Emu

Emus were first reported as having been seen by Europeans when explorers visited the western coast of Australia in 1696. This was during an expedition led by Dutch captain Willem de Vlamingh who was searching for survivors of a ship that had gone missing two years earlier.[11] The birds were known on the eastern coast before 1788, when the first Europeans settled there.[7] The birds were first mentioned under the name of the "New Holland cassowary" in Arthur Phillip's Voyage to Botany Bay, published in 1789 with the following description:[12][13]

This is a species differing in many particulars from that generally known, and is a much larger bird, standing higher on its legs and having the neck longer than in the common one. Total length seven feet two inches. The bill is not greatly different from that of the common Cassowary; but the horny appendage, or helmet on top of the head, in this species is totally wanting: the whole of the head and neck is also covered with feathers, except the throat and fore part of the neck about half way, which are not so well feathered as the rest; whereas in the common Cassowary the head and neck are bare and carunculated as in the turkey. The plumage in general consists of a mixture of brown and grey, and the feathers are somewhat curled or bent at the ends in the natural state: the wings are so very short as to be totally useless for flight, and indeed, are scarcely to be distinguished from the rest of the plumage, were it not for their standing out a little. The long spines which are seen in the wings of the common sort, are in this not observable,—nor is there any appearance of a tail. The legs are stout, formed much as in the Galeated Cassowary, with the addition of their being jagged or sawed the whole of their length at the back part.

Mounted emu skeleton

The species was named by ornithologist John Latham in 1790 based on a specimen from the Sydney area of Australia, a country which was known as New Holland at the time.[3][14] He collaborated on Phillip's book and provided the first descriptions of, and names for, many Australian bird species; Dromaius comes from a Greek word meaning "racer" and novaehollandiae is the Latin term for New Holland, so the name can be rendered as "fast-footed New Hollander".[15] In his original 1816 description of the emu, the French ornithologist Louis Jean Pierre Vieillot used two generic names, first Dromiceius and later Dromaius.[16] It has been a point of contention ever since as to which name should be used; the latter is more correctly formed, but the convention in taxonomy is that the first name given to an organism stands, unless it is clearly a typographical error.[17] Most modern publications, including those of the Australian government,[5] use Dromaius, with Dromiceius mentioned as an alternative spelling.[5]

The emu was long classified, with its closest relatives the cassowaries, in the family Casuariidae, part of the ratite order Struthioniformes.[18] An alternate classification was proposed in 2014 by Mitchell et al., based on analysis of mitochondrial DNA. This splits off the Casuariidae into their own order, the Casuariformes,[19] and includes only the cassowaries in the family Casuariidae, placing the emus in their own family, Dromaiidae. The cladogram shown below is from their study.[20]

Two different Dromaius species were present in Australia at the time of European settlement, and one additional species is known from fossil remains. The insular dwarf emus, D. n. baudinianus and D. n. minor, originally present on Kangaroo Island and King Island respectively, both became extinct shortly after the arrival of Europeans.[6][21] D. n. diemenensis, another insular dwarf emu from Tasmania, became extinct around 1865. The mainland subspecies, D. n. novaehollandiae, remains common. The population of these birds varies from decade to decade, largely being dependent on rainfall; in 2009, it was estimated that there were between 630,000 and 725,000 birds.[22] Emus were introduced to Maria Island[23] off Tasmania, and Kangaroo Island off the coast of South Australia, during the 20th century. The Maria Island population died out in the mid-1990s. The Kangaroo Island birds have successfully established a breeding population.[24]

In 1912, the Australian ornithologist Gregory M. Mathews recognised three living subspecies of emu,[25] D. n. novaehollandiae (Latham, 1790),[26] D. n. woodwardi Mathews, 1912[27] and D. n. rothschildi Mathews, 1912.[28] The Handbook of the Birds of the World, however, argues that the last two of these subspecies are invalid; natural variations in plumage colour and the nomadic nature of the species make it likely that there is a single race in mainland Australia.[29][30] Examination of the DNA of the King Island emu shows this bird to be closely related to the mainland emu and hence best treated as a subspecies.[21]

