. Scientists in fact attribute to western ringtail possums separate species status as Pseudocheirus occidentalis on the basis of Oldfield’s comprehensive examinations and convincing identifications in the 1888-published Catalogue of the Marsupialia and Monotremata in the Collection of the British Museum (Natural History). Other experts back up continued subspecies status as Pseudocheirus peregrinus occidentalis on the basis of London-born William David Lindsay Ride’s (May 8, 1926 – November 6, 2011) expertise in Perth as:

  • Director of the Western Australian Museum;
  • Reader in Zoology at the University of Western Australia;
  • Writer of the 1970-published A Guide to the Native Mammals of Australia.


skull of Pseudocheirus occidentalis, viewed from above:

illustration by M.H. (Maud Horman) Fisher in Oldfield Thomas, Catalogue of the Marsupialia (1888)
Plate XIX Figure 3
Plate XIX Figure 3

side view: skull and upper jaw of Ngwayir

illustration by M.H. (Maud Horman) Fisher in Oldfield Thomas, Catalogue of the Marsupialia (1888)
Plate XVIII, Figure 6
Plate XVIII, Figure 6


Viewers of the ngwayir admire:

  • Big brown rounded eyes;
  • Black- and brown-tinged, grey-furred upper-parts;
  • Creamy-furred patches behind pink, round, small ears;
  • Creamy grey-furred under-parts;
  • Pink nose;
  • Long, white-tipped tail. 

Everyone indeed agrees on the beauty of western ringtail possums despite the ngwayir’s lack of the common ringtail’s signature rufous (red-brown) coloration. But upgrading to species status depends upon a published recommendation whose evidence passes refereed scrutiny. Continued downsizing as a subspecies recognizes contradictions between:

  • Albumin (water-dispersible globular proteins, versus water-insoluble fibrous and membrane proteins) immunology and electrophoretic (binding, charge, and size of molecules) studies against reclassification;
  • Karyotypes (chromosomal appearance and count of DNA and proteins in membrane-encased organelles within cells) and morphology (external appearance, internal structure) for reinstatement.


As the most abundant blood protein in mammals, serum albumin is studied, for example, for potential reclassifying into subspecies.

serum albumin structure
serum albumin structure


Ngwayirs are not born thickly-furred. Jellybean-sized newborns from autumnal or winter litters of one to three offspring crawl unaided to maternal pouchs after 2 – 4 weeks of gestation. They experience 3 – 4 pouch-confined months in which to bulk up to 4.41 ounces (125 grams) on maternal milk. Outside the pouch, they hold steady to milk-dominated diets until weaning at a weight of 19.4 ounces (550 grams) at age 6 – 8 months. At 8 – 12 months, males leave while females remain in or near maternal home ranges of 1.24 – 14.83 acres (0.5 – 6 hectares). Scientists suggest that males can access a total of 1,428.58 square miles (3,700 square kilometers) for forging new -- or sharing pre-existing -- home ranges.


Tuart tree is one of two trees selected by parental Ngwayirs as host trees for dreys (nests).

Tuart Tree (Eucalyptus gomphocephala) near Lake Clifton, Western Australia
Tuart Tree (Eucalyptus gomphocephala) near Lake Clifton, Western Australia


Dreys accommodate mature ngwayir dimensions of:

  • Head-and-body and tail lengths each at 1.25 – 1.57 inches (3.2 – 4 centimeters), with lower ranges describing females;
  • Weights at 1.81 – 2.87 pounds (0.82 – 1.3 kilograms), with upper ranges representing males.

Females and males begin their jointly-shared parental responsibilities of the next 2 – 5 years by building 5+ grass-, leaf- and twig-fortified nests in:

  • Balga grasstree (Xanthorrhoea preissii) canopies;
  • Tuart tree (Eucalyptus gomphocephala) canopies, forks and hollows.

Dreys fit three to six ngwayirs. They function as:

  • Beds by day;
  • Shelter from dingoes, foxes, owls and pythons;
  • Social centers.

