| Common ringtail possum[1] | |
|---|---|
| Conservation status | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Infraclass: | Marsupialia |
| Order: | Diprotodontia |
| Family: | Pseudocheiridae |
| Subfamily: | Pseudocheirinae |
| Genus: | Pseudocheirus |
| Species: | P. peregrinus |
| Binomial name | |
| Pseudocheirus peregrinus (Boddaert, 1785) |
|
| Common ringtail possum range (except western ringtail possum (Pseudocheirus peregrinus occidentalis) range) (blue — native, red — introduced) | |
The common ringtail possum (Pseudocheirus peregrinus, Greek for "false hand" and Latin for "pilgrim" or "alien") is an Australian marsupial. It lives in a variety of habitats and eats a variety of leaves of both native and introduced plants, as well as flowers and fruits. These dietary factors have, over time, aided burgeoning introduced (pest) populations in New Zealand. This possum also consumes a special type of faeces that is produced during the daytime when it is resting in a nest. This behaviour is called coprophagia and is similar to that seen in rabbits.
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The common ringtail possum is currently classified as the only living species in the genus Pseudocheirus; the species of Pseudochirulus and other ringtail genera were formerly also classified in Pseudocheirus. Several subspecies have been described, such as the Western Australian Pseudocheirus peregrinus occidentalis, but the entire population may be a species complex.[1] The arrangement as the only extant species of Pseudocheirus is:[1]
The common ringtail possum weighs between 550 and 1100 g. It has grey fur with white patches behind the eyes and usually a cream coloured belly. It has a long prehensile tail which normally displays a distinctive white tip over 25% of its length. The back feet are syndactyl which helps it to climb. The molar teeth of the ringtail possum is similar to that of the koala and the greater glider with the four major cusps being shaped into crescentic blades.[4]
Common ringtail possums are found along the eastern coastline of Australia, Tasmania, and the south-western corner of western Australia.[5] They generally live in temperature and tropical environments and are rare in drier areas. Ringtail possums prefer forests of dense brush.[5] The common ringtail possum and its relatives occupy a range of niches in a matter similar of lemurs, monkeys, squirrels, and bushbabies in similar forests on other continents.[6]
The common ringtail possum prefers to feed on Eucalyptus foliage and the highest densities of ringtail possums are found in areas where Eucalyptus are found.[4] However, ringtail possums will eat foliage, flowers and fruits from other species of trees and shrubs from the lower levels of the forest.[7] When foraging, ringtail possums prefer young leaves over old ones. One study found that young possums emerge from the pouches when the flush of plant growth and the flowering and fruiting of the tea-tree, Leptospermum.[8] Young eucalypt foliage have a higher concentration of nitrogen and lower cell-wall concentration than older leaves and the higher concentrations of tannins make the protein less available.[9] When feeding, the possum’s teeth cuts the leaves in very small pieces. Much like the koala and the greater glider, the common ringtail possum has a large caecum which is where the fine coarse particles that are separated.[4] These particles are retained in the caecum for up to 70 hours.[4] Here, massive colonies of micro-organisms attach to the tissue components and cause partial digestion of cells walls and tanned cytoplasts.[10]
What distinguishes the system of the digestive system of the common ringtail possum from that of the koala and the greater glider, is the caecal content is taken directly back to the stomach, where they go on a second passage through the gut. Because of this, the ringtail possum gains far greater access to protein and the energy products of bacterial fermentation in its caecum.[4] This is also done by lagomorphs like rabbits and pikas. Hard faeces are produced during the night while foraging and are not eaten, while soft faeces are produced during the day while resting have been recorded being taken directly from the cloaca.[11]
