Emu: The National Bird of Australia

Emu is the largest bird of Australia and is the only member of the genus Dromaius. It is also the second largest bird of the world after its ratite relative Ostrich. There are three subspecies of Emu recorded from Australia. It dwells along the mainland of Australia and avoids dense forests, heavily populated and arid areas. Emus are flightless birds with body reaching a height of about 2 meters and covered by brown, soft feathers. Neck and the legs are thin and long. They can travel great distances with a fast speed of about 50 km/h for some distance at a time. They are nomadic and may travel long distances in order to find food. They feed on a variety of plants and insects and can remain without food for many weeks. They also take stones, glass pieces and bits of metals which squash the food material in the digestive system. They drink water at an interval of one or two days and are also known to ingest copious fluids. They are also able to swim in water and are known to follow and watch other animals including humans also. They do not sleep continuously at night but are known to take short sleeps.

They are known to bear nails on their toes which are as sharp as knife and are used for kicking away the predators. Their legs are the strongest among all animals are bearing the potential of ripping metal wires and fences. Eye sight and the hearing power is very well developed in Emus so they can identify a predator easily even in the vicinity. The plumage on an eye keeps on changing according to the surrounding environment and acts as a camouflaging structure. Feathers incubate the body excellently and maintain homeostatic balance of the body. Male and female cannot be identified by the external appearance but on the basis of the loud calls that they produce from their inflatable necks. Mating occurs in May and June and they are not monogamous. Fighting among the males for females is very common. Females are known to mate with more than one male and produce a number of eggs in each season. Both male and female are known to gain weight before mating and most of the act of incubation is performed by the male. The male loses weight during incubation as he does not eat anything during this time. Eggs hatch after eight weeks and are nurtured by fathers. They become full grown in six months and will mate after half a year later. They may live from 10-20 years and are easily preyed by dingos, eagles and hawks. They may jump and kick in order to avoid dingos but can only run when chased by eagles and hawks.

They are hunted for their meat, oil and leather. Emu has lean meat and the oil bears good anti-oxidants but not suitable for humans. It is an important cultural icon of Australia and appears on the coins and on the coat of arms. They are classified in the family Casuariidae with their closest relatives, the cassowaries and in the order of ratites Struthioniformes. The body weight may range between 18-48 kg. The females are larger than males and bear wider rump. They bear vestigial wings measuring 20 cm and r a claw is present at the tip of these wings. The wings stabilize the body of the bird while it is moving. The musculature of the pelvic limbs provides them the power for swift running. There are only three toes in the legs and the number of bones and muscles is also reduced. Only gastrocnemius muscles are present at the back of the legs. Pelvic limb muscles play similar role like that of the flight muscles. While walking they take steps of around 100 cm but during striding the size of the steps may reach up to 275 cm. legs lack feathers and the underneath of the feet is provided with cushioned pads. They have a soft bill for grazing.

The neck of Emus is pale blue and sparsely covered with feathers. They have brown to grey-brown plumage and the shafts and the tips of the feathers are black in colour. The tips are known to absorb solar radiation and the inner plumage is known to provide insulation to the bird. Both the sexes are similar but the penis of the male can be seen clearly when he defecates. Plumage is very much influenced by the environmental conditions. Eyes are protected by the nictitating membranes. These membranes are translucent and secondary eyelids. They have a tracheal pouch which becomes more prominent during the mating season. This is used in courting as well as in communicating. The pouch may be 30 cm long, thin walled and very spacious. The amount of air entering the pouch affects the intensity of the call produced by the bird. Females cry typically louder than that of males. During the hot and sunny days the lungs act as evaporating coolers and avoid alkalosis of blood. The metabolic rate is low in comparison to other ratites. Their calls are made up of loud booming, grunting and drumming that can be heard from a distance of about 2 kilometers.

They dwell in most areas of Australia especially in the sclerophyll forest and savanna woodland and least in the populated areas. They travel in flocks showing typical social behaviour. They spend much of their time in preening their plumage with the help of beaks. They forage in a diurnal pattern. They devour crickets, ladybird beetles, moth larvae, ants and grasshoppers. They are known to form breeding pairs during the months of December and January and remain together for about five months. They make a territory and are known to guard it. Both the sexes attain weight and the females weigh heavier than the males weighing about 48-58 kg. Male loses around 9 kg weight while incubating the eggs. During the mating season the testicles in male become double in size which is under the control of luteinizing hormone and testosterone. Female court the males and attain more attractive physical appearance during the mating season. The plumage in female darkens. When a female finds a suitable mate it looks continuously at him by turning her neck and the rump also faces him. At this time female produces a call. Females are more aggressive for mates and often fight for males.

After mating the male loses appetite and constructs nest on the ground with the help of bark, sticks, grass and leaves. The nest is somewhat flat, spherical and 7 cm tall and provides best insulation to the eggs. The male may also add its feathers to the nest if he is interested. The pair mates every day or in a couple of two days and after each mating the female lays about 11 eggs which are very large, thick shelled and dark green eggs. The shell may be 1 mm thick and the number of eggs laid varies with every rainfall. Eggs may weigh 700-900 grams. Incubation period may be of 56 days. The eggs hatch into precocial young ones which require parental care. Newly hatched chicks are active and can leave the nest after few days. Chicks may become full grown in about 5-6 months and may stay with the family for about 6 months. Males can nurture the chicks for a period of about 7 months.

They are consumed as food by Australian and European settlers. Emu fat was used as bush medicine and was rubbed on the skin. It also served as an excellent lubricant. Emu fat contains low fat and cholesterol about 85 mg/100 g. Emu fat is rendered to produce oil to be used in cosmetics, therapeutic products and dietary supplements. The oil is harvested from the subcutaneous and retroperitoneal fat. The oil is a rich source of fatty acids namely, oleic, linoleic and palmitic acids along with various anti-oxidants like carotenoids and flavones. Researches have shown that the oil also bears anti-inflammatory properties. The leather is used for making wallets, shoes, decorative arts and crafts.

They deserve an important place in the Australian Aboriginal Mythology. Emu is the national bird of Australia.

Navodita Maurice