The rock-haunting ringtail possum (''Petropseudes dahli''), also known as the rock ringtail possum, is a species of

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

n possum. It is found in rocky escarpments in the Kimberley,

Arnhem Land Arnhem Land is a historical region of the Northern Territory of Australia. It is located in the north-eastern corner of the territory and is around from the territorial capital, Darwin, Northern Territory, Darwin. In 1623, Dutch East India Compa ...

and

Gulf of Carpentaria The Gulf of Carpentaria is a sea off the northern coast of Australia. It is enclosed on three sides by northern Australia and bounded on the north by the eastern Arafura Sea, which separates Australia and New Guinea. The northern boundary ...

across

Western Australia Western Australia (WA) is the westernmost state of Australia. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to the south, the Northern Territory to the north-east, and South Australia to the south-east. Western Aust ...

and

Northern Territory The Northern Territory (abbreviated as NT; known formally as the Northern Territory of Australia and informally as the Territory) is an states and territories of Australia, Australian internal territory in the central and central-northern regi ...

and just passing the

Queensland Queensland ( , commonly abbreviated as Qld) is a States and territories of Australia, state in northeastern Australia, and is the second-largest and third-most populous state in Australia. It is bordered by the Northern Territory, South Austr ...

border. It is also found on Groote Eylandt. According to some authorities, it is the only species in the genus ''Petropseudes'', but other authorities place it among the members of the genus '' Pseudochirops''. The rock-haunting ringtail possum has one of the shortest tails of all ringtail possums, and at its end it is hairless and scaly. It lives in small groups and is mainly herbivorous. It has a stocky build and is mostly grey in colour.

Description

The rock-haunting ringtail possum is almost the size of a small

rabbit Rabbits are small mammals in the family Leporidae (which also includes the hares), which is in the order Lagomorpha (which also includes pikas). They are familiar throughout the world as a small herbivore, a prey animal, a domesticated ...

. It is grey to reddish-grey in colour on the back, while its underside is a light cream colour. It has white hair patches underneath its small, round ears and both above and below the eyes.ADW: Petropseudes dahli: Information
/ref> A mid-dorsal stripe runs from the crown of the head to the middle of the back. Like other possums, it has a prehensile tail, adapted for grasping especially by wrapping around. However, the tail is unique in its appearance compared to that of other possums as it is covered with fur only halfway down. Males are 33.4 to 37.5 cm long while females are generally bigger and range from 34.9 to 38.3 cm in length and weigh between 1,280 and 2,000 grams. Another uncommon feature in the appearance of this species is that it has vertical pupils.

Ecology

The rock-haunting ringtail possum disperses seeds through its fruit eating habits. It also influences termite populations and acts as prey for regional predators. The rock-haunting ringtail possum has been affected by human induced

habitat fragmentation Habitat fragmentation describes the emergence of discontinuities (fragmentation) in an organism's preferred environment (habitat), causing population fragmentation and ecosystem decay. Causes of habitat fragmentation include geological proces ...

and hence, its numbers have decreased significantly. The species is listed as a priority species in Western Australia.

Habitat

The rock-haunting ringtail possum lives exclusively in rocky outcrops and prefers areas with large boulders and deeply fissured rock. It uses the crevices to hide by just sticking its head into the crevice with the body exposed. It is strictly

nocturnal Nocturnality is a ethology, behavior in some non-human animals characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnality, diurnal meaning the opposite. Nocturnal creatur ...

; it only moves out of its sheltered rock crevices to climbing trees to feed at night. It does not make a nest and has been observed occasionally to be sleeping in well protected rock ledges during the day. This suggests a high level of adaptation to a terrestrial existence. Indicators of a reduction in arboreal adaptation are shorter legs, shorter claws, shorter tail and a slightly longer snout.

Diet

The rock-haunting ringtail possum eats

fruit In botany, a fruit is the seed-bearing structure in flowering plants (angiosperms) that is formed from the ovary after flowering. Fruits are the means by which angiosperms disseminate their seeds. Edible fruits in particular have long propaga ...

flower Flowers, also known as blooms and blossoms, are the reproductive structures of flowering plants ( angiosperms). Typically, they are structured in four circular levels, called whorls, around the end of a stalk. These whorls include: calyx, m ...

s and

leaves A leaf (: leaves) is a principal appendage of the stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, ...

of a variety of trees found near its habitat and occasionally feeds on

termite Termites are a group of detritivore, detritophagous Eusociality, eusocial cockroaches which consume a variety of Detritus, decaying plant material, generally in the form of wood, Plant litter, leaf litter, and Humus, soil humus. They are dist ...

s. It usually stays close to the rocks while feeding but has been found as far as 100m from the nearest outcrop. Most common of the blossoms it eats are of Darwin Woollybutt ('' Eucalyptus miniata'') and Darwin Stringybark ('' Eucalyptus tetrodonta''). Its major fruit intake is from '' Zyziphus oenoplia'', '' Vitex glabrata'', Billy Goat Plum ('' Terminalia ferdinandiana''), and '' Owenia vernicosa''. Leaves eaten include '' Flagelleria indica'', '' Sersalisia sericea'', and vine reedcane.

