Emu

The Emu () (Dromaius novaehollandiae) is the largest bird native to Australia and the only extant member of the genus Dromaius. It is also the second-largest extant bird in the world by height, after its ratite relative, the ostrich. There are three extant subspecies of Emus in Australia. The Emu is common over most of mainland Australia, although it avoids heavily populated areas, dense forest, and arid areas. They are opportunistically nomadic and may travel long distances to find food; they feed on a variety of plants and insects, but have been known to go weeks without food. They also ingest stones, glass shards and bits of metal that help squash food in the digestive system. They drink infrequently, often once every day or two, and ingest copious fluids when the opportunity arises. Emus will sit in water and are also able to swim. They are curious and nosy animals who are known to follow and watch other animals and humans. Emus do not sleep continuously at night but in several short stints sitting down.

Emus have a nail on their toes, akin to a knife, which is used in kicking away predators and opponent Emus. Their legs are among the strongest of any animals, allowing them to rip metal wire fences. They are endowed with good eyesight and hearing, which allows them to detect predators in the vicinity. The plumage on an eye varies regionally, matching the surrounding environment and improving its camouflage. The feathers allow the Emu to prevent heat from flowing into the skin, permitting it to be active during the midday heat. They can tolerate a wide range of temperatures and thermoregulate effectively. Males and females are hard to distinguish visually, but can be differentiated by the types of loud sounds they emit by manipulating an inflatable neck sac. Emus breed in May and June and are not monogamous; fighting among females for a mate is common. Females can mate several times and lay several batches of eggs in one season. The animals put on weight before the breeding season, and the male does most of the incubation, losing significant weight during this time as he does not eat. The eggs hatch after around eight weeks, and the young are nurtured by their fathers. They reach full size after around six months, but can remain with their family until the next breeding season half a year later. Emus can live between 10 and 20 years in the wild and are predated by dingos, eagles and hawks. They can jump and kick to avoid dingos, but against eagles and hawks, they can only try to run and swerve.

The Tasmanian Emu subspecies that previously inhabited Tasmania became extinct after the European settlement of Australia in 1788; and the distribution of the mainland subspecies has been influenced by human activities. Once common on the east coast, Emu are now uncommon; by contrast, the development of agriculture and the provision of water for stock in the interior of the continent have increased the range of the Emu in arid regions, and it is neither endangered or vulnerable. They were a food and fuel source for indigenous Australians and early European settlers. Emus are farmed for their meat, oil, and leather. Emu is a lean meat and while it is often claimed by marketers that the oil has anti-inflammatory and anti-oxidative effects, this has not been scientifically verified in humans. The Emu is an important cultural icon of Australia. It appears on the coat of arms, various coins, features prominently in Indigenous Australian mythology, and hundreds of places are named after the bird.

Taxonomy and distribution

There are reports the Emu was first sighted by European explorers in 1696 when they made a brief visit to the coast of Western Australia. It was thought to have been spotted on the east coast of Australia before 1788 when the first European settlement occurred. It was first described under the name of the New Holland Cassowary in Arthur Phillip's Voyage to Botany Bay, published in 1789. The species was named by ornithologist John Latham on a specimen from the Sydney, Australia area, which was referred to as New Holland at the time. The etymology of the common name Emu is uncertain, but is thought to have come from an Arabic word for large bird that was later used by Portuguese explorers to describe the related Cassowary in Australia and New Guinea. It was known as murawung or birabayin to the local Eora and Darug inhabitants of the Sydney basin.

In his original 1816 description of the Emu, Vieillot used two generic names; first Dromiceius, then Dromaius a few pages later. It has been a point of contention ever since which is correct; the latter is more correctly formed, but the convention in taxonomy is that the first name given stands, unless it is clearly a typographical error. Most modern publications, including those of the Australian government, use Dromaius, with Dromiceius mentioned as an alternative spelling. D. novaehollandiae diemenensis, a subspecies known as the Tasmanian Emu, became extinct around 1865. Emus were introduced to Maria Island off Tasmania and Kangaroo Island near South Australia during the 20th century. The Kangaroo Island birds have established a breeding population there. The Maria Island population became extinct in the mid-1990s.

There are three extant subspecies in Australia:

In the southeast, D. novaehollandiae novaehollandiae, with its whitish ruff when breeding;

In the north, D. novaehollandiae woodwardi, slender and paler; and

In the southwest, D. novaehollandiae rothschildi, darker, with no ruff during breeding.

Description

Emus are large birds. The largest can reach up to in height, at the shoulder. Emus weigh between . Females are usually larger than males by a small amount, but substantially wider across the rump. Their ability to run at high speeds, 48 km/h (30 mph), When walking, the Emu takes steps of around , but at full gallop, a stride can be as long as . The toe and claw are a total of . They have a soft bill, adapted for grazing. allowing the bird to be active during the heat of the day. A unique feature of the Emu feather is its double rachis emerging from a single shaft. Both of the rachis have the same length, and the texture is variable; the near the quill it is rather furry, but the external ends resemble grass. although the male's penis can become visible when it defecates. The plumage varies in colour due to environmental factors, giving the bird a natural camouflage. Feathers of Emus in more arid area with red soil have a similarly tinted plumage but are darker in animals residing in damp conditions. For normal breathing in cooler weather, they have large, multifolded nasal passages. Cool air warms as it passes through into the lungs, extracting heat from the nasal region. On exhalation, the Emu's cold nasal turbinates condense moisture back out of the air and absorb it for reuse. As with other ratites, the Emu has great homeothermic ability, and can maintain this status from -5 to 45 degrees. The thermoneutral zone of Emus lies between 10–15 degrees and 30 degrees.

