Fauna of Australia

The European exploration of Australia and discovery of its rich but strange animal life was late in coming. The British naval officer, Captain James Cook, sailed around Australia and charted the east coast of Australia, named it New South Wales, and claimed it for England between 1768 and 1771. In 1788, the first Europeans were transported to what is now Sydney. They were prisoners who had been sentenced by the British courts and incarcerated in prisons in Australia.

Mammals

The groups of large hopping animals that Indigenous people in northern Queensland, the Guugu Yimithirr, called gangurru (kangaroo) became a favorite source of meat to the prisoners. Like all the other native mammals, kangaroos are marsupials. Several other marsupials are also hopping animals. They range from the slightly smaller wallaby (which resembles the great gray kangaroo) to the tiny, flat-headed marsupial mouse, which weighs a mere sixth of an ounce. The koala is a well-recognized marsupial, although it is commonly called a bear because of its resemblance to a child’s teddy bear. Mainly a tree dweller, the koala's favorite food is the highly fragrant leaves of eucalyptus trees.

In addition to the diverse marsupial mammals, the fauna of Australia includes several species of placental mammals, the majority brought to the island continent by humans. Aboriginal peoples, who came to Australia about forty thousand years ago, were foragers, or hunter-gatherers. They brought no animals with them. About twenty thousand years later, or eight to ten thousand years ago, fishermen from the islands of Indonesia regularly plied the waters off the north coast of Australia in search of sea cucumbers, a large, marine, wormlike animal. These were dried on board the ship and returned to the fishermen's home islands as food. These ships likely carrried rats, which, inadvertently, were among the first placental mammals other than humans to find a foothold in Australia and quickly established themselves wherever there was food and water. These fishermen were also responsible for taking dogs with them, probably as food. Some of the dogs escaped, becoming the dingoes, or wild dogs, of Australia.

Other placental mammals were introduced by Europeans for hunting, such as the rabbit and the red fox. Both soon escaped into the wild and became serious pests, especially the rabbit. With no predators to attack them, the rabbits reproduced prodigiously, overwhelming control efforts. The fox was introduced to serve as a quarry for hunters' riding hounds, but it never reached the pest status of the rabbit. Visitors to Australia are often startled to see camels, apparently wild, striding over the sandy wastes of the Outback and other desert areas. These animals, now wild, are the descendants of domestic dromedary camels that had been used to carry freight across the deserts. A few domestic animals, principally dogs and cats, have escaped and established a feral existence. No doubt some cats were easily and swiftly caught and eaten by dingoes, crocodiles, and feral dogs. The dogs formed packs and preyed on a variety of small marsupials. They are a particular predator of the koala. Some feral dogs were preyed on by dingoes but joined dingo packs, interbred with them, and quickly became part of the predatory fauna of Australia.

The Life Cycle of Marsupials

Marsupials, as mammals, have milk-producing glands and suckle their young. They reproduce similarly to nearly all other mammals: One or more eggs, produced internally by the female, are fertilized internally by the male and develop within the female’s body. After a period of developmental stages lasting weeks or months, the fertilized egg becomes an embryo, then a fetus, and finally is ready to be born. Marsupials differ because, after only a short development period, the young fetus leaves the female’s uterus and painstakingly crawls over her abdomen to enter the brood pouch (marsupium). Here the fetus continues its development until it is a fully formed and viable organism ready to take up an external existence.

The female has prepared the way for the fetal animal to move over her abdomen by vigorously licking the surface hairs from the birth canal to the pouch. Observers had long believed the licking laid down a scent trail of saliva for the fetus to follow to the entrance of the marsupium. Recent studies suggest the licking is performed primarily to cleanse the path to be followed by the fetus.

The marsupium is endowed with nipples or teats—the number varies according to the species from one or two to a dozen or more—which the fetus takes into its mouth. This action causes the teat to swell, thus effectively sealing it into the fetus’s mouth. The quality of the mother’s milk varies during the development of the young. The milk fat increases with time to enhance the nutrition available to the developing young.

Kangaroos, Wallabies, Wombats, and Koalas

The most familiar and readily recognized Australian marsupial are the kangaroos. They range in size from the seven-foot-tall (two-meter-tall) red kangaroo, which weighs up to 200 pounds (91 kilograms), to the slightly smaller gray kangaroo, which weighs up to 165 pounds (75 kilograms) and may be as much as six feet tall. In both species, the heavy, muscular tail is nearly as long as the body. It serves as a prop when the animal is sitting and helps to balance it when it is fleeing. The kangaroo moves forward by a series of powerful hops at speeds of up to thirty miles per hour (forty-eight kilometers per hour). The small front legs are used primarily in holding objects.