Emus forage in a diurnal pattern and eat a variety of native and introduced plant species. The diet depends on seasonal availability with such plants as Acacia, Casuarina and grasses being favoured.[29] They also eat insects and other arthropods, including grasshoppers and crickets, beetles, cockroaches, ladybirds, bogong and cotton-boll moth larvae, ants, spiders and millipedes.[29][48] This provides a large part of their protein requirements.[49] In Western Australia, food preferences have been observed in travelling emus; they eat seeds from Acacia aneura until the rains arrive, after which they move on to fresh grass shoots and caterpillars; in winter they feed on the leaves and pods of Cassia and in spring, they consume grasshoppers and the fruit of Santalum acuminatum, a sort of quandong.[32][50] They are also known to feed on wheat,[51] and any fruit or other crops that they can access, easily climbing over high fences if necessary.[49] Emus serve as an important agent for the dispersal of large viable seeds, which contributes to floral biodiversity.[50][52] One undesirable effect of this occurred in Queensland in the early twentieth century when emus fed on the fruit of prickly pears in the outback. They defecated the seeds in various places as they moved around, and this led to a series of campaigns to hunt emus and prevent the seeds of the invasive cactus being spread.[49] The cacti were eventually controlled by an introduced moth (Cactoblastis cactorum) whose larvae fed on the plant, one of the earliest examples of biological control.[53]

Small stones are swallowed to assist in the grinding up and digestion of the plant material. Individual stones may weigh 45 g (1.6 oz) and the birds may have as much as 745 g (1.642 lb) in their gizzards at one time. They also eat charcoal, although the reason for this is unclear.[32] Captive emus have been known to eat shards of glass, marbles, car keys, jewellery and nuts and bolts.[49]

Emus drink infrequently but ingest large amounts when the opportunity arises. They typically drink once a day, first inspecting the water body and surrounding area in groups before kneeling down at the edge to drink. They prefer being on firm ground while drinking, rather than on rocks or mud, but if they sense danger, they often stand rather than kneel. If not disturbed, they may drink continuously for ten minutes. Due to the scarcity of water sources, emus are sometimes forced to go without water for several days. In the wild, they often share water holes with kangaroos, other birds and animals; they are wary and tend to wait for the other animals to leave before drinking.[54]

Dark green emu egg

Emus form breeding pairs during the summer months of December and January and may remain together for about five months. During this time, they stay in an area a few kilometres in diameter and it is believed they find and defend territory within this area. Both males and females put on weight during the breeding season, with the female becoming slightly heavier at between 45 and 58 kg (99 and 128 lb). Mating usually takes place between April and June; the exact timing is determined by the climate as the birds nest during the coolest part of the year.[40] During the breeding season, males experience hormonal changes, including an increase in luteinising hormone and testosterone levels, and their testicles double in size.[55]

Males construct a rough nest in a semi-sheltered hollow on the ground, using bark, grass, sticks and leaves to line it.[3] The nest is almost always a flat surface rather than a segment of a sphere, although in cold conditions the nest is taller, up to 7 cm (2.8 in) tall, and more spherical to provide some extra heat retention. When other material is lacking, the bird sometimes uses a spinifex tussock a metre or so across, despite the prickly nature of the foliage.[40] The nest can be placed on open ground or near a shrub or rock. The nest is usually placed in an area where the emu has a clear view of its surroundings and can detect approaching predators.[56]

Female emus court the males; the female's plumage darkens slightly and the small patches of bare, featherless skin just below the eyes and near the beak turn turquoise-blue. The colour of the male's plumage remains unchanged, although the bare patches of skin also turn light blue. When courting, females stride around, pulling their neck back while puffing out their feathers and emitting low, monosyllabic calls that have been compared to drum beats. This calling can occur when males are out of sight or more than 50 metres (160 ft) away. Once the male's attention has been gained, the female circles her prospective mate at a distance of 10 to 40 metres (30 to 130 ft). As she does this, she looks at him by turning her neck, while at the same time keeping her rump facing towards him. If the male shows interest in the parading female, he will move closer; the female continues the courtship by shuffling further away but continuing to circle him.[40][41]

