Weyland Ringtail Possums (Pseudochirulus caroli) in the Weyland Mountains of Papua, Indonesia

by DerdriuMarriner

Animals can have strong senses of place. That happens when they narrowly define home. Weyland ringtail possums indeed have just one address: New Guinea's Weyland Mountains.

The southwest Pacific Ocean island of New Guinea does not number among the world’s inaccessible, isolated or remote land masses. It is accessible from northern Australia and insular Southern Asia. It lies immediately south of the Indonesian archipelago. Indonesian Papua meets independent Papua New Guinea at the island’s west-east borderline.

Despite different national cultures and divisive political boundaries, eastern and western New Guinea merge in similarly prevailing bio-geographies of accessibly fertile coastal lowlands and densely forested interior highlands. Papua Indonesia and Papua New Guinea also share similar animals and plants even though not all species live on both the island’s east and west sides. For example, only Papua Indonesia’s Weyland Mountains showcase Weyland ringtail possums.

Weyland Ringtail Possum (Pseudochirulus caroli) range

Distribution data from IUCN Red List.
Distribution data from IUCN Red List.


The east-to-west-running Central Highlands cut through the rugged interiors of both Papua Indonesia and Papua New Guinea. To the south of the Central Cordillera, the Weyland Mountains dominate west-central Papua Indonesia. They exhibit a prevailing surface geology of:

  • Limestone;
  • Sandstone;
  • Volcanics.

Their geography favors hills, mountains, plateaus, and valleys. They have as a politico-administrative address the Paniai division of the Indonesian province of Papua (Irian Jaya).  They include the photogenic Menoo valley and its picturesque Mount Kunupi. At an elevation of 6,003.94 feet (1,830 meters), Kunupi is the location of the Weyland ringtail possum specimens collected by Carl Brenders Pratt, as:

  • Brother of Felix Brenders Pratt;
  • Son of Antwerp Edgar Pratt (1850 - 1920).


Splendid astrapia (Astrapia splendidissima): splendid avian native of Mount Kunupi, Weyland Ringtail Possum homeland ~

illustration by Johannes Gerardus Keulemans (June 8, 1842 – March 29, 1912)
Plate V
Plate V


The first official descriptions of the Pratt specimens come from Millbrook-born British zoologist Michael Rogers Oldfield Thomas (February 21, 1858 – June 16, 1929), as:

  • Author of 1,000+ publications;
  • Identifier of 2,000+ specimens;
  • Mammalogist at the Natural History Museum.

They depict Weyland ringtails as classifiable into two subspecies:

  • The nominate described in 1921 and nowadays identified as Pseudochirulus caroli caroli;
  • The second described in 1922 and presently named Pseudochirulus caroli versteegi.

But it is possible that Oldfield’s identifications need to include disjunct populations. Weyland-dwelling ringtails in Bokondini, Baliem Valley may constitute:

  • Another subspecies;
  • Distinct species, per mammalogist Kristofer M. Helgen in 2007;
  • Existing subspecies, per mammalogist Timothy Flannery in 1995.


Michael Rogers Oldfield Thomas: first official description of Weyland Ringtail Possum

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)


Home ranges and physical features slightly differentiate subspecies. But all Weyland ringtails exhibit:

  • Big toes and thumbs respectively opposable to rear- and fore-paw digits;
  • Furry-based, prehensile (“grasping”) tail ring-curling into a hairlessly white tip;
  • Light brown limbs and paws;
  • Light grey-brown upper-coloring;
  • Mottled dark, white, yellow under-coloring;
  • Thick, woolly-soft fur.

They follow year-round breeding cycles which peak in April and May. Their life cycle is organized around maternally-dominated raising of yearly litters of 1 – 2 newborns. All newborns must:

  • Crawl from birth canals to maternal pouches;
  • Learn foraging and foraying while clinging to maternal backs at age 4 – 5 months;
  • Leave maternal nests with physical and sexual maturity.


Weyland ringtails attain adulthood with:

  • Dental formulas: 6 incisors, 2 canines, 6 premolars, and 8 molars and of 4 incisors, 6 premolars, and 8 molars respectively distributed evenly per upper and lower jaws;
  • Head-and-body lengths: 6.4 – 12.6 inches (16.26 – 32.0 centimeters);
  • Tail lengths: 6.7 – 15.8 inches (17.02 – 40.13 centimeters);
  • Weights: 15.52 ounces (440 grams).

They avoid predatory, rival conflicts by:

  • Communicating through body language and scent rather than sound;
  • Consuming bark, flowers, fruits, leaves, and small arthropods;
  • Moving through the trees rather than over the ground;
  • Recycling feces to maximize nutrition, sanitation and security and minimize travel-time.

They inhabit:

  • Nests of shredded bark and leaves;
  • Tree hollows.


Human environment in southern proximity to Weyland ringtail possum homelands: Korowai, reclusive, enthusiastic treehouse dwellers, live in swampy rain forest of Central Plateau, Indonesian sector of island of New Guinea.

Weyland ringtail possums display altitude versatility with habitats ranging from sea level coastal lowlands to mountainous elevations.
Korowai treehouse
Korowai treehouse


Scientists therefore consider Weyland ringtails arboreal, nocturnal marsupials that:

  • Favor life in the trees rather than on the ground;
  • Prefer nightly exercising, hunting and mating;
  • Raise newborns in frontally-opening pouches.

They designate Weyland ringtails as denizens of:

  • Brushlands;
  • Hill and montane tropical forests;
  • Rain and sclerophyll (“hard leaf”) forests;
  • Woodlands.