They give access to crepuscular feedings on peppermint (Agonis flexuosa) flowers, fruits, leaves, and sap, with leafy supplements from:

  • Jarrah (Eucalyptus marginata);
  • Marri (Corymbia calophylla).


favorite crepuscular dining venue for Western Ringtail Possums: Peppermint Tree (Agonis flexuosa) flowers, foliage, fruits, and sap.

Agonis flexuosa grove on Swan River, Keanes Point, western Perth suburb of Peppermint Grove, Western Australia
Agonis flexuosa grove on Swan River, Keanes Point, western Perth suburb of Peppermint Grove, Western Australia

Ngwayir habitats


Ngwayir communities nowadays account for far more limited distributions and far smaller populations in comparison to the greater extent and numbers that scientists hypothesize for the historical presence of western ringtail possums in terms of geography and demographics. Ngwayirs still beautify West Australia’s coastal and near-coastal southwestern-most tip. They can be found in greatly reduced numbers in the areas of:

  • Busselton;
  • Collie River northeast of Bunbury;
  • Dingup State Forest near Manjimup;
  • Harvey River east of Harvey;
  • Leeuwin-Naturaliste, Porongurup, Waychinicup, and Yalgorup National Parks;
  • Perup and Two Peoples Bay Nature Reserves;
  • Southern Swan Coastal Plain.

Twenty-first century ngwayirs cluster in:

  • Forests and woodlands by preference;
  • National parks and nature reserves by re- and trans-location;
  • Residential gardens by circumstance.

Ngwayir habitats preferentially abound with:

  • Convenient access to such myrtle family (Myrtaceae) shrubs and trees as jarrah, marri and wandoo eucalyptus and peppermint willow myrtle;
  • Connecting corridors as conduits to genetically diverse communities (against geographically-imposed in-breeding);
  • Continuous mid- and upper-level canopy;
  • Maximum protection during peak birth months inland-wise of March to April and September to October and of April to June and October to December coast-wise;
  • Mediterranean-style weather of cool wet winters and dry warm summers;
  • Minimal wildfires;
  • Water sources such as floodplains, rivers, and swamps.

Ngwayirs accept as viable substitutes or supplements:

  • Abandoned rabbit burrows and hollow logs for ground-level shelters;
  • Heart-leaf poison bush (Gastrolobium grandiflorum) for main courses.

They appear defenseless against:

  • Developers;
  • Motorists;
  • Predators. 


Western Ringtail Possum (Pseudocheirus peregrinus occidentalis) range:

endemic species with constricted native habitat restricted to southwesternmost tip of coast and near-coastal Western Australia state, southwestern Australia
Distribution data from IUCN Red List
Distribution data from IUCN Red List



Conservationists accord ngwayirs the status of vulnerability to extinction. Amiable, beautiful, cautious, diminutive ngwayirs adapt to change by adopting garden edibles as food and subterranean burrows as shelters. But slight injuries afflict their sensitive immune systems. Slow vehicles aggrieve their low-energy metabolisms and waddling gaits. Global warming-provoked climate change aggravates their heat-sensitive physiologies, impacts water supplies, and re-times plant growth. Isolated from other ringtails, ngwayirs surely appreciate private and public initiatives to counter:

  • Competitive bushtail possums (Trichosurus vulpecula);
  • Fragmented habitats;
  • Geographically-induced in-breeding;
  • Naturalized predators.

Forests, parks, and reserves therefore assume pivotal roles in sustaining ngwayirs since wildland-urban interfaces theoretically:

  • Increase non-professional and professional awareness;
  • Respect human and wildlife rights to enjoying Earth’s bounty and ensuring future generations.


Western Ringtail Possum ~ "Nadia, a Western Ringtail possum, in temporary care at Roo Gully Wildlife Sanctuary before her rehabilitation back to the Australian bush."

Published on YouTube on June 26, 2010 by RooGully ~ URL:



My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.