If a male is interested, he will stretch his neck and erect his feathers, then bend over and peck at the ground. He will circle around and sidle up to the female, swaying his body and neck from side to side, and rubbing his breast against his partner's rump. Often the female will reject his advances with aggression, but if amenable, she signals acceptance by squatting down and raising her rump.[41][57]

Nest and eggs

Females are more aggressive than males during the courtship period, often fighting for access to mates, with fights among females accounting for more than half the aggressive interactions during this period. If females court a male that already has a partner, the incumbent female will try to repel the competitor, usually by chasing and kicking. These interactions can be prolonged, lasting up to five hours, especially when the male being fought over is single and neither female has the advantage of incumbency. In these cases, the females typically intensify their calls and displays.[41]

The sperm from a mating is stored by the female and can suffice to fertilise about six eggs.[57] The pair mate every day or two, and every second or third day the female lays one of a clutch of five to fifteen very large, thick-shelled, green eggs. The shell is around 1 mm (0.04 in) thick, but rather thinner in northern regions according to indigenous Australians.[3][56] The eggs are on average 13 cm × 9 cm (5.1 in × 3.5 in) and weigh between 450 and 650 g (1.0 and 1.4 lb).[58] The maternal investment in the egg is considerable, and the proportion of yolk to albumen, at about 50%, is greater than would be predicted for a precocial egg of this size. This probably relates to the long incubation period which means the developing chick must consume greater resources before hatching.[59] The first verified occurrence of genetically identical avian twins was demonstrated in the emu.[60] 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.[61]

The male becomes broody after his mate starts laying, and may begin to incubate the eggs before the clutch is complete. From this time on, he does not eat, drink, or defecate, and stands only to turn the eggs, which he does about ten times a day.[61] He develops a brood patch, a bare area of wrinkled skin which is in intimate contact with the eggs.[62] Over the course of the eight-week incubation period, he will lose a third of his weight and will survive on stored body fat and on any morning dew that he can reach from the nest. As with many other Australian birds, such as the superb fairywren, infidelity is the norm for emus, despite the initial pair bond: once the male starts brooding, the female usually wanders off, and may mate with other males and lay in multiple nests; thus, as many as half the chicks in a brood may not be fathered by the incubating male, or even by either parent, as emus also exhibit brood parasitism.[63]

Emu chicks have longitudinal stripes that provide camouflage

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.[42] 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.[64] If it perceives a threat during this period, it will lie down on top of the nest and try to blend in with the similar-looking surrounds, and suddenly stand up to confront and scare the other party if it comes close.[64]

Incubation takes 56 days, and the male stops incubating the eggs shortly before they hatch.[42] The temperature of the nest rises slightly during the eight-week period. Although the eggs are laid sequentially, they tend to hatch within two days of one another, as the eggs that were laid later experienced higher temperatures and developed more rapidly.[47] During the process, the precocial emu chicks need to develop a capacity for thermoregulation. During incubation, the embryos are kept at a constant temperature but the chicks will need to be able to cope with varying external temperatures by the time they hatch.[47]

Newly hatched chicks are active and can leave the nest within a few days of hatching. They stand about 12 cm (5 in) tall at first, weigh 0.5 kg (17.6 oz),[32] and have distinctive brown and cream stripes for camouflage, which fade after three months or so. The male guards the growing chicks for up to seven months, teaching them how to find food.[32][65] Chicks grow very quickly and are fully grown in five to six months;[32] they may remain with their family group for another six months or so before they split up to breed in their second season. During their early life, the young emus are defended by their father, who adopts a belligerent stance towards other emus, including the mother. He does this by ruffling his feathers, emitting sharp grunts, and kicking his legs to drive off other animals. He can also bend his knees to crouch over smaller chicks to protect them. At night, he envelops his young with his feathers.[66] As the young emus cannot travel far, the parents must choose an area with plentiful food in which to breed.[51] In captivity, emus can live for upwards of ten years.[29]

