Bustards and emus

From Tropical Topics newsletter, No. 73 May 2002, produced by Stella Martin from Queensland's Environmental Protection Agency. Click on the PDF to read the whole issue.

Bustards are large birds, over a metre in height with a 2.3 m wingspan, and can be seen striding around grasslands and grassy woodland

Bustards

Australian bustards are very similar to those in Africa, Arabia, India and New Guinea. They are large birds, over a metre in height with a 2.3m wingspan, and can be seen striding around grasslands and grassy woodland. Bustards are nomadic, moving according to food sources. They eat grass, fruit, seeds and large insects as well as mice and reptiles, and are able to survive for long periods without drinking. In north-west Australia they are very fond of moonflowers.

Bustards are generally seen on foot but can fly. If disturbed, they will at first freeze, then walk or run away, finally taking off with a heavy strong flight. At breeding times the male puts on an impressive display. He inflates his throat sac so that his long neck feathers spread out in a fan, droops his wings and, with tail splayed over his back, produces a series of roars. The female rewards his efforts by taking full responsibility for incubation of the eggs, on the ground.

There has been a massive decline in numbers of bustards in the southern states of Australia where flocks of up to 1000 could once be encountered. This has been blamed on a combination of intensive agriculture, the invasion of pastoral land by woody weeds, predation of nests by foxes, pesticides and hunting - they were killed by the thousand from about 1860 until protected in 1935. The presence of cattle, sheep and humans also leads the birds to desert their nests. In the north, they have declined in some places, possibly due to woody weed invasion, but in other areas seem to have benefited from clearing. To see a list of research findings on bustards click here .

Emus

During the breeding season, the female developes a pouch and fluffy feathers on her chest and struts about with the pouch inflated Illustration: Lynda Strahan, Interpretive Birding Bulletin

Emus in the wild are a dramatic sight. Said to reach 70 km per hour at a sprint and able to cruise at about 45 km per hour, they are nomadic travellers, moving according to weather and food supplies. They have been observed moving towards clouds and seem to be able to detect rain from great distances. Records show that they can travel over 900 km in nine months and one journey was clocked at 442 km in just 80 days.

Avoiding thick forest and settled areas, emus are found throughout the rest of the Australian mainland, adapting to various environments and feeding on whatever food they can find — flowers, seeds, shoots, fruits, stems and insects, including grasshoppers when they appear in plagues.They even eat their own faeces to pick up nutrients which didn't get absorbed first time round.

However, when the breeding season approaches emus go off their food. As the days begin to shorten, after the summer solstice on 21–22 December, the skin on the birds' necks becomes a brighter blue. It is the female who calls the shots. She develops a chest, a pouch and bunch of fluffy feathers and struts about with the pouch inflated (see above). This acts as a resonating chamber amplifying her booming call so it can be heard 2 km away. Males grunt in reply. She chooses her male and courts him, chasing away other females who come near.

Emus stretch tall during a confrontation

The female is presumably looking for a mate with stamina. Like cassowaries, male emus do all the incubation and raising of the chicks. His mate simply provides the dark green eggs — up to 20 of them. Weighing 700–900 grams each, this is no inconsiderable contribution on her part.

A male emu becomes obsessed with eggs, or paddy melons, oil filters or stubbies, if he has no eggs to sit on. Once he has a reasonable clutch (about seven eggs) the male can be quite aggressive to his mate, or any other female, if they try to add more eggs. He then squats, incubating the eggs non-stop for 56 days without leaving to feed or drink. Stretching his neck along the ground, he does his best to imitate a rock or pile of vegetation and goes into a state of semi-torpor.

By the end of his ordeal he may have lost up to 25 percent of his body weight but he then has to care for youngsters, herding them with him for up to 18 months. Losses are high, with an average of two chicks surviving to adulthood.

Although numbers of emus are high, they appear to have declined in some areas, particularly inland and northern regions. The reason for this is unclear. Emus are hardy and can survive drought, but they may be affected by pollution, intensive farming, the effect of changed fire regimes on food resources and hunting by farmers protecting their crops. On the plus side, farming has benefited emus by providing artificial watering holes.