They know Weyland ringtail possums from:

  • Museum collections;
  • Official descriptions;
  • Village anecdotes.

They look to just 4 localities west of the Star Mountains as historically-proven sources of specimens even though they hypothesize broad home ranges and wide geographical distribution throughout Weyland Mountain elevations from coastal lowland interfaces at sea level to altitudes of 7,217.85 feet (2,200 meters).


Pseudochirops albertisii: disjunct population of altitude loving Albertis' silver green ringtails dwell in western ranges of Central Cordillera, sharing in Weyland ringtail homeland ~

illustration by Gustav Mützel (December 7, 1839 – October 29, 1893)
Wilhelm Peters and Giacomo Doria, "Enumerazione dei mammiferi" (1881), Tav. XI
Wilhelm Peters and Giacomo Doria, "Enumerazione dei mammiferi" (1881), Tav. XI


The rareness of a Weyland ringtail sighting acts as a blessing and a curse. It attests to the Weyland ringtail’s expertise in avoiding interactions and eluding predators. But it also frustrates accurate assessments of:

  • Environmental challenges;
  • Population sustainability.

It is somewhat ironic that ambiguity reigns since Weyland ringtail habitats coincide with such protected areas as:

  • Lorentz National Park;
  • Wardamen Strict Nature Reserve;
  • Weyland Mountain Strict Nature Reserve.

Protected areas theoretically operate to:

  • Conserve and preserve resources and wildlife;
  • Facilitate scientific research;
  • Soften the impact of modernity.

But they also protect native peoples who prey upon Weyland ringtails for:

  • Celebratory meat;
  • Ceremonial attire;
  • Practical clothing and instruments.


Puncak Jaya (also: Carstensz Pyramid), at elevation of 16,024 feet (4,884 meters), highest mountain on island of New Guinea:

Weyland ringtail possum landscape
Puncak Jaya: Grasberg copper mine pit in foreground; Puncak Jaya summit at far end of central rib
Puncak Jaya: Grasberg copper mine pit in foreground; Puncak Jaya summit at far end of central rib

Conclusion: Sustainability of Weyland ringtails in their vertiginous namesake mountains


High slopes and thick vegetation epitomize Earth's persisting enigmas. They exist throughout New Guinea. One of the many mysteries within the world's fourth-largest island's borders is the enigma of sylvan animals and plants specific to the Weyland Mountains' remote, towering, woody slopes. As a case in point, scientists know that Weyland ringtails are:

  • Elusive of predatory raptors and reptiles;
  • Mysterious in life cycles and natural histories;
  • Neighbors of D’Albertis’ ringtails (Pseudochirops albertisii);
  • Stressed by agro-industrialism, globally-warmed climate change, mining, and over-hunting.

Both non-specialists and specialists relish the challenge of mysteries and their resolutions. They understand that Weyland ringtail sustainability is realizable through:

  • Environmentally-friendly policies;
  • New Guinea pride in the entire island;
  • Protected areas;
  • Scientific research;
  • Visitor support.


thylacine (Thylacinus cynocephalus), endemic to Australia, New Guinea and Tasmania ~ widely thought to have become extinct in the 1930s

Weyland ringtails' backyard: sightings of thylacines reported in 1997 in the Baliem Valley, near Wamena, Jayawijaya Range, Maoke Mountains
"May 14, 1850: William Yarrell, Esq., V.P., in the Chair" (1850), Plate XVIII, opp. p. 89 ~ illustration by Joseph Wolf (January 21, 1820 – April 20, 1899)
"May 14, 1850: William Yarrell, Esq., V.P., in the Chair" (1850), Plate XVIII, opp. p. 89 ~ illustration by Joseph Wolf (Januar...



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


Treehouse of the Korowai tribe in Papua New Guinea.
Treehouse of the Korowai tribe in Papua New Guinea.

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a meeting place for modernity and tradition: Wamena, capital of Jayawijaya Regency and busy gateway in altitudinous Baliem Valley ~

Weyland ringtail possum landscape
Wamena Airport, Papua Province, Indonesia
Wamena Airport, Papua Province, Indonesia
the end which is also the beginning
the end which is also the beginning

Korowai Man Climbing Down from His Treehouse: photo by Johnny Haglund

Korowai Man Climbing Down from His Treehouse

New Guinea crocodile (Crocodylus novarguineae), denizen of freshwater lakes and swamps: photo by Ken Lucas

10x14 Photo Puzzle with 252 pieces. Packed in black cardboard box 5 5/8 x 7 5/8 x 1 1/5. Puzzle image 5x7 affixed to box top.
Photo Jigsaw Puzzle ~ Ardea Wildlife Pets

Dani Man in Front of His House Near the Baliem Gorge, Tangma, Irian Jaya, Indonesia: photo by Karl Lehmann

Dani people are among most populous tribes in Baliem Valley, a tableland at elevation of over 5250 feet (1600 meters) in Weyland ringtail homeland.
Dani Man in Front of His House Near the Baliem Gorge, Tangma, Irian Jaya, Indonesia

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: 01/03/2022, DerdriuMarriner
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DerdriuMarriner on 04/10/2014

VioletteRose, Me, too, I am glad to hear about species, thought to be extinct, have been hiding in plain sight all along.

VioletteRose on 04/09/2014

Great information about Weyland ringtail possums. Its also great to hear that the once thought extinct species, thylacines, are found again.

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