Emu and chicks, from The Birds of Australia, John Gould, 1848

There are few native natural predators of emus still extant. Early in its species history it may have faced numerous terrestrial predators now extinct, including the giant lizard Megalania, the thylacine, and possibly other carnivorous marsupials, which may explain their seemingly well-developed ability to defend themselves from terrestrial predators. The main predator of emus today is the dingo, which was originally introduced by Aboriginals thousands of years ago from a stock of semi-domesticated wolves. Dingoes try to kill the emu by attacking the head. The emu typically 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 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.[67]

Despite the potential prey-predator relationship, the presence of predaceous dingoes does not appear to heavily influence emu numbers, with other natural conditions just as likely to cause mortality.[68] Wedge-tailed eagles are the only avian predator capable of attacking fully-grown emus, though are perhaps most likely to take small or young specimens. The eagles 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 to evade its attacker.[67][69] Other raptors, monitor lizards, introduced red foxes, feral and domestic dogs, and feral pigs occasionally feed on emu eggs or kill small chicks.[2]

Emus can suffer from both external and internal parasites, but under farmed conditions are more parasite-free than ostriches or rheas. External parasites include the louse Dahlemhornia asymmetrica and various other lice, ticks, mites and flies. Chicks sometimes suffer from intestinal tract infections caused by coccidian protozoa, and the nematode Trichostrongylus tenuis infects the emu as well as a wide range of other birds, causing haemorrhagic diarrhoea. Other nematodes are found in the trachea and bronchi; Syngamus trachea causing haemorrhagic tracheitis and Cyathostoma variegatum causing serious respiratory problems in juveniles.[70]

In the areas in which it was endemic, the emu was an important source of meat to Aboriginal Australians. They used the fat as bush medicine and rubbed it into their skin. It served as a valuable lubricant, was used to oil wooden tools and utensils such as the coolamon, and was mixed with ochre to make the traditional paint for ceremonial body adornment.[75] Their eggs were also foraged for food.[76]

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

Emus are around all the time, in green times and dry times. You pluck the feathers out first, then pull out the crop from the stomach, and put in the feathers you've pulled out, and then singe it on the fire. You wrap the milk guts that you've pulled out into something [such as] gum leaves and cook them. When you've got the fat off, you cut the meat up and cook it on fire made from river red gum wood.[77]

Farmed emu being grain fed

The birds were a food and fuel source for early European settlers, and are now farmed, in Australia and elsewhere, for their meat, oil and leather. Commercial emu farming started in Western Australia around 1970.[78] The commercial industry in the country 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,[79] 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 the leg and digestive problems that arise from inactivity. They are typically fed on grain supplemented by grazing, and are slaughtered at 15 to 18 months.[80]

The Salem district administration in India advised farmers in 2012 not to invest in the emu business which was being heavily promoted at the time; further investigation was needed to assess the profitability of farming the birds in India.[81] In the United States, it was reported in 2013 that many ranchers had left the emu business; it was estimated that the number of growers had dropped from over five thousand in 1998 to one or two thousand in 2013. The remaining growers increasingly rely on sales of oil for their profit, although, leather, eggs, and meat are also sold.[82]

1807 plate showing now extinct island emus taken to France for breeding purposes in 1804

Emus are farmed primarily for their meat, leather, feathers and oil, and 95% of the carcass can be used.[79] Emu meat is a low-fat product (less than 1.5% fat), and 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 US Food and Drug Administration to be a red meat because its red colour and pH value approximate that of beef,[79] but for inspection purposes it is considered to be poultry. Emu fat is rendered to produce oil for cosmetics, dietary supplements, and therapeutic products.[83] The oil is obtained from the subcutaneous and retroperitoneal fat; the macerated adipose tissue is heated and the liquefied fat is filtered to get a clear oil.[83] This consists mainly of fatty acids of which oleic acid (42%), linoleic and palmitic acids (21% each) are the most prominent components.[83] It also contains various anti-oxidants, notably carotenoids and flavones.[83]