Marri (Corymbia calophylla) foliage: appreciated by Ngwayirs

Eucalyptus (Corymbia) calophylla in flower, near Cataby, Western Australia
Eucalyptus (Corymbia) calophylla in flower, near Cataby, Western Australia

Sources Consulted

Bassarova, M.; Archer, M.; and Hand, S.J. December 20, 2001. “New Oligo-Miocene Pseudocheirids (Marsupialia) of the Genus Paljara from Riversleigh, Northwestern Queensland.” Memoirs of the Association of Australasian Palaeontologists 25:61-75. 

Clark, P; and Bradshaw, F. August 2007. “Haemotological Characteristics of Injured Western Ringtail Possums (Pseudocheirus occidentalis).” Comparative Clinical Pathology 16(3):187-192.

"Common Ringtail: Pseudocheirus peregrinus." Pp. 120-121 in Grzimek's Animal Life Encyclopedia, Second Edition. Volume 13: Mammals II, edited by Michael Hutchins, Devra G. Kleiman, Valerius Geist, and Melissa C. McDade. Farmington Hills, MI: Gale Group, Inc., division of Thomson Learning Inc., 2004.

Department of the Environment, Water, Heritage, and the Arts. 2009. Background Paper to EPBC Act Policy Statement 3.10 – Nationally Threatened Species and Ecological Communities. Significant Impact Guidelines for the Vulnerable Western Ringtail Possum (Pseudocheirus occidentalis) in the Southern Swan Coastal Plain, Western Australia. Canberra: Australian Government. Retrieved on February 26, 2014.

  • Available at:

Department of the Environment. 2014. " Pseudocheirus occidentalis -- Western Ringtail Possum, Ngwayir." Biodiversity Species Profile and Threats Database. Canberra: Australian Government. Retrieved on February 26, 2014. 

  • Available at:

Duff, Andrew; and Lawson, Ann. 2004. Mammals of the World: A Checklist. Yale University Press. 

Flannery, Timothy F. 1994. Possums of the World: A Monograph of the Phalangeroidea. Chastwood, Australia: GEO Productions in association with the Australian Museum.

Kerle, Jean Anne. 2001. Possums: The Brushtails, Ringtails and Greater Glider. Sydney: University of New South Wales Australian Natural History Series. Retrieved on February 26, 2014. 

  • Available at:

Macrini, Dr. Ted. 2007. “Pseudocheirus occidentalis, Western Ringtail Possum (On-line).” Digital Morphology. Retrieved on February 26, 2014.

  • Available at:

Menkhorst, Peter; and Knight, Frank. 2001. A Field Guide to the Mammals of Australia. South Melbourne: Oxford University Press. 

Meredith, Robert W.; Mendoza, Miguel A.; Roberts, Karen K.; Westerman, Michael; and Springer, Mark S. March 2, 2010. “A Phylogeny and Timescale for the Evolution of Pseudocheiridae (MarsupialiaDiprotodontia) in Australia and New Guinea.” Journal of Mammalian Evolution17(2):75-99. Retrieved on March 11, 2014.

  • Available at:

Morris, K.; Burbidge, A.; and Friend, T. 2008. “Pseudocheirus occidentalis.” In: IUCN 2013. International Union for Conservation of Nature and Natural Resources Red List of Threatened Species. Version 2013.2. Retrieved on February 26, 2014.

  • Available at:

Nowak, Ronald M. 1999. Walker's Mammals of the World, Sixth Edition. Volume I. Baltimore: Johns Hopkins University Press. 

Nowak, Ronald M. 2005. Walker's Marsupials of the World. Baltimore: Johns Hopkins University Press. 

"Pseudocheirus occidentalis: Western Ringtail Possum." Digital Morphology: A National Science Foundation Digital Library at University of Texas, Austin. Retrieved on April 4, 2014.

  • Available at:

Pseudocheirus peregrinus occidentalis: Western Ringtail Oppossum.” Encyclopedia of Life. Retrieved on February 26, 2014.

  • Available at:

Ride, W.D.L. A Guide to the Native Mammals of Australia. Melbourne: Oxford University Press, 1970.