Known predators

Some known predators of the rock-haunting ringtail possum are the Dingo (''Canis lupus dingo''), the Oenpelli Python (''Morelia oenpelliensis''), the Olive Python (''Liasis olivaceous''), quolls (''Dasyurus'' spp.), owls (Strigiformes), feral cats (''Felis catus''),

red fox The red fox (''Vulpes vulpes'') is the largest of the true foxes and one of the most widely distributed members of the order Carnivora, being present across the entire Northern Hemisphere including most of North America, Europe and Asia, plus ...

es ''(Vulpes vulpes)'', domestic dogs (''Canis lupus familiaris'') and

human Humans (''Homo sapiens'') or modern humans are the most common and widespread species of primate, and the last surviving species of the genus ''Homo''. They are Hominidae, great apes characterized by their Prehistory of nakedness and clothing ...

s (''Homo sapiens''). The rock-haunting ringtail possum spends a large amount of time participating in sentinel behaviour to avoid predators. It perches on branches or ledges and scans the area for danger. In an attempt to deter predators and to warn others, this possum beats its tail against tree branches vigorously causing the entire tree to shake.

Lifestyle

Of all the Australian possums, the rock-haunting ringtail possum lives in the most tightly knit family groups. Adults and their young will stay within 2–3 metres of each other throughout the night. The family groups are generally made up of about 4 individuals, although group sizes of 2 to 10 individuals have been reported. The possum spends most of its time sheltered within rock piles or crevices. After dark it moves from its rocky home into the nearby trees where it feeds. This possum is secretive, difficult to trap and avoids contact and confrontation as far as possible. It is primarily terrestrial, moving into the trees only to feed. This distinguishes it from its close, mostly

arboreal Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally (scansorial), but others are exclusively arboreal. The hab ...

relatives. Its eye-shine is very bright in a spotlight but unlike most possums, it does not freeze when caught in a beam of light. Instead, it retreats to its rock shelter or crevices where it hides with its head in the crevice but its body exposed.

Reproduction

There appears to be no particular season for breeding. However, females with a large young in the pouch and a young on the back have been seen in March, July, August and September. Although the

gestation Gestation is the period of development during the carrying of an embryo, and later fetus, inside viviparous animals (the embryo develops within the parent). It is typical for mammals, but also occurs for some non-mammals. Mammals during pregn ...

period information is not available for the species, it is known that close relatives have gestation periods from 16 to 30 days. The new offspring spends its first five weeks in the female's large pouch which has two teats. The parents usually carry the new offspring on their back after they have left the mother's pouch. Caring for the young is divided nearly equally among the parents. The parents are assisted in raising the offspring by the previous offspring who commonly stay with the family unit. The parents practice protective behaviours such as spend time watching for predators, tail beating, and vocalizing and marshaling the young to keep them relatively close.

Home range and obligate monogamy

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. Females live with one male in their home range, which are commonly marked by scent posts. To scent-mark, the rock-haunting ringtail possum rubs or presses their cloacal-caudal region or chest against the surface. While the possum also marked rock ledges and trees within its home ranges, scent marking was most vigorous around den sites. The rock-haunting ringtail possum is one of few obligate monogamous marsupial species. A consistent characteristic of obligate monogamy displayed by this species is the existence of cohesive and persistent pair bonds with mutual or asymmetrical attraction between adults. Both sexes of this species maintain strong pair bonds, as shown by the wide array of maintenance behaviours, which is a measure of bond 'strength'. However, males maintained the pair bond at a higher rate than females. Both sexes shared the decision-making process in terms of changing group activity. Presence of long-lasting bonds between parents and young seen in the family of this species is another attribute of obligate monogamy. Both sexes of the rock-haunting ringtail possum showed substantial long-term care of offspring. An unusual interaction observed between parents and young were the embrace by adult males and the bridge formation. Both sexes embrace young, whereas only females engage in bridge formation. The mother allows her young to move from branch to branch by using her body as a bridge. This has never been seen in another possum. Embracing is a way for the adults to know the stage of maturation of the offspring. A third feature of obligate monogamy shown by the Rock-haunting Ringtail Possum is the rearing of younger siblings by juveniles.

Communication

The rock-haunting ringtail possum mostly uses scent to communicate. Adult possums have a distinct gland on the chest and males have a paracloacal gland which is about 2 cm in diameter. The possum maintains scent posts that are visited commonly. The rock-haunting ringtail possum uses both urine and faeces to mark these areas. This possum is also thought to mark tree branches using its paracloacal gland. The rock-haunting ringtail possum has been observed striking its tail against rocks, possibly as a form of communication. The species also is able to make quiet screeches and grunts that serve as auditory communication.

In Aboriginal language and culture

The Kunwinjku of Western Arnhem Land hunted ngingma, as they call this possum by placing sugar bag (bush honey) on a rock. Attracted to the bait the animal was then speared. Another name for this species in Bininj Kunwok is djorrkkun. Knut Dahl, who caught the specimen from which the specimen from which the species was described, called it a wogoit, the name the local tribe used for the animal.

References

{{Taxonbar, from=Q1404175 Possums Mammals of Western Australia Mammals of the Northern Territory Mammals described in 1895 Taxa named by Robert Collett