Wallabies are medium-sized members of the kangaroo family. For the most part, they feed in open grasslands at night. The body size, from nose to root of the tail, is eighteen to forty-one inches (forty-six to 104 centimeters). The tail ranges from thirteen to thirty inches (thirty-three to seventy-six centimeters) long. Because of their smaller size, wallabies are preyed on to a greater extent by dingoes, feral dogs, and, in years past, the Tasmanian tiger.

Before Europeans colonized Australia and introduced sheep and beef cattle, wombats and kangaroos were the major grazers in the grasslands of the island continent. Although it is a marsupial, the wombat looks nothing like any of the other marsupials. It has been described as resembling a fur-covered barrel with four legs. An adult may weigh up to one hundred pounds (forty-five kilograms) and measure four feet in length (122 centimeters). It is a burrower, tunneling passageways one hundred feet long (thirty-one meters), six feet (almost two meters) under Earth’s surface.

The tunnels help the wombat conserve energy and water and thus reduce its need for food. Its chief foods include grasses, generally of poorer quality than required by sheep. Thus, wombats are able to survive in areas where sheep do not thrive, but if there is better quality forage available, the wombat becomes a competitor with the sheep. As a result, sheep ranchers do not like wombats. They also do not like the cylindrical, muscular animals because they burrow under fences, damaging the fence lines and opening routes for rabbits.

The rotund wombat is not a very swift animal, and many fall easy prey to dingoes and large, feral dogs. The most serious threat to the animals, however, is the automobile. Many wombats are killed on the highways as they amble across the pavement at night in search of water or new grazing.

One wombat, the northern hairy-nosed wombat, is recognized by the Australian government as critically endangered, with, as of 2024, only 315 remaining individuals living in small, protected areas in Queensland. This species is threatened by mange, agricultural expansion, and elements of climate change, such as droughts and flooding.

Along with the kangaroo, the most readily recognized Australian animal is the koala, another marsupial. The koala produces one young at a time. When it is able to spend time out of the pouch, it clings to the female’s fur and is carried along with the mother on her foraging expeditions. Much of the adult’s time is spent high in the treetops, especially eucalyptus, whose leaves are a favorite food of the animal.

The average koala male weighs from fifteen to thirty pounds (seven to fourteen kilograms) and is about two feet (sixty-one centimeters) long. The fur is thick and soft, and the animals were hunted in the fur trade. The last fur season occurred in 1927 when six thousand koalas were slaughtered. They were part of the Aboriginal peoples' diet and undoubtedly had a strong eucalyptus flavor because of their diet of eucalyptus leaves.

Although there is no longer an open season on koalas, the mortality rate is high. Loss of habitat in land clearing is a major cause of its decline. Also, the Black Summer bushfires of 2019 to 2020 devastated many forests and habitats where koalas live. In addition, many are killed by automobiles while crossing roadways. Dingoes and domestic dogs kill many of them, and a significant number drown in backyard swimming pools. Pool owners often suspend a rope in the water so that koalas that fall in can climb out. As of the early 2020s, koalas were classified as endangered by the Australian government.

The mountain pygmy possum is the only hibernating marsupial in Australia and, as of 2024, was listed as a critically endangered species due to threats from climate change, habitat destruction, and predation. It has also suffered due to a decline in its main food source, the bogong moth. These small possums, typically the size of a mouse, live exclusively in the snow-covered alpine regions of Victoria and New South Wales.

Tasmanian Tigers and Devils

Most of the marsupials in Australia have maintained a somewhat shaky coexistence with the European settlers. Two, however, have not. The Tasmanian tiger (more commonly called the thylacine) was the largest living carnivorous marsupial known. It resembled a large, long dog with a long, stiff tail and brown fur marked with thirteen to twenty dark brown to black stripes on the rear portion of the body. It was active mostly at night and preyed on small animals and birds. The thylacine also occasionally killed and ate sheep and chickens kept by European settlers. It was a fearsome-looking animal, but it was shy and secretive, avoiding contact with humans.

Thylacine females had a back-opening pouch with three to four young in a litter. Pouch life is presumed to have been about four months. The Europeans feared the thylacine, probably because of its bizarre appearance, its nocturnal habits, and its presumed attacks on domestic animals. A bounty was placed on the animal, and it was trapped, poisoned, and shot. The last known thylacine died in an Australian zoo in September 1936. Occasional sightings of thylacines have been reported, but in 1986, the species was declared extinct.