Root, Nina J., and Bryan R. Johnson, comp. Proceedings of the Zoological Society of London: An Index to the Artists 1848 - 1900. New York and London: Garland Publishing Inc., 1986. Retrieved on February 26, 2014.

  • Available via Internet Archive at:

Strahan, Ronald; and Conder, Pamela. 2007. Dictionary of Australian and New Guinean Mammals. CSIRO Publishing.  

Thomas, Chris. "Hot spells threaten ringtail habitat." ScienceNetwork Western Australia > Topics > Environment & Conservation. September 18, 2013. ScienceNetwork Western Australia. Web.

  • Available at:

Thomas, Oldfield. Catalogue of the Marsupialia and Monotremata in the Collection of the British Museum (Natural History). London: Taylor and Francis (by Order of the Trustees), 1888. Retrieved on February 26, 2014.

  • Available via Biodiversity Heritage Library at:

Threatened Species Day Fact Sheet. 2007. “Western Ringtail Possum, Pseudocheirus occidentalis.” Department of the Environment and Water Resources Threatened Species and Ecological Communities Publications. Canberra: Australian Government. Retrieved on February 26, 2014.

  • Available at:

Wayne, A.F.; Rooney, J.F.; Ward, C.G.; Vellios, C.V.; and Lindemayer, D.B. 2005. “The Life History of Pseudocheirus occidentalis (Pseudocheiridae) in the Jarrah Forest of south-western Australia.” Australian Journal of Zoology 53(5):325-337.

"Western Ringtail Possum (Pseudocheirus occidentalis)." ARKive. Retrieved on February 26, 2014.

  • Available at:

"Western Ringtail Possum: Pseudocheirus occidentalis." Australian Threatened Species 2007. Retrieved on February 26, 2014.

  • Available at:

Wilson, D.E.; and Reeder, D.M. 2005. Mammal Species of the World: A Taxonomic and Geographic Reference, Third Edition. Johns Hopkins University Press.


Waychinicup National Park, Western Australia state: protected home of Ngwayir

Waychinicup River inlet
Waychinicup River inlet
the end which is also the beginning
the end which is also the beginning

2007 publication, based on Ronald Strahan’s first Dictionary of Australian mammals (published in 1981):

includes all species, both native and introduced
Dictionary of Australian and New Guinean Mammals

Salt and Algal Deposits at Lake Clifton, Yalgorup National Park, Mandurah, Western Australia: photo by Robert Francis

Western Australia's Yalgorup National Park is a translocation site for Ngwayirs (see above video "Relocating the western ringtail possum").
Salt and Algal Deposits at Lake Clifton, Yalgorup National Park, Mandurah, Western Australia

Me and my purrfectly purrfect Maine coon kittycat, Augusta "Gusty" Sunshine

Gusty and I thank you for reading this article and hope that our product selection interests you; Gusty Gus receives favorite treats from my commissions.
DerdriuMarriner, All Rights Reserved
DerdriuMarriner, All Rights Reserved
Updated: 08/02/2021, DerdriuMarriner
Thank you! Would you like to post a comment now?


Only logged-in users are allowed to comment. Login
DerdriuMarriner on 03/01/2014

Mira, It's amazing how much is accomplished -- and how quickly time flies -- when sharing interests, isn't it? Me, too, I love the eating sequences -- clearly this possum feels comfortable, feels cared for. There's a special soft spot in my heart for all ringtail species.

Mira on 02/26/2014

Wow, I can't imagine when you have time to do all the research, but it's fun to learn about all these mammals. I love that they relocated this ringtail possum to that national park in SW Australia. Also love the way it eats carrots :)

You might also like

Common Ringtail Possum (Pseudocheirus peregrinus) of Australia...

In Americanese, the word possum can apply to an opossum. In Australia, it can...

Rock-Haunting Ringtail Possum (Petropseudes dahli) of Groote E...

Rock ringtail possums are not nest-building tree-dwellers. They enjoy life am...

Disclosure: This page generates income for authors based on affiliate relationships with our partners, including Amazon, Google and others.
Loading ...