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

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.

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.

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.

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).

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. 

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.

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

oil on canvas by John Ernest Breun (1862-1921): Kristofer M. Helgen, Roberto Portela Miguez, James Kohen, Lauren Helgen/ZooKeys, CC BY 3.0, via Wikimedia Commons @ https://en.wikipedia.org/wiki/File:Portrait_of_Michael_Rogers_Oldfield_Thomas_-_ZooKeys-255-103-g003-bottom_right.jpeg; via Pensoft Publishers / ZooKeys @ https://zookeys.pensoft.net/showimg.php?filename=oo_25946.jpg

Plate XIX Figure 3: Public Domain, via Biodiversity Heritage Library @ https://www.biodiversitylibrary.org/page/37986833

Plate XVIII, Figure 6: Public Domain, via Biodiversity Heritage Library @ https://www.biodiversitylibrary.org/page/37986831

serum albumin structure: Jawahar Swaminathan and MSD staff at the European Bioinformatics Institute, Public Domain, via Wikimedia Commons @ https://en.wikipedia.org/wiki/File:PDB_1ao6_EBI.jpg

Tuart Tree (Eucalyptus gomphocephala) near Lake Clifton, Western Australia: SatuSuro, CC BY SA 3.0, via Wikimedia Commons @ https://en.wikipedia.org/wiki/File:TuartTree_nearlakeclifton.jpg

Agonis flexuosa grove on Swan River, Keanes Point, western Perth suburb of Peppermint Grove, Western Australia: Gordon Edwards (Gordon), CC BY SA 2.5, via Wikimedia Commons @ https://en.wikipedia.org/wiki/File:PeppermintGroveAtKeanesPoint.jpg

Distribution data from IUCN Red List: Chermundy / IUCN Red List of Threatened Species, species assessors and the authors of the spatial data, CC BY SA 3.0, via Wikimedia Commons @ https://en.wikipedia.org/wiki/File:Western_Ringtail_Possum_area.png

RooGully. "Western Ringtail Possum." YouTube, June 26, 2010, @ https://www.youtube.com/watch?v=ZOYoF1ZpLoM

Eucalyptus (Corymbia) calophylla in flower, near Cataby, Western Australia: Cas Liber, Public Domain, via Wikimedia Commons @ https://en.wikipedia.org/wiki/File:Eucalyptus_calophylla_flowers2_Cataby_email.jpg

Waychinicup River inlet: Hughesdarren, Public Domain, via Wikimedia Commons @ https://en.wikipedia.org/wiki/File:Waychinicup1.jpg

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