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Emu run through

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Professor Graeme Martin, from the University of Western Australia’s Institute of Agriculture, brings us up to speed with the emu.
There was a lot of interest in the idea of emu farming in the late 1980s and early 1990s. It was quickly realised they were very suitable for farming but there none of the detailed biology that any emu farmer would need. So investigations began into basic science of how they reproduced and what controlled that reproduction. Professor Martin's group teamed up with a group from the Western Australia Department of Agriculture who were looking at nutrition.
Emus belong to a group of birds called ratites, such as the ostrich, the cassowary, the rhea and the kiwi. They are all birds that don’t fly and don’t develop adult flight feathers, instead retaining their chick feathers. The fluffy, downy feathers provide good insulation from heat and cold. 

Emu feathers are dual feathers with a special characteristic: halfway along they branch, forming a Y shape with the point going into the skin. Unlike birds that fly, emus have thick, heavy bones to carry their large bodies. Emu wings are tiny, vestigial things. Ratites evolved separately in different parts of the world they evolved parallel. DNA studies show that you have to go a very long way back in time to find a common ancestor. While most birds have four toes, ostriches only have two whereas emus and cassowaries have three and have prodigiously sharp claws.
Emus use their feet in defence so Professor Martins’ team wore cricket pads when working with them. Emus are very curious birds and use their substantial beaks for investigation but rarely for attack.
Emus form pair bonds, in which the male and female form a partnership that develops very early in the breeding season. This caused two problems for emu farmers. 
All weather wanderers - emu on highway near Thredbo during the recent sudden cold snap (K Forsstrom 24 June 2016)

The first problem is the cost of feeding a lot of males – this is why livestock farmers generally prefer to keep primarily female stock and a minimum number of males. The second problem with pair bonding is that, unlike sheep and cattle, the farmer could not breed an elite male with a large number of females to improve the genetics of the stock. The solution to both problems is artificial insemination. A colleague of Professor Martin, Irek Malecki, developed emu artificial insemination (a world first) and then moved on to the ostrich, a truly terrifying bird. 

The emu is another Australian bird where the female takes no part in incubating the eggs or raising the young. Before the start of the breeding season, a male emu eats large amounts of food, storing up fat in a massive pad around his tail. When the laying season starts (May to June), the male makes a “nest” by scratching together a few twigs and pebbles and the female lays an egg in this structure every 2-3 days for about three weeks. 
Above: Irek Malecki collecting emu semen. The yellow raincoat is to prevent pecking injuries. (image from Graeme Martin)
Emu nest By IKAl - Own work, CC BY-SA 2.5, https://commons.wikimedia.org/w/index.php?curid=2098930 egg nest

The female holds the male’s sperm in her reproductive tract allowing her to fertilise several successive eggs after each mating. When there are 7-8 eggs in the nest, the male sits on the eggs to incubate them. He immediately loses his mating drive because his testosterone disappears. However, as the days pass, the female tends to wander away and may mate with other males, returning to the nest mainly to lay these eggs, this time from different partners, in the growing clutch. The male will not eat, drink or get up for the next 54 days, going into a kind of stupor. 

During this period, he metabolises the fat he had stored and it looks as though this leads to ketosis, making him dopey. In that state, researchers can go to a nest and lift up the emu to look at the eggs without arousing any aggression. The eggs all eventually hatch, most within a day. The male then drinks litres of water and eats massive amounts of food. In the bush, he will look after the chicks for 18 months so may miss a complete breeding season as a consequence. The chicks grow up and become sexually mature but without gaining obvious adult characteristics (such as adult feathers), a phenomenon known as ‘neoteny’. 
Below: Irek Malecki checking for eggs under a male emu (image from Graeme Martin)

Emus can move the start of egg-laying by several weeks in response to rainfall patterns such as thunderstorms a month before the start of the breeding season where they can somehow advance egg-laying.
In the wild emus rarely form large groups and are nomadic rather than migratory. Studies by CSIRO Emu Guru, Stephen Davies showed emus moved up to 1300km in a year, apparently migrating towards clouds on the horizon where it might be raining. By the time they reach their destination, there would be fresh plant growth and more insects, both foods for omniverous emus. 

Cuddling an emu: Dr Judy van Cleeff demonstrating how calm the farm bred emus can become.(image from Graeme Martin)
In emu farming, the eggs would not be incubated in nests but in artificial incubators. When the eggs hatch, the chicks imprint on humans and become quite friendly, even letting people cuddle them. This human imprinting also makes artificial insemination much easier, especially getting sperm from males.
Emus and ostriches love to run and can run faster than humans. They are such fast runners that even cats and foxes don’t do them much damage. Sports scientists wanted to know how the big birds can run so fast and so put them on treadmills so they can study the mechanics of their limbs. The birds seems to love this … they would happily run for hours and seemed reluctant to leave at the end of the sessions. The emu is a truly remarkable native bird as evidenced by this emu run-through

Professor Graeme Martin was interviewed for A Question of Balance by Ruby Vincent. Summary text by Victor Barry June 2016.

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