Quokka

The Quokka is the only mammal which is native to Rottnest Island and can be found almost everywhere on the Island. It is mainly nocturnal. This means that it is mostly active at night, preferring to rest or sleep in the shade during the day. The Quokka bounds and hops along the ground although it can climb trees if it needs to. It will sit on its hind legs to look around and will also use its front paws to search for and pick up food.

## Description

A quokka weighs 2.5 to 5.0 kg (5.5 to 11.0 lb) and is 40 to 54 cm (16 to 21 in) long with a 25-to-30 cm-long (9.8-to-11.8 in) tail, which is quite short for a macropod. It has a stocky build, well developed hind legs, rounded ears, and a short, broad head. Its musculoskeletal system was originally adapted for terrestrial bipedal saltation, but over its evolution, its system has been built for arboreal locomotion. Although looking rather like a very small kangaroo, it can climb small trees and shrubs up to 1.5 metres (4 ft 11 in). Its coarse fur is a grizzled brown colour, fading to buff underneath. The quokka is known to live for an average of 10 years.

Quokkas have a promiscuous mating system. After a month of gestation, females give birth to a single baby called a joey. Females can give birth twice a year and produce about 17 joeys during their lifespan. The joey lives in its mother's pouch for six months. Once it leaves the pouch, the joey relies on its mother for milk for two more months and is fully weaned around 8 months after birth. Females sexually mature after roughly 18 months. When a female quokka with a joey in her pouch is pursued by a predator, she may drop her baby onto the ground; the joey produces noises, which may serve to attract the predator's attention, while the mother escapes.

## Diet

Like most macropods, quokkas eat many types of vegetation, including grasses and leaves. A study found that *Guichenotia ledifolia*, a small shrub species of the family Malvaceae, is one of the quokka's favoured foods. Rottnest Island visitors are urged to never feed quokkas, in part because eating "human food" can cause dehydration and malnourishment, both of which are detrimental to the quokka's health. Despite the relative lack of fresh water on Rottnest Island, quokkas do have high water requirements, which they satisfy mostly through eating vegetation. On the mainland, quokkas only live in areas that have 600 mm (24 in) or more of rain per year.

## Population

At the time of colonial settlement, the quokka was widespread and abundant, with its distribution encompassing an area of about 41,200 km2 (15,900 sq mi) of south-west Western Australia, including the two offshore islands, Bald and Rottnest. By 1992, following extensive population declines in the 20th century, the quokka's distribution on the mainland had been reduced by more than 50% to an area of about 17,800 km2 (6,900 sq mi).

Despite being numerous on the small, offshore islands, the quokka is classified as vulnerable. On the mainland, where it is threatened by introduced predatory species such as foxes, cats, and dogs, it requires dense ground cover for refuge. Clearfell logging, agricultural development, and housing expansion have reduced that habitat, contributing to the decline of the species, as has the clearing and burning of the remaining swamplands. Moreover, quokkas usually have a litter size of one and successfully rear one young each year. Although they are constantly mating, usually one day after the young are born, the small litter size, along with the restricted space and threatening predators, contributes to the scarcity of the species on the mainland.

An estimated 4,000 quokkas occur on the mainland, with nearly all mainland populations being groups of fewer than 50, although one declining group of over 700 occurs in the southern forest between Nannup and Denmark. In 2015, an extensive bushfire near Northcliffe nearly eradicated one of the local mainland populations, with an estimated 90% of the 500 quokkas dying.

In 2007, the quokka population on Rottnest Island was estimated at between 8,000 and 12,000. Snakes are the quokka's only predator on the island. The population on smaller Bald Island, where the quokka has no predators, is 600–1,000. At the end of summer and into autumn, a seasonal decline of quokkas occurs on Rottnest Island, where loss of vegetation and reduction of available surface water can lead to starvation.