The family Pseudocheiridae
The woylie or brush-tailed bettong (Bettongia penicillata)
Pseudocheiridae is a family of arboreal marsupials containing 17 extant species of ringtailed possums and close relatives. They are found in forested areas and shrublands throughout Australia and New Guinea.
Description and special features
Pseudocheiridae are a family of marsupial mammals of the order Diprotodontia containing approximately 17 species of ring-tailed possums and related forms. Until recently, these animals belonged to the family Pettauridae (Petauridae). Pseudocheiridae are small moults (weighing 0.5-2 kg) with a strong, sticky tail. Their limbs are five-toed, grasping; the first and second toes of the forelimbs are opposite the others. The pouch of the Pseudocheiridae is well developed and opens forward. One member of the family, the Giant Pseudocheirid (Petauroides volans), has a sliding skin membrane similar to that of marsupial voles, which, however, does not extend from the wrists but from the elbows to the ankles.
Habitat
Pseudocheiridae are common in Australia and New Guinea. They lead a mainly arboreal lifestyle, feeding mostly on vegetation and mainly on leaves.
Classification
The listing for extant species is based on The Third edition of Wilson & Reeder's Mammal Species of the World (2005), except where the Mammal Diversity Database and IUCN agree on a change. The 18 living species of pseudocheirid possum are grouped into three subfamilies and six genera.
- †Pildra;
- †Paljara;
- †Marlu;
- †Pseudokoala;
- Subfamily Hemibelideinae:
- Genus Hemibelideus:
- Lemur-like ringtail possum, Hemibelideus lemuroides;
- Genus Petauroides:
- Southern greater glider, Petauroides volans;
- Subfamily Pseudocheirinae:
- Genus Petropseudes:
- Rock-haunting ringtail possum, Petropseudes dahli;
- Genus Pseudocheirus:
- Common ringtail possum, Pseudocheirus peregrinus;
- Western ringtail possum, Pseudocheirus occidentalis;
- Genus Pseudochirulus:
- Lowland ringtail possum, Pseudochirulus canescens;
- Weyland ringtail possum, Pseudochirulus caroli;
- Cinereus ringtail possum, Pseudochirulus cinereus;
- Painted ringtail possum, Pseudochirulus forbesi;
- Herbert River ringtail possum, Pseudochirulus herbertensis;
- Masked ringtail possum, Pseudochirulus larvatus;
- Pygmy ringtail possum, Pseudochirulus mayeri;
- Vogelkop ringtail possum, Pseudochirulus schlegeli;
- Subfamily Pseudochiropsinae:
- Genus Pseudochirops:
- D'Albertis' ringtail possum, Pseudochirops albertisii;
- Green ringtail possum, Pseudochirops archeri;
- Plush-coated ringtail possum, Pseudochirops corinnae;
- Reclusive ringtail possum, Pseudochirops coronatus;
- Coppery ringtail possum, Pseudochirops cupreus;
- †Pseudochirops winteri.
The woylie or brush-tailed bettong (Bettongia penicillata)
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, fruits and sap. 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 caecotrophy and is similar to that seen in rabbits.
Taxonomy
The common ringtail possum is currently classified as one of the two 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:
- Pseudocheirus peregrinus pereginus, the type subspecies based on a collection made at Endeavour River;
- Pseudocheirus peregrinus convolutor, (Eastern ringtail possum or Southeastern ringtail possum);
- Pseudocheirus peregrinus pulcher, (Rufous ringtail possum);
- Pseudocheirus occidentalis (Ngwayir, or the Western ringtail possum), found in the south west of Australia, used to be considered a subspecies of Pseudocheirus peregrinus; however, it is now formally considered a separate species.
Appearance and peculiarities
Pseudocheirus peregrinus is a species of marsupial diprotodon of the family Pseudocheiridae native to Australia.
Pseudocheirus peregrinus feeds on the leaves of a wide variety of plants, both native and introduced, as well as their flowers and fruits. During the day, these animals usually rest in their nests. During this time they usually eat their own excrement (this strange behaviour, characteristic of many vegetarian animals, is called coprophagy).
This small animal weighs between 500 and 1,100 g and is about 30-35 cm long, with a tail of the same length.