There is some evidence that the oil has anti-inflammatory properties;[84] however, there have not yet been extensive tests,[83] and the USDA regards pure emu oil as an unapproved drug and highlighted it in a 2009 article entitled "How to Spot Health Fraud".[85] Nevertheless, the oil has been linked to the easing of gastrointestinal inflammation, and tests on rats have shown that it has a significant effect in treating arthritis and joint pain, more so than olive or fish oils.[86] It has been scientifically shown to improve the rate of wound healing, but the mechanism responsible for this effect is not understood.[86] A 2008 study has claimed that emu oil has a better anti-oxidative and anti-inflammatory potential than ostrich oil, and linked this to emu oil's higher proportion of unsaturated to saturated fatty acids.[84][86][87] 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.[88]

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 items as wallets, handbags, shoes and clothes,[82] often in combination with other leathers. The feathers and eggs are used in decorative arts and crafts. In particular, emptied emu eggs have been engraved with portraits, similar to cameos, and scenes of Australian native animals.[89] Mounted Emu eggs and emu-egg containers in the form of hundreds of goblets, inkstands and vases were produced in the second half of the nineteenth century, all richly embellished with images of Australian flora, fauna and indigenous people by travelling silversmiths, founders of a 'new Australian grammar of ornament'.[90][91] They continued longstanding traditions that can be traced back to the European mounted ostrich eggs of the thirteenth century and Christian symbolism and notions of virginity, fertility, faith and strength. For a society of proud settlers who sought to bring culture and civilisation to their new world, the traditional ostrich-egg goblet, freed from its roots in a society dominated by court culture,[92] was creatively made novel in the Australian colonies as forms and functions were invented to make the objects attractive to a new, broader audience.[93] Significant designers Adolphus Blau, Julius Hogarth, Ernest Leviny, Julius Schomburgk, Johann Heinrich Steiner, Christian Quist, Joachim Matthias Wendt, William Edwards and others[94][95] had the technical training on which to build flourishing businesses in a country rich in raw materials and a clientele hungry for old-world paraphernalia.[96]

Top: The "Emu in the sky". In Western astronomy terms, Southern Cross is on the right; Scorpius on the left; the emu's head is the Coalsack.
Bottom right: Coat of Arms of Australia. Bottom left: The emu on a postage stamp of Australia issued in 1942.

The emu has a prominent place in Australian Aboriginal mythology, including a creation myth of the Yuwaalaraay and other groups in New South Wales 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.[97] 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.[98] 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 in the sky.[99][100] Several of the Sydney rock engravings depict emus,[101] and the birds are mimicked in Indigenous dances.[102] Hunting emus, known as kari in the Kaurna language, features in the major Dreaming story of the Kaurna people of the Adelaide region about the ancestor hero Tjilbruke.

The emu is popularly but unofficially considered as a faunal emblem – the national bird of Australia.[103][104] 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.[104][105] 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.[106] The hats of the Australian Light Horse are decorated with emu feather plumes.[107][108]

Trademarks of early Australian companies using the emu included Webbenderfer Bros frame mouldings (1891), Mac Robertson Chocolate and Cocoa (1893), Dyason and Son Emu Brand Cordial Sauce (1894), James Allard Pottery Wares (1906), and rope manufacturers G. Kinnear and Sons Pty. Ltd. still use it on some of their products.[109]

There are around six hundred gazetted places in Australia with "emu" in their title, including mountains, lakes, hills, plains, creeks and waterholes.[110] During the 19th and 20th centuries, many Australian companies and household products were named after the bird. In Western Australia, Emu beer has been produced since the early 20th century and the Swan Brewery continues to produce a range of beers branded as "Emu".[111] The quarterly peer-reviewed journal of the Royal Australasian Ornithologists Union, also known as Birds Australia, is entitled Emu: Austral Ornithology.[112]

The comedian Rod Hull featured a wayward emu puppet in his act for many years and the bird returned to the small screen in the hands of his son after the puppeteer's death in 1999.[113] In 2019, American insurance company Liberty Mutual launched an advertising campaign that features LiMu Emu, a CGI-rendered emu.[114]