As with other ratites, the Emu has a relatively low rate of metabolism compared to other types of birds, but the rate depends on activity, especially due to resulting changes to thermodynamics. At -5 degrees, the metabolism rate of an Emu while sitting down is around 60% of the value for one that is standing, as the lack of feathers under its stomach leads to a higher rate of heat loss when it is standing up and exposing the underbelly.

Emus sleep during the night, and begin to settle down at sunset, although it does not sleep continuously throughout the night. It can awake and arise up to eight times per night in order to feed or defecate. Before going into a deep sleep, the emu squats on its tarsus and begins to enter a drowsy state. However, it is alert enough to react to visual or aural stimuli and return to an awakend state. During this time, the neck descends closer to the body and the eyelids begin to lower. An Emu will typically awake from the deep sleep one every 90–120 minutes and stand in a tarsal position to eat or defecate. This lasts for 10–20 minutes and the cycle is repeated 4–6 times during most nights. This forms a large part of its protein requirements and intake. They are also known to eat wheat crops, and any fruit or other crops that it can access, easily climbing over high fences if required. One undesirable effect of this occurred in Queensland in the 1930s and 1940s when Emus ate cactus in the outback there. They defecated the seeds in various places as they moved around, spreading the unwanted plant. This led of constant hunting campaigns to stop the cactus from being spread.

Emus also require pebbles and stones to assist in the digestion of the plant material. Individual stones may weigh and they may have as much as in their gizzard at one time. They also eat charcoal, however scientists still have not ascertained why. They are observed to prefer kneeling on solid earth while drinking, rather than in rocks or mud, presumably due to a fear of sinking.

It is the females that court the males, and during the mating season, they become physically more attractive. The female's plumage darkens slightly and the small patches of bare, hairless skin just below the eyes and near the beaks turn turqoise-blue, although this is a subtle change. This calling can occur when the males are not in view and more than away and when the male's attention has been gained, the female can circle in a radius of 10–40 m. If a female tried to woo a male that already had a partner, the incumbent female will try and repel the competitor by walking towards her challenger and staring in a stern way. If the male showed interest in the second female by erecting his feathers and swaying from side to side, the incumbent female will attack the challenger, usually resulting in a backdown by the new female.

If a male is interested, he will stretch his neck and erect his feathers and bend over and peck at the ground. He will then sidle up to the female, swaying his body and neck from side to side, and rubbing his breast against his partner's rump, usually without calling out. The female would accept by sitting down and raising her rump. which is roughly equivalent to 10–12 chicken eggs in volume and weight. The first verified occurrence of genetically identical avian twins was demonstrated in the Emu. The egg surface is granulated and pale green. During the incubation period, the egg turns dark green, although if the egg never hatches, it will turn white from the bleaching effect of the sun.

The male becomes broody after his mate starts laying, and begins to incubate the eggs before the laying period is complete. From this time on, he does not eat, drink, or defecate, and stands only to turn the eggs, which he does about 10 times a day. Sometimes he will walk away at night; he chooses such a time as most predators of emu eggs are not nocturnal. Some females stay and defend the nest until the chicks start hatching, but most leave the nesting area completely to nest again; in a good season, a female Emu may nest three times. If the parents stay together during the incubation period, they will take turns standing guard over the eggs while the other drinks and feeds within earshot.

Incubation takes 56 days, and the male stops incubating the eggs shortly before they hatch. Newly hatched chicks are active and can leave the nest within a few days. They stand about tall, weigh , As the young Emus cannot travel far, the parents must choose an area with plentiful food in which to breed. captive birds can live longer than those in the wild.

Emus are predated by a few animals, including dingos, eagles and hawks. Foxes try and steal incubating eggs, while the other three also attack adults. Birds of prey and the dingo try to kill the Emu by attacking the head. The Emu tries to repel the dingo by jumping into the air and kicking or stamping the dingo on its way down. The Emu jumps as the dingo barely has a the capacity to jump high enough to threaten its neck, so a correctly timed leap to coincide with the dingo's lunge can keep its head and neck out of danger. Wedge-tailed eagles and hawks attack Emus by swooping downwards rapidly and at high speed and aiming for the head and neck. In this case, the Emu's jumping technique as employed against the dingo is not useful. The birds try to target the Emu in open ground so that it cannot hide behind obstacles. Under such circumstances, the Emu can only run in a chaotic manner and change directions frequently to try and evade its predator. They also sometimes disguised themselves using the skins of Emus they had previously killed.