It is mainly grey in colour, with only cream-coloured stripes under the eyes and a light-coloured belly. It has a long prehensile tail with a distinctive white tip about 25% of the total tail size. Its hind feet are syndactylous, which makes it easier for it to climb trees. The conical teeth of Pseudocheirus peregrinus are very sharp.
Metabolism
The re-ingestion of caecal content also serves to maintain the ringtail possum's energy balance. Ringtail possums gain much of their gross energy from reingestion. The common ringtail possum has a daily maintenance nitrogen requirement (MNR) of 290 mg N/kg0.75. Common ringtail possums gain much of their MNR from consuming their nitrogen-rich caecal pellets. They would have to gain 620 mg N/kg0.75 otherwise. The ringtail possum recycles 96% of its liver's urea, which is then transferred into the caecum and made into bacterial protein. Only re-ingestion makes this effective and the bacterial protein must be digested in the stomach and the amino acids subsequently absorbed in the small intestine. This recycling also allows the possum to conserve water and urinate less. Reingestion allows the possum to live on low nitrogen eucalyptus leaves which is particularly important during late lactation. It has been found that at higher temperatures, the common ringtail possum consumes less food due to a limited ability to metabolize toxins found in their diet. Because 55% of their water intake comes from the leaves and foliage they consume, their metabolic rate must remain low and stable while facing water loss. In response to this challenge, common ringtail possums can control their body temperature and conserve water by using facultative hyperthermia to temporarily raise their internal body temperature, ranging from 29 to 39 °C (84 to 102 °F).
Distribution and nutrition
Pseudocheirus peregrinus is common on the east coast of Australia, southwest Australia and Tasmania. They are nocturnal, climb trees very well and rarely come down to land. They live in humid tropical rainforests, and are particularly fond of eucalyptus forests because they like to eat the leaves. Although Pseudocheirus peregrinus selects the youngest leaves, they are still difficult to digest because of the large amount of tannin. Even after the pieces of leaf torn by the sharp teeth remain in the appendix for about 70 hours, they are still incompletely digested. Unlike the koala, the semi-digested contents of the blind appendix can be reintroduced into the stomach, providing the animal with additional nutrients. Interestingly, Pseudocheirus peregrinus produce liquid excreta during the day and solid excreta at night during sleep.
Behaviour
Pseudocheirus peregrinus build their nests in tree branches or use prepared sleeping holes. Often, adult males and females and their young of different ages make communal nests in which the whole family roosts. There may be several such nests and they are located in different parts of the forest. Pseudocheirus peregrinus are territorial and chase away strangers approaching their nests. They are very attached to their territories. For example, in an experiment in which Pseudocheirus peregrinus was removed from a patch of forest, it remained unoccupied for two years.
Reproduction and growth
The common ringtail possum carries its young in a pouch, where it develops. Depending on the area, the mating season can take place anywhere between April and December. The majority of the young are born between May and July. The oestrous cycle of ringtail possum lasts 28 days. It is both polyoestrous and polyovular. If a female prematurely loses her litter, she can return to oestrous and produce a second litter in October as a replacement if conditions are right. The average litter is two, although there are very occasionally triplets. Common ringtail possum young tend to grow relatively slowly due to dilute milk with low lipid levels that is provided to the young. As with other marsupials, the common ringtail possum's milk changes through lactation. During the second phase of lactation, more solid foods are eaten, especially when the young first emerges from the pouch. During this time, the concentration of carbohydrates fall, while those of proteins and lipids reach their highest. The long lactation of the ringtail possums may give the young more time to learn skills in the communal nest as well as to climb and forage in the trees.
The young are first able to vocalise and open their eyes between 90 and 106 days of age. They leave their mother's pouch at 120–130 days. However, lactation usually continues until 180–220 days after birth but sometimes ends by 145 days. Both sexes become sexually mature in the first mating season after their birth.
Status
Common ringtail possum populations severely declined during the 1950s. However, populations seem to have recovered in recent times. Because they are largely arboreal, common ringtail possums are particularly affected by deforestation in Australia. They are also heavily preyed upon by the introduced red fox. They are also hit by cars, or killed by snakes, cats and dogs in suburban areas.
