Petropseudes dahli

Geographic Range

Rock ringtail possums are found in rocky terrain, usually sandstone outcroppings, in a small portion of northern Australia. The species has a wide distribution in northern Australia. Most commonly the species is found in the Northern Territory, Kimberley, Katherine, and Queensland.

• Biogeographic Regions
• australian australian
  • native native

Habitat

Rock ringtail possums live in rocky, sandstone outcrops where they are sheltered during the day. At night they move out of their sheltered rock crevices to feed in the trees within the area, often traveling no further than 10 meters from their dens. These rocky areas usually are surrounded by flatter, lowland areas. The rocky encampments have increased water holding potential and are sometimes flooded in areas.

• Habitat Regions
• tropical tropical
• terrestrial terrestrial

• Terrestrial Biomes
• scrub forest scrub forest

Physical Description

Rock ringtail possums are small, stocky possums, similar in size to a small rabbit. The pelage is grey to reddish-grey on the back and a lighter, cream color on the underside. There is a dark stripe down the middle of their backs. The coat is long and thick. The tail is unique in that it is furred only half-way down, it lacks scales on the unfurred portion of the tail, unlike some of their close relatives. Rock ringtail possums have small, rounded ears. They have white hair in patches both above and below the eyes and underneath the ears. Rock ringtail possums live in rocky areas and have developed many adaptations to a more terrestrial lifestyle than many of their relatives . They have shorter legs, claws, and tails. As in other possums, the tail is prehensile.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• female larger

Reproduction

Petropseudes dahli is one of few obligate monogamous marsupial species. Females live in their home range with one male. Scent posts are used commonly by the species to define home range and to mark territories. Family groups are tightly knit and consist of the mother, father, and one or occasionally two offspring. Young help with raising their younger siblings.

• Mating System
• monogamous monogamous
• cooperative breeder cooperative breeder

There does not appear to be a restricted breeding season. There is normally one offspring, with occasionally two. No gestation period information is available for the species but close relatives have gestation periods from 16 to 30 days. Females have a large pouch with two teats where the new offspring spends its first five weeks. The current year's offspring are often found on the back of their parent's or nearby after leaving the safety of their mothers pouch. Previous offspring will commonly stay with the family unit to assist in rearing the next offspring.

• Key Reproductive Features
• iteroparous iteroparous
• year-round breeding year-round breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• viviparous viviparous

There is an extensive amount of parental care in this species. Rock ringtail possums live in tight knit family groups. Care of young is undertaken by both parents and young of the previous breeding effort. Care of young is divided nearly equally between the two parents after weaning. Prior to weaning the offspring spends its time in its mothers pouch receiving nourishment from her milk. After exiting the pouch, both parents spend time grooming, resting with, and greeting their young. Mother and father both also practice several protective behaviors. Both parents spend time watching for predators, beating their tails, vocalizing, and keeping young relatively close. Females nursing young in their pouches can become defensive, on occassion even towards their mate. This behavior ranges from swinging of limbs towards counterpart or making growls or grunts. Mothers may also show some slight aggression towards subadults if they interfere with her activities or young.

• Parental Investment
• altricial altricial
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • male
    • female
• pre-independence
  • protecting
    • male
    • female
• post-independence association with parents
• extended period of juvenile learning

Lifespan/Longevity

There is no information on longevity of rock ringtail possums. A closely related species, Leadbeater's possums ( Gymnobelideus leadbeateri ), live more than 10 years in captivity. In the wild this same species has a maximum longevity of 5 years.

Behavior

Rock ringtail possums are social, living in tight knit family groups. These groups are usually made up of about 4 individuals, although group sizes of two 2 to 10 individuals are reported. They spend the majority of their days sheltered within rock piles or crevices between the rocks of the sandstone outcrops they call home. After dark these animals move from their rocky habitats into the trees nearby, where they feed. Rock ringtail possums are secretive and avoid contact and confrontation. They are primarily terrestrial, moving into the trees only to feed. This distinguishes them from their close, mostly arboreal relatives .

• Key Behaviors
• scansorial
• terricolous
• nocturnal nocturnal
• motile motile
• sedentary sedentary
• social social

Home Range

Both sexes have about the same home range size. Average home range is 0.9 hectares, with home ranges ranging in size from 0.5 to 1.2 hectares. The average density in these home ranges is 0.4 possums per hectare.

Communication and Perception

Rock ringtail possums use chemical signals to communicate most extensively. Adult possums have an important scent gland on the chest region and males have a 2 cm diameter paracloacal gland. They maintain scent posts that are visited commonly. These scent posts develop a thick, lacquer-like coating. Rock ringtail possums use both urine and feces to mark these areas. These possums are also thought to mark tree branches using their paracloacal gland. Rock ringtail possums have been observed striking their tails against rocks, possibly as a form of communication. The species also is able to make grunts and growls that serve as auditory communication.

