Quokka

The Quokka is one of the smallest wallabies. This marsupial has the ability to climb trees.

Identification

The Quokka, Setonix brachyurus, was described by early Dutch explorer, Willem de Vlamingh, 'as a kind of rat as big as a common cat'. His first sighting of the Quokka was on an island off the mouth of the Swan River. He named the island Rottenest ('rat nest') in honour of this sighting. The island is now known as Rottnest Island.

Essentially the Quokka looks very much like other wallabies.It has short, very coarse and thick grey-brown fur over most of the body with lighter parts underneath. Its facial features consist of a naked nose on a short, broad face with rounded furry ears.The tail is relatively short and mostly devoid of hair. In contrast, the hair on the feet extends to cover its claws.

Habitat

Mainland populations tend to be clustered around dense streamside vegetation but can also be found in shrubland and heath areas, particularly around swamps. Quokkas prefer a warm climate but are adapted to the seasonal variations on Rottnest Island. Here Quokkas occupy a wide range of semi-arid areas.

This tendency points to the Quokka being a habitat specialist with a preference for areas that have been burned in the last ten years.They are however, present on Bald Island even though there has been a low frequency of fires there. Their success on Bald Island is probably due to their finding suitable food sources and the lack of predators.

Distribution

Restricted to the south west region of Western Australia, Quokkas are found on the mainland as well as on Rottnest Island (near Perth) and Bald Island (near Albany). Their presence on the mainland has declined severely in the twentieth century to the extent that they are only found in small groups in bushland surrounding Perth including Two Peoples Bay Nature Reserve, Torndirrup National Park, Mt Manypeaks National Park and the Stirling Range National Park.

Feeding and diet

Quokkas are plant eaters or herbivores.In fact they can be described as browsing herbivores who favour various grasses and leaves, the most popular being plants from the Thomasia species. The seasonal variation on the availability of food sources is linked to the fresh growth associated with fires. Quokkas show a distinct preference for new young growth.

On Rottnest Island their diet is primarily succulents and to a lesser extent the leaves of wattles.

Other behaviours and adaptations

Quokkas are most active at night feeding alone or in small bands. However, they can survive for long periods without food or water.During the day they will shelter in areas of dense vegetation.Among the dense vegetation, Quokkas will create paths and trails for use as runways for feeding or escaping predators.

Their movements resemble a bounding gait interspersed with hopping. They are able to climb trees to reach a food source.

Quokkas are known to suffer from muscular dystrophy and have been employed in medical research in that area.

Life history cycle

On the mainland, the Quokka appears to be able to breed all year round but the breeding season on Rottnest Island is shorter (from January to August). Female Quokkas give birth to a single young about a month after mating. The young will remain in the pouch for about six months. After the joey leaves the pouch it will continue to feed at its mother's teats for an extra two months or so. Joeys are usually weaned by eight months of age.

Breeding behaviours

Quokkas,on average, can live for about ten years. They are able to breed from about eighteen months of age. On the mainland, female Quokkas are able to produce about seventeen offspring over a lifetime, with two joeys being born each year. However on Rottnest Island, with a shorter breeding season,Quokkas usually only give birth to one offspring per year.

Conservation status

The Quokka is listed as vulnerable.They are most vulnerable on the mainland where their numbers have suffered with the arrival of the Dingo some 4,000 years ago and more recently the European Red Fox, Vulpes vulpes, in the 1930s. The populations found on Rottnest are less susceptible to decline as the island is fox free. Generally speaking, human impact has also had an effect on Quokka numbers. Clearing for agricultiral development, the spread of housing and logging have contributed to this as well as recreational activities such as camping, and control burns before the bushfire season.

Some action has been taken to reduce Red Fox numbers and this has contributed to some population recovery.

References

• Cronin Leonard: Cronin's Key Guide to Australian Wildlife. Allen & Unwin 2007.
• Menkhorst P, Knight F: A Field Guide to the Mammals of Australia. Oxford University Press 2004.
• Strahan R: Mammals of Australia. Reed New Holland 1995.
• Strahan R: Encyclopedia of Australian Mammals. Angus & Robertson 1992.
• Strahan R: Photographic Guide to the Mammals of Australia. New Holland Publishing. 1995.
• Taylor J. Mary: The Oxford Guide to the Mammals of Australia. Oxford University Press 1984.