The re-ingestion of caecal content also serves to maintain the ringtail possum’s energy balance. Ringtail possum seem to prefer Eucalyptus andrewii over other species and feed almost exclusively on it in captivity.[12] When consuming these plants, ringtail possums gain the much of their gross energy from reingestion.[12] The the common ringtail possum has a daily maintenance nitrogen requirement (MNR) of 290 mg N/kg0.75, similarly to the koala but is half the requirements of the greater glider. Still, common ringtail possums gain much of their MNR from consuming their nitrogen-rich caecal pellets. A ringtail possum would need to obtain 620 620 mg N/kg0.75 if it did not have this additional access to metabolic nitrogen.[4] For the ringtail possum, 96% of the urea that is produced in the liver is recycled into the caecum and is then synthesised into bacterial protein from there. However, this is only useful with re-ingestion since the bacterial protein must be digested in the stomach and the amino acids in the small intestine.[4] By recycling urea, the ringtail possum also conserves water. Instead of being released as urine, some of the water is returned to the stomach in the caecal pellets. Ringtail possums get most of their water intake from the free water in the leaves they eat which is supplemented with drinking water.[4] Re-ingestion is thus important in water conservation and for feeding on Eucalyptus leaves which have a nitrogen content of only 1.1%.[4] It is particularly important during late lactation which requires 1.4 g of protein to be export each day in milk to support the growth of the young.[13]
Common ringtail possums are mostly nocturnal and are well adapted to arboreal life. They are rarely found on the ground and use their prehensile tail extensively.[5] They have been known to communicate with soft, high-pitched, and twittering calls.[14]
Common ringtail possums live a gregarious lifestyle that is centred around the communal nests. Ringtail possums build nests called greyer in the branches of trees or in large tree hollows. A communal is made up of an adult male with one or two adult females, their dependant offspring and immature offspring of the previous year.[7] A group of ringtail possums may build several greyer at different heights and localities. Ringtail possums are territorial and will drive anyway any strange conspecifics from their nests. A group has a strong attachment to their site. In one experiment, a group was removed from their territory and it was not recolonised for the next two years.[7] Ringtail possum nests tend to be more abundant in low scrub or areas regenerating after partial clearance and are less abundant in heavy timbered country with sparse under-story.[4] Greyers are an important element in the survival of the young after they relinquish their mother’s back. They also serve as a daytime refuge for adults.[4]
Common ringtail possums are marsupials, thus they carry their young in a pouch while they develop. Depending on the location in Australia, the mating season can take takes place anywhere between April and December.[5] The majority of the young are born between May and July. The ringtail possum has an estrous cycle lasting 28 days.[6] It is both polyestrous and polyovular. If a female prematurely loses her liter, she can return to oestrous and produce a second litter in October as a replacement if conditions are right.[4] The average number of young in a litter is two, although four young can be reared as the female has four teats in her pouch.[4] Usually two of the four nipples are functional at one time and pouch has a forward facing opening and.[5] Initial growth of the common ringtail possum young is generally slow. This slow growth occurs during the period when the weight of the female is at its lowest. The slow growth rate is due to the quality of the milk being providing to the young. As with other marsupials, the common ringtail possum’s milk changes through lactation.[15] In comparison with the milks of other marsupial species, ringtail possum milk is relatively dilute and low in lipid. During the second phase of lactation solids represent around 16% (w/w) and increases to 25% (w/w) when the young first emerges from the pouch.[15] During this time, concentration of carbohydrates declines while concentrations of protein and lipid peak.[15] The long lactation of the ringtail possums may provide the young the opportunity to learn skills in the communal nest and develop their ability to climb and forage in the trees.[4]
The young both open their eyes and are able to make clear vocalisations, between 90 and 106 days after birth,.[5] The young emerge from their mother's pouch 120–130 days after birth. However, lactation generally does not stop until 180–220 days after birth and sometimes ends as early as 145 days.[6] Both sexes become sexually mature in the first mating season after their birth.
Common ringtail possum populations severely declined during the 1950s. However, populations seem to have recovered in current times.[5] Because they are almost exclusively arboreal, common ringtail possums have loss a lot of habitat due to deforestation in Australia. Ringtail possums are vulnerable to being struck by cars, or hunted by cats and dogs in suburban areas.[5] This species do not adversely affect humans. Ringtail possums do not nest within homes or human structures and as such are not considered pests.[5]