Often termed as the happiest animal in the world, a Quokka is an Australian mammal found on the island of Rottnest and also other small areas of the Australian mainland. Quokka is a herbivore and may resemble a large rat even though they have a size of an average cat. They belong to the Wallaby class of animals in Australia which includes the Kangaroos, Koala Bears, and even Platypuses. The quokkas are considered Vulnerable in the Red List of Threatened Species of the International Union for Conservation of Nature.
It is estimated that there are 12000-14000 Quokka Australian animals left in the wild today most of which are on the Rottnest Island. The Quokkas come in groups only on this island and their population on the mainland is very scarce and scattered. The Quokkas became popular in the 2015 period due to its smile, referred to as the Quokka smile which went viral on social media platforms, especially on Instagram. Since then, a Quokka selfie has been on the to-do list of every tourist visiting Australia.
Scientific Background of Quokka
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The species name of Quokka animal is Setonix brachyurus. In the Animalia kingdom, Quokka belongs to the Chordata phylum of animals. Quokka is a mammal and females usually give birth to one offspring at a time and can give birth a maximum of two times a year. In the Chordata phylum, these animals fall into the Mammalia class. Quokka belongs to the Marsupialia infraclass within the mammals. Quokka is of Diprotodontia order within this infraclass. These animals belong to the Macropodidae family. Among the animals of the Macropodidae family, Quokka is within the Macropodinae subfamily.
The Quokka is the only member of the Setonix genus and is also called short-tailed scrub wallaby. These animals are herbivorous and the main diet includes plant stems, grass, and even some roots. These animals search for food at night and are, therefore, nocturnal animals. The Quokka is the smallest Wallaby species in the world and is closely related to Kangaroo. There are almost 50 different varieties of Wallaby species out of which Quokka is one of the three animals whose evolution is still not clear. A major difference between Quokka and other Wallaby species is that Quokka search for food when the others graze.
Genetically speaking the variation among the Quokka population is quite low, which may be due to the small area under occupation and minor differences in environment and this low variation calls for the absence of advantages or disadvantages within the population. Even with low variation levels, Quokkas often show significant heterogeneities among populations. Genetically, Quokkas have a risk of developing muscular dystrophy, which is a disease wherein the muscles of the animals weaken or get damaged.
Even though it is clear that the Quokkas belong to the Wallaby community, their exact ancestors have not been tracked down yet. Even though it has close associations with the Kangaroo, there is a primary difference in the feeding patterns, making the establishment of biological association difficult. But the one thing many scientists seem to agree with each other is that Quokkas are closely related to Rock Wallaby, a less popular species within the Wallaby family.
Physical Description and Anatomy of Quokkas
Quokkas generally weigh between 2.5kg to 5kg. they can be 40-54cm long with an additional 25-30cm tail. It has a general shape of a macropod. The Quokkas have a stocky build like almost all Wallabies. They also have well-developed hind legs and their short broadhead is accompanied by rounded ears. The original musculoskeletal system of Quokkas was generally for terrestrial bipedal saltation. But over the years they have evolved and the system now adapts for arboreal locomotion. Even with smaller hind legs and tails than the other Wallaby species, their hind legs are powerful enough to help them hop through the thick grass and shrubs.
The physical similarity of Quokka Australian animals to Kangaroos doesn’t stop them from climbing short trees and shrubs. They have grizzly brown-colored fur which is coarse and scarce to enable easy movement through the grass. The Quokkas live for almost an average of 10 years. As they are nocturnal animals, they generally sleep during the day using grass and plants as hidings. The Quokkas are also known to store fat in their long tail. They can go for a long period without eating as they store fat in their tails. Their tails also don’t have any fur on them and they also don’t use tails to balance themselves when hoping.
Fossils of Quokkas found are not old. The oldest ever fossils found are from the age of 200 years after Christopher Columbus discovered America. It was around the same time that the Europeans also found Australia. The first recorded sighting of Quokka is by a Dutch mariner Samuel Volckertzoon who mentioned Quokkas as a kind of wild cat. The sighting was also on the small islands off the west coast of Australia in 1658.
Later in 1696 another dutchman, Willem de Vlamingh who also mistook the Quokkas for large rats. This description of Quokkas as rats later became the reason to name the island Rottenest, which means Rat nest in Dutch. The name Quokka is said to be derived from the word gwaga. The word gwaga has been used to describe Quokkas in the Australian native language of Nyungar.