The Tasmanian devil, although it is a relative of the thylacine, differs in several ways. Devils are smaller, about two feet long with a tail about one foot long. They weigh up to twenty-six pounds (twelve kilograms) and are heavily built, with a broad head and a short, thick tail. The devil’s powerful jaws and strong teeth help it to completely devour its food, bones, fur, and all. It is mainly a scavenger and will eat whatever is available. Wallabies, small mammals, and birds are included in its diet, either captured alive or scavenged as a carcass. It has been suggested that the Tasmanian devil helps maintain countryside sanitation by cleaning up carcasses.

The female devil has a back-opening pouch with four nipples. Since more than four young are born in a litter, the extra young die. On average, about two or three young survive in the pouch.

It is the coloration and behavior of the devil that have given it a fearsome reputation. The fur is black, sometimes marked with white patches, and it makes eerie screeches as it ambles about at night in search of food. At one time, the Tasmanian devil was widely distributed on mainland Australia, but in modern times it is restricted to the island of Tasmania, off the southeast coast of the mainland. It is believed that the dingo ousted the devil from the mainland. The Tasmanian devil’s population declined by more than 85 percent between 1990 and 2020. In 2008, the Tasmanian devil was listed on the endangered species list, and in the early 2020s, it remained there.

Reptiles

Australian reptiles consist of many species of snakes—some poisonous—several monitor lizards (related to the Komodo dragon), and the most feared reptile, the crocodile. The largest monitor lizard, the giant goanna, reaches a length of almost nine feet (274 centimeters). It lives in rock crevices in desert regions, feeding on any animals that come within reach.

The estuarine or saltwater crocodile is the largest and probably most dangerous Australian reptile. Specimens thirty feet long have been captured, and there may be a few larger than that in some isolated coastal marshes. It can live in freshwater billabongs, brackish coastal estuaries, and has been observed swimming 150 miles (241 kilometers) out at sea. Its diet consists of any animals that come to waterways to bathe or drink, and it will attack and eat humans. Indeed, many Australian rivers, especially those in the Northern Territory, are marked with signs that warn visitors to beware of crocodiles in the water. The animals once were actively hunted for their hides, to be made into expensive shoes and bags. Pre-hunting populations were estimated at more than 150,000 crocodiles from Western Australia to Queensland. Hunting pressure reduced their numbers to about seven thousand individuals, but it rebounded to more than seventy thousand after hunting was banned. The crocodile population was closely monitored, and a limited number could be taken for their hides and meat through the end of the twentieth and beginning of the twenty-first century. By the early 2000s, the saltwater crocodile had regained its population.

Birds

The best known of Australian birds are the parrots. Many species of parrots are collected for the pet trade, the most popular being the small budgerigar or parakeet. They are aptly called “love birds” because of the apparent kissing that goes on between pairs of the “budgies.” Some of them can be taught to mimic human speech. Some Australian birds are not as well-known as the diminutive (6.5 inch or 16.5 centimeter) budgerigar. Bowerbirds build elaborate structures of branches, grasses, and bits of bone or shell to attract females for mating. The kookaburra, though not often seen, is aptly named the “laughing jackass bird” because of its loud and very distinctive call.

Australia’s birds also include two large, flightless species—the cassowary and the emu. Cassowaries are about fifty-two to sixty-five inches tall (132 to 165 centimeters) and weigh up to 140 pounds (64 kilograms). The skin of the head and neck, in both males and females, is bare of feathers, with bright red, yellow, blue, and purple skin. The top of the head bears a bony structure called a casque. Cassowaries inhabit the tropical rainforests of the Australian northeast coastal region. They are well-muscled and dangerous; they can kill a human by leaping feet first and raking the intruder with sharp claws.

Like the cassowary, the emu is a large, flightless bird. At five to six feet in height (152 to 183 centimeters), it is topped only by the African ostrich. Emus are found throughout Australia, feeding on fruits, seeds, roots, and occasionally insects. They are pests for farms because of their liking for cereal grains. They are eaten by Aboriginal peoples and Europeans in the Outback. Attempts to farm them for the American market as a novelty food have not proved to be very successful.

Placental Mammals

Prior to the arrival of humans, especially Europeans, the Australian mammalian fauna consisted almost entirely of marsupials. One major exception was the flying fox, also known as the large fruit bat. Undoubtedly the earliest bats flew or were blown by storm winds, from the Asian mainland. With few natural enemies, the bats thrived in the tropical and subtropical forests. They continue to be abundant today. Almost all other placental mammals, such as the dingo, were introduced to Australia with the arrival of humans.