• Communication Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

• Other Communication Modes
• scent marks scent marks

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Rock ringtail possums feed in trees, they commonly feed within 100 meters of their rocky outcrop homes. This species eats leaves, fruit, blossoms, flowers, and occasionally feed on termites. THe blossoms of Darwin woollybutt, Eucalyptus miniata , and Darwin stringybark are all eaten by rock ringtail possums. Fruit is eaten from the following species: Zyziphus oenoplia , Vitex glabrata , Terminalia fernandiana , and Owenia vernicosa . Leaves eaten include: Flagelleria indica , Pouteria sericea , and vine reedcane.

• Primary Diet
• herbivore herbivore
  • folivore folivore
  • frugivore frugivore

• Animal Foods
• insects

• Plant Foods
• leaves
• fruit
• flowers

Predation

In order to avoid predations, rock ringtail possums spend a large amount of time participating in sentinel behavior. They will perch on branches or ledges and scan the area for danger. Rock ringtail possums will flee from predators to their more familiar rocky habitats where they will hide in rock crevices. When confronted they may make a low growl. Rock ringtail possums also beat their tails vigorously against tree branches, causing the entire tree to shake in order to attempt to deter predators and to warn others. Potential predators of rock ringtail possums include dingos, owls, quolls, feral cats and dogs, olive pythons, Oenpelli rock pythons, and humans.

Ecosystem Roles

Rock ringtail possums may disperse seeds through their fruit eating habits. They may also influence termite populations and act as prey for regional predators.

• Ecosystem Impact
• disperses seeds

Economic Importance for Humans: Positive

Aboriginal peoples of the area used to capture this species. They utilized the animal both for its fur and as a food source. Rock ringtail possums are also important in education and research.

• Positive Impacts
• food food
• body parts are source of valuable material
• research and education

Economic Importance for Humans: Negative

Petropseudes dahli has likely been affected by human induced habitat fragmentation and its numbers have decreased significantly. The species is listed as a priority species in western Australia and management efforts may affect forestry management and development practice.

Conservation Status

Petropseudes dahli is listed as priority species in Western Australia.

Other Comments

Petropseudes dahli mothers may actually allow her young to move from branch to branch by using her body as a bridge. This has never been seen in another possum. This species also exhibits the uncommon habit of embracing their young, which is only seen in apes. They are also the only marsupial ever seen utilizing termite mounds.

Additional Links

Encyclopedia of Life

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Robert Stroede (author), University of Wisconsin-Stevens Point, Chris Yahnke (editor, instructor), University of Wisconsin-Stevens Point.

References

Australian Wildlife Conservancy, 2006. "Australian Wildlife Conservancy" (On-line). Threatened Wildlife List: Rock ringtail possum Petropseudes dahli . Accessed November 29, 2006 at http://www.australianwildlife.org/threatenedwildlifelist.asp?WID=617 .

Collett, 1995. Rock Ringtail Possum. Pp. 242-243 in Mammals of Australia , Vol. Volume 1, Edition 2 Edition. Chatswood, New South Wales: Reed Books.

Crowe, O., I. Hume. 1997. Morphology and Function of the Gastrointestinal Tract of Australian Folivorous Possums. Australian Journal of Zoology , Volume 45/ Issue 4: 357-368.

Keast, A. 1968. The Quarterly Review of Biology; Evolution of Mammals on Southern Continents, IV. Austrailian Mammals:Zoogeography and Evolution. Austrailian Mammals , Vol. 43/ No. 4: 373 - 405.

Martin, S. 2002. Declining mammals of the savannas. Tropical Topics , No. 75/October 2002: 1-8.

McKay, G. 1989. Family Petauridae. Pp. 1-23 in Fauna of Australia , Vol. Vol 1, B Edition. Canberra: Austrailian Government Publishing.

McKenzie, N. 1981. Mammals of the Phanerozoic South-West Kimberley, Western Australia: Biogeography and Recent Changes. Journal of Biogeography , Vol. 8/ No. 4: 263-280. Accessed November 29, 2006 at http://links.jstor.org/sici?sici=0305-0220%28198107%298%3A4%3C263%3AMOTPSK%3E2.0.CO%3B2-F .

Runice, M. 2000. Adventures at Possum Rock. Nature Australia , Vol 26/ No 8: 30-45.

Runice, M. 2000. Biparental care and obligate monogamy in the rock-haunting possum, Petropseudes dahli , from tropical Australia. Animal Behaviour , Vol. 59/Part 5: 1001 - 1008.

Runice, M. 1999. Movements, dens and feeding behaviour of the tropical scaly-tailed possum( Wyulda squamicaudata ). Wildlife Research , Vol. 26/Issue 3: 367-373.