The Quokka population continues to thrive in the Rottenest island undisturbed even now. The establishment of an Aboriginal penal colony on the island in the 1830s kept outsiders away from the island which largely helped in protecting the animal. The Quokkas in the mainland were not that fortunate as they had to deal with a lot of threats. One of the main reasons for a decline in quokkas’ mainland population is foxes, which prey on Quokkas in the mainland. Other factors like land clearing, forest fires, and the consequent habitat loss were also reasons which pushed the Quokka population into the islands.
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Like all other Wallaby species, Quokkas are also vegetarians. Their diet mainly comprises the plant materials in their habitat. The grass is known to be their staple component in the diet, but they also eat fruits, leaves, and even stems of some other plants. A recent study found that a small shrub of the Malvaceae family, namely the Guichenotia ledifolia is Quokka's favourite shrub to snack on. Quokkas mainly browse for their food on the ground, but they also do climb trees to eat leaves and berries. They swallow their food when they find it and chew cud like coms later.
Quokkas have a high hydrating requirement and the lack of freshwater in Rottenest island is ironical to its existence there. But the Quokka population in Rottenest meets their water requirement by eating a lot of vegetation. The lack of fresh water in Rottenest island owes to the low rainfall of just 600mm in a year.
Distribution and Habitat of Quokkas
During the time of colonial settlement in Australia, the Quokkas had a widespread population over the west coast. The total area covered by Quokkas including the two islands were about 41,200-kilometre squares. The nineteenth and twentieth century saw a sharp decline in the population of Quokkas which resulted in the reduction of inhabited areas to 17,800km square. Even though they are found in large numbers on the island, the sharp downfall in mainland population has put the Quokkas on the vulnerable list.
The introduction of new predator species like the red foxes in the mainland was the prominent reason for the population decline. It is estimated that only around 4000 Quokkas are left on the mainland. The loss of habitat due to the widespread expansion of constructed structures and agricultural lands has also contributed detrimentally to the decline in the Quokka population. Logging and clearing of swamplands and grasslands have also had negative impacts on the breeding patterns of the Quokkas.
Among the 4000 Quokkas still left in the mainland, most groups have a lesser number of members. When most groups have around 50 members and the groups are generally scattered, some groups have large numbers amounting to even 700. Such large groups mostly live in the forest areas and are prone to the risk of forest fires and predators.
The population in the Rottenest island is estimated to be about 8000- 12000. The only threat to Quokkas on the island is snakes. The bald island which is far smaller than the Rottenest island has an estimated population of up to 1000. Another threat to the Quokka population living in the islands is starvation. At the end of summer and the beginning of autumn, the loss in vegetation negatively affected the Quokka population.
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The mating seasons are also different for the Quokka population living in islands and the mainland. The mainland Quokkas are known to breed all year round. But the island population breeds in the months from January to May. The Quokkas follow a promiscuous mating system. They mate during the night as they are primarily nocturnal animals.
The female Quokkas always gives birth to a single baby called a joey. They can give birth two times a year and can give birth to a total of 17 babies in their entire lifetime of about 10 years. Once born the joey lives in the mother’s pouch for about six months. After birth, the baby finds its way to the pouch on its own. After these six months, the joey wanders around closely for about two months when they are still dependant on their mother for nutrition. After about eight months after birth, the babies are independent and find food on their own.
The offsprings become sexually mature at about eighteen months of age. The female Quokka animal is dystrophyn to drop their baby and flee when attacked by a predator. When doing this the joey cries loud which attracts the predator and helps the mother to save itself. The limitations of the reproductive months in the islands when compared to the mainland are mainly due to the lack of nutrition in some months.
The Quokka is a social and friendly Wallaby that lives on the western coast and islands of Australia. They live in small family groups generally led by a dominant male. The Males protect the whole herd. The Quokkas are adored all around the world for their cuteness especially after the Quokka smile went viral on the internet a few years back. Even with their cuteness they are still vulnerable and need protection. The tourism activities themselves in Rottenest is being a source of disturbance to the Quokkas. But with the intervention of conservationists and the Australian government, we hope to see these cute little animals forever.