Every year we see posts on social media of people trying to sex their emu by their head markings, so here is a post to have a look at the truth in this theory. 

The theory quite simply states that if an emu chick has a bullseye feather pattern on it's head then it is male, without the bullseye, females. 

Lets look at this below for the emu who were used. The conclusion stats are at the bottom of the page.​

27 emu were recorded
10 proved the theory works - 4 males with a bullseye, 6 females without
13 proved the theory doesn't work - 7 males without a bullseye, 6 females with a bullseye
4 were inconclusive or had no DNA result

In order for this bullseye theory to be correct, all the results should correspond to the theory and 13 out of 27 did not. Proving that the bullseye theory of sexing is an unreliable method of sexing emu chicks.
​However, trying to sex them by their head patterns is always a bit of fun whilst waiting for the DNA results. 

Thanks go to Alex Walker for the article. 

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​OK, I’ve read several posts lately in different Emu groups about the hatching process of Emu, it’s probably the only time that we humans think we can interfere to "help", either by drilling small holes in the air cell end of the shell or breaking away parts of the shell to “assist" the baby chick get out. Therefore, I thought I’d go through the actual process of a baby Emu (or other chick) hatching.

Depending on the species, the chick will orientate itself in the hatching position a few days before hatching. To do this the chick wriggles around inside the shell and gets its head under its left wing. At the same time this is happening the egg shell which is made up of three layers of crystalline calcium with minerals in a Nano structure is being dissolved, from the inside out by a protein called 'osteopontin' which takes this calcium into the membrane surrounding the chick and through that, into the chicks bloodstream. The calcium is then absorbed into the chicks skeleton strengthening the chicks bones, like you taking calcium tablets! This process weakens the shell layers from the inside out making pipping and hatching easier.

The membrane called the chorioallantois has been allowing the chick to inhale oxygen from outside, and exhale carbon dioxide from the chick through the shell pores (the lighter coloured specs on the eggs). This membrane is full of tiny blood vessels that transport the oxygen through the shell and into the chick. A couple of days before hatching (in Emu), the chick breaks through the internal wall into the air cell end of the egg (internally pips), and starts breathing air through its lungs, as well as still being attached to the membrane via an umbilicus.

At the same time a muscle on the back of the chicks neck enlarges several times it original size to form a 'pipping muscle'. The chick then continues to breathe the air in the air cell whilst getting ready for the big push. At the same time the movements inside the shell are helping the yolk sac to be absorbed into the abdomen, sometimes this is only complete right before hatching.

As the air in the air cell gets used up the chick starts to 'suffocate', oxygen is running out and carbon dioxide levels in its blood increase dramatically, this TRIGGERS the pipping muscle which will involuntary to go into spasm, it starts to flex causing the beak to strike the weakened shell from the inside. When the spasms become strong enough the chick breaks through the three layers of shell into the big wide world and can take a breath of fresh air and recover from a very traumatic (near death) experience. After resting, sometimes for several hours, it continues to enlarge the hole, and it’s struggles help the last remaining yolk sac to be absorbed. Only towards the end of hatching does it detach itself from the membrane that is full of blood vessels.

For the above reasons you can see why - 1) You shouldn’t interfere by drilling holes in the shell. 2) You shouldn’t start breaking bits of shell away to make the hole bigger as you risk breaking a blood vessel and causing the chick to bleed to death.
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