Emu

Characteristics

Emus are large flightless birds. They have large, feathered bodies, strong legs, and a long and sparsely feathered neck. They are the second largest bird in the world, surpassed only by the ostrich. Emus do have small wings, but they are insufficient for flight. Emus and other ratites have a unique feather design. Each feather is double-shafted and lacks barbules, resulting in the barbs hanging loosely and appearing similar to hair from a distance. New feathers after a molt are almost black in color but fade to grayish brown and even near cream in the Australian sun.

Species Specifics

There is only one extant species of emu. Emus have a similar physical appearance to ostriches but emus have a longer, lower profile and have 3 toes on each foot (ostriches have only 2 toes).

Physical Characteristics

Emus have very strong legs which allow them to defend themselves from dingoes, one of their main predators. They can leap quickly to remove their neck from the predator's reach, and the can kick with a lethal strength.Emus are able to store large amounts of fat on their bodies. They can lose up to half of their body mass during periods of starvation, allowing them to survive weeks without food such as when the male is incubating his eggs.

Ecology

Habitat

Grassy plains and dry open forests

Distribution

Widespread throughout mainland Australia

Diet

Fruits, flowers, insects, seeds, and grass. Emus are known to especially enjoy caterpillars and grasshoppers. They also swallow small stones that aid in the digestion process.

Ecological Web

While emus are classified as omnivores, their diet leans heavily toward plants. Many seeds they eat are ingested whole, and expelled the same way. This makes them important seed dispersers. Adult emus have few natural predators due to their size and speed. Dingoes occasionally target emus but are defended against with a strong kick ending in sharp claws. They can also avoid airborne predators such as the Wedge-tailed Eagle but running swiftly and constantly changing directions. Emu chicks face much larger threats from animals such as raptors, monitor lizards, foxes, cats, and dogs. For this reason the male emu will protect his young for up to 2 years.

Activity and Behavior

Activity Pattern

Emus are strictly diurnal but wake often during the night due to predatory threats, hydration needs, or to defecate.

Behavior

While emus are generally solitary, they will form social groups when it is advantageous to their survival. For example, large groups of emus will migrate together toward new food sources.

Social Behavior

Most often found individually, but will form large temporary groups for migration or cooperative feeding.

Reproductive Behavior

Emus form breeding pairs in December or January and stay together for approximately five months, until the female lays her eggs in May or June. The male will build the nest (which sits on the ground) into which the female will lay 5 to 15 dark green eggs over several days. Once she is finished laying her eggs the female will wander off and leave the male to incubate them, sometimes mating with another male and laying another clutch of eggs in his nest. The male will sit on the nest for 8 weeks, getting up only to turn the eggs and tidy the next. He does not eat, drink, or defecate while incubating his eggs, and he will lose up to one-third of his body weight during this time.

Offspring

5-15 chicks; average weight at hatching is 1.1 pound. Parental care (father only) for 18 months.

Conservation

Status

The emu population in considered stable and they are not listed as endangered or threatened. Emu distribution on the Australian mainland has been affected by human activities- the species used to be common along Australia's east coast but rapid human development has forced them out of this area. However, agricultural development and water provided for livestock in Australia's Outback have allowed the emu to expand its range to areas that were previously too dry for its survival.

Historical

There was a subspecies of emu restricted the island of Tasmania. This subspecies went extinct around 1865, following the arrival of Europeans.

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