The quokkas of Rottnest Island
The quokka is possibly the most well-known animal on Rottnest Island. It was first observed by a European in 1658 when the Dutchman, Volkersen, wrote that it resembled an Asian civet cat, but with brown hair. In 1696 de Vlamingh described the quokka as "a kind of rat as big as a common cat". He named the Island 'Rotte nest' (meaning 'rat's nest') and the name of the Island was eventually adapted to 'Rottnest'.
The name "quokka" comes from the name given to the animal by the Aboriginal people living in the Augusta and King George Sound area of the south-west of Western Australia. A marsupial the size of a hare or domestic cat, the quokka is the sole representative of the genus Setonix. As with other marsupials, such as the kangaroo, wallaby, wallaroo, bettong and potoroo, the females suckle their young in a pouch. They give birth in late summer, after a gestation period of twenty-seven days, and the young quokka remains in the pouch until August or September, and is then suckled for a further two months. The quokka reaches maturity at about one-and-a-half to two years of age, and lives to be ten years old.
Quokkas are generally nocturnal and spend most of the day sleeping and resting under shady bushes and dense vegetation. On the island they can be seen opportunistically feeding during the day. The quokka’s diet consists of grass, leaves, seeds and roots. They swallow their food without chewing and later regurgitate the cud which they chew on. This is a very effective way to ensure that all the moisture and nutrients is obtained from the dry nutrient deficient vegetation available on the island. Quokkas need very little water and can go months without drinking from a direct water source. Eating ‘human food’ can be very detrimental to the quokkas health causing them to be dehydrated and malnourished.
When Europeans first settled in Western Australia the quokka was widespread in many parts of the south-west as well as on Rottnest, Bald Island and in the vicinity of Perth, probably as far north as Moore River. With the introduction of predators such as foxes and loss of habitat, their population on the mainland dramatically diminished. Due to the lack of predators and the availability of food on Rottnest Island, population numbers have soared to approximately 12,000. This has put substantial pressure on the existing vegetation, particularly Rottnest Island tea tree and Rottnest Island pine seedlings which are favoured meals for the quokka. Despite these large numbers, populations are extremely responsive to disturbance and numbers can decrease significantly in harsh seasons.
It is important for visitors to refrain from feeding quokkas and other fauna on Rottnest Island. Quokkas may become very ill as a result of eating unsuitable food such as bread, chips and meat. It is also equally important not to provide quokkas with an artificial water supply as it has the potential to alter natural behavior and can also cause toxicity within the quokkas body leading to death. Rottnest Island Rangers may issue infringements to people who feed quokkas.