About Pseudocheirus peregrinus (Boddaert, 1785)
Adult common ringtail possums (Pseudocheirus peregrinus) weigh between 550 and 1,100 g (19 and 39 oz), with a body length of 30–35 cm (12–14 in) not including the tail, which is roughly the same length as the body. Their fur is grey or black, with white patches behind the eyes and usually a cream-coloured belly. They have a long prehensile tail that typically has a distinctive white tip making up over 25% of the tail's total length. Their back feet are syndactyl, an adaptation that helps them climb, and their molars have sharp, pointed cusps. The common ringtail possum is distributed along the east coast of Australia, Tasmania, and part of southwestern Australia. It generally inhabits temperate and tropical environments, and is rare in drier regions. It prefers dense brush forests, particularly eucalyptus forests. The common ringtail possum and its relatives fill a range of ecological niches similar to those occupied by lemurs, monkeys, squirrels, and bushbabies in comparable forests on other continents. It is less prolific and less widespread than the common brushtail possum. As a marsupial, the common ringtail possum carries and raises its developing young in a pouch. Mating season occurs anywhere between April and December depending on the region, with most young born between May and July. The species has an oestrous cycle of 28 days, and is both polyoestrous and polyovular. If a female loses her litter prematurely, she can return to oestrous and produce a replacement litter in October if conditions are suitable. The average litter size is two, though triplets occur very rarely. Common ringtail possum young grow relatively slowly, because the mother's milk is dilute with low lipid content. Like other marsupials, the composition of common ringtail possum milk changes throughout lactation. During the second lactation phase, after the young first emerge from the pouch, they begin eating more solid foods. At this stage, carbohydrate concentration in the milk falls, while protein and lipid concentrations reach their highest levels. The long lactation period gives young more time to learn skills in the communal nest, and to practice climbing and foraging in trees. Young common ringtail possums first gain the ability to vocalise and open their eyes between 90 and 106 days after birth. They leave their mother's pouch at 120–130 days old, but lactation usually continues until 180–220 days after birth, and sometimes ends as early as 145 days. Both sexes reach sexual maturity during the first mating season after their birth.