Fossil remains indicate the dingo has been a feature of the outback for about four thousand years. Contrary to earlier beliefs, it probably did not arrive with the Aboriginal peoples forty thousand years ago but is a relative newcomer. Research by Dr. Laurie Corbett, a scientist with the Australian Commonwealth Scientific and Industrial Research Organization (CSIRO) in Darwin, suggests the dingo ancestors were transported, perhaps as food, aboard Malaysian fishing boats. Once in the wild, they soon found a good supply of game in the populations of ground-dwelling marsupials. When Europeans began to raise sheep and beef cattle, the dingo quickly found them a ready source of food. Research on dingo behavior revealed the animals often simply scatter the flocks or, at worse, ravage the animals without eating the carcasses.

To control the dingo, the Australian government erected a wire mesh fence six feet high (183 centimeters), extending nearly four thousand miles (or over six thousand kilometers) across the country. Many ranchers attempted to control the dingo by any means, including poison, traps, and guns. Dr. Corbett reported that the animal, as a separate species, may have been naturally sliding toward extinction by being absorbed into the domestic dog population through interbreeding. By the early 2020s, they were listed as threatened and vulnerable to extinction because of the continued trapping and killing of the animal.

The interior sections of Australia, well away from the moist climate of the coastal regions, resemble what most people think of as desert. Vast wastelands of sand and gravel are interspersed with billabongs and other water courses. To complete the desert picture, groups of wild camels troop across as they seek favorable grazing and water. The camels are not native but were introduced in the nineteenth century to serve as beasts of burden. The trails they followed served as lifelines for most of inland Australia. The animals brought food and other supplies to the settlements, mines, and sheep stations.

The settlers chose the one-humped dromedary, or Arabian camel, rather than the two-humped Bactrian camel. The Bactrian is an animal of the cold Eurasian steppes, whereas the dromedary is common in the hot deserts of Africa and thus better able to survive in the conditions of Australia. Their cloven hooves have cushioned pads underneath that spread with each step and provide good traction in the loose sand and gravel. The hump stores energy-rich fat, and the animals conserve water by minimizing perspiration and recycling moisture exhaled through the nostrils.

At their peak, there were between ten thousand and twenty thousand dromedaries on the desert trails of Australia. However, when road improvements and motor trucks came along, the camels were no longer needed. The camel owners slaughtered some for food and their hides, the rest were driven into the Outback and set free. Here, they thrived and multiplied. Early twenty-first century estimates of their numbers placed the population of feral camels as high as one million animals. However, this number was later considered an over-estimation. Though researchers and wildlife officials differ on their estimated counts, in 2021, the government of South Australia estimated that, because of culling and other methods of population control, the number of feral camels throughout Australia was around 300,000.

The now-wild camels are a nuisance to sheep and cattle station owners. The camels knock down fences, release the livestock, and provide entry ways for predatory dingoes. They also eat extreme amounts of vegetation throughout the country. However, the resourceful Australians are turning a nuisance to a profit. Many of the feral camels are being harvested for food, wool, and leather. In visitor centers, such as Alice Springs, Uluru (Ayer’s Rock) National Park, and Ratatjuta, camels are available for rides, either as “picture opportunities” or for guided tours through the Outback.

While the camel and dingo may be considered nuisances, the European rabbit turned out to be an obnoxious pest. In 1859, a homesick Australian stock grazer imported two dozen European rabbits from England and released them on his land. The rabbits bred prodigiously, and six years later, he killed twenty thousand on the ranch. In 1895, twenty million rabbits were killed, and still, they increased. Five rabbits eat as much grass as one sheep. The rabbits spread over the countryside like a plague. Rabbit-proof fences were erected, but usually, the rabbits had already gotten through. By 1953, over a billion rabbits were inhabiting 1.2 million square miles (389 square kilometers) of Australian grassland.

After years of fruitless efforts to control the rabbits, scientists introduced a disease organism, myxoma, a virus, and within one year, 95 percent of the rabbits were dead. However, in the long run, the control agent was not completely successful. A few rabbits were naturally immune to the disease, and others developed immunity and continued to reproduce. Unfortunately, the virus evolved to an avirulent form. Thus, the biological control of the rabbit is no longer as effective as it once was.

Principal Terms

Aboriginal peoples/First Nation Australians: European name for the Native Australians

Marsupial: A type of mammal where the females possess an external abdominal pouch in which the young are suckled and protected

Monotreme: A primitive mammal that lays eggs, such as the duck-bill platypus

Placental: A mammal in which the developing young are nurtured via a blood-rich tissue (the placenta) within the mother’s body

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