The early white settlers also used Emu fat for fuelling lamps. Their occurrence range is between , and a 1992 population estimate was between 630,000 and 725,000. Although the population of Emus on mainland Australia is thought to be higher now than before European settlement,

Economic value

, US]] The Emu was an important source of meat to the Aborigines in the areas to which it was endemic. Emu fat was used as bush medicine, and was rubbed on the skin. It also served as a valuable lubricant. It was mixed with ochre to make the traditional paint for ceremonial body adornment, as well as to oil wooden tools and utensils such as the coolamon.

An example of how the Emu was cooked comes from the Arrernte of Central Australia who call it Kere ankerre:

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Commercial Emu farming started in Western Australia in 1987 and the first slaughtering occurred in 1990. In Australia, the commercial industry is based on stock bred in captivity and all states except Tasmania have licensing requirements to protect wild Emus. Outside Australia, Emus are farmed on a large scale in North America, with about 1 million birds in the US, Peru, and China, and to a lesser extent in some other countries. Emus breed well in captivity, and are kept in large open pens to avoid leg and digestive problems that arise with inactivity. They are typically fed on grain supplemented by grazing, and are slaughtered at 50–70 weeks of age. They eat two times a day and prefer of leaves each meal.

Emus are farmed primarily for their meat, leather, and oil. Emu meat is a low-fat meat (less than 1.5% fat), and with cholesterol at 85 mg/100 g, it is comparable to other lean meats. Most of the usable portions (the best cuts come from the thigh and the larger muscles of the drum or lower leg) are, like other poultry, dark meat; Emu meat is considered for cooking purposes by the USDA to be a red meat because its red colour and pH value approximate that of beef, but for inspection purposes it is considered poultry. Emu fat is rendered to produce oil for cosmetics, dietary supplements, and therapeutic products. The oil is harvested from the subcutaneous and retroperitoneal fat from the macerated adipose tissue, and filtering the liquefied fat to get the oil, and has been used by indigenous Australians and the early white settlers for purported healing benefits. It has been scientifically shown to improve the rate of wound healing, but the mechanism responsible for such aforementioned effects is not understood. While there are no scientific studies showing that emu oil is effective in humans, it is marketed and promoted as a dietary supplement with a wide variety of claimed health benefits. Commercially marketed emu oil supplements are poorly standardised. Such products are sometimes marketed deceptively; the USFDA highlighted emu oil in a 2009 article on "How to Spot Health Fraud".

Emu leather has a distinctive patterned surface, due to a raised area around the feather follicles in the skin; the leather is used in such small items as wallets and shoes, often in combination with other leathers. The feathers and eggs are used in decorative arts and crafts.

Cultural references

The Emu has a prominent place in Australian Aboriginal mythology, including a creation myth of the Yuwaalaraay and other groups in NSW who say that the sun was made by throwing an Emu's egg into the sky; the bird features in numerous aetiological stories told across a number of Aboriginal groups. One story from Western Australia holds that a man once annoyed a small bird, who responded by throwing a boomerang, severing the arms of the man and transforming him into a flightless Emu. The Kurdaitcha man of Central Australia is said to wear sandals made of Emu feathers to mask his footprints. Many Aboriginal language groups throughout Australia have a tradition that the dark dust lanes in the Milky Way represent a giant emu. Several of the Sydney rock engravings depict an Emu. The animals are also depicted in indigenous dances.

The Emu is popularly but unofficially considered as a faunal emblem—the national bird of Australia. It appears as a shield bearer on the Coat of arms of Australia with the Red Kangaroo and as a part of the Arms also appears on the Australian 50 cent coin. It has featured on numerous Australian postage stamps, including a pre-federation New South Wales 100th Anniversary issue from 1888, which featured a 2 pence blue Emu stamp, a 36 cent stamp released in 1986, and a $1.35 stamp released in 1994. The hats of the Australian Light Horse are famously decorated with an Emu feather plume.

There are around 600 gazetted places named after the Emu in Australia, including mountains, lakes, creeks, and towns. During the 19th and 20th centuries, many Australian companies and household products were named after the bird; for example, in Western Australia, Emu branded beer has been produced since the early 20th century. The Swan Brewery continues to produce a range of Emu branded beers. Emu – Austral Ornithology is the quarterly peer-reviewed publication of the Royal Australasian Ornithologists Union, also known as Birds Australia.

The late comedian, Rod Hull, featured an emu puppet in his act.

See also

Ostrich

Greater Rhea

Birds of Australia

Fauna of Australia

==Notes==

References

External links

Emu chicks emerging, article with sound clips, photos and videos.

"Kangaroo feathers" and the Australian Light Horse from the Australian War Memorial

Emu videos, photos & sounds on the Internet Bird Collection

A discussion of Emu eggs and how to cook them

Category:Birds of South Australia Category:Birds of Tasmania Category:Birds of Western Australia Category:Bushfood Category:Casuariidae Category:Dromaius Category:Flightless birds Category:Domesticated birds Category:Heraldic birds Category:Megafauna of Australia Category:National symbols of Australia Category:Ratites Category:Monotypic bird genera Category:Animals described in 1790