# Is this a Half-sider Cockatiel?



## babuvt (Aug 27, 2012)

Hi,
I recently acquired a Cockatiel which has cheek patch on one side and none on other side.
Is this due to a genetic glitch or half-sider or can be a mutation? :grey tiel:


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## thewandererw (Aug 22, 2011)

I have not heard of this in cockatiels but have in budgies were they are split down the middle with two different mutations


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## Darkel777 (Jun 7, 2013)

I would say it is split pied and the white spot on the side of its head is a tick mark. Other than that, it is a pearl, likely a hen if older than 6 months. There is no "halfsider" mutation in cockatiels.


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## toxic00angel (Aug 28, 2014)

Would be cool if it was a halfsider (something new for the cockatiel world) but if it was, there would be no yellow colouring on that whole side of the body, but there is yellow on its wing. What a cutie though.


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## Peetenomax (Nov 23, 2013)

What you have there is a very rare bird.
It's known as Chimera

In the simplest terms it occurs when 2 eggs merge or something. 
Here's a cardinal that is also one but it's both male & female

*edit. I should say that it appears to be a Chimera


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## Darkel777 (Jun 7, 2013)

Chimerism occurs when a hen deposits two embryos in a single egg during rapid egg laying and the two embryos are similar enough to merge and become a single organism.

I don't believe that is what is going on here, a tick mark would be a simpler explaination. Take feathers from the white spot and from the normal looking areas to be sex tested for confirmation. If it is a chimera, the white spot will be male dna and the rest will be female.


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## Vickitiel (Oct 10, 2012)

That's really cool! What a unique 'tiel


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## yokobirdie (Jul 9, 2014)

I have no experience with genetics, but your 'tiel is gorgeous!


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## Tequilagirl (Mar 4, 2013)

What a special bird! Love her!


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## RachelD (Aug 30, 2014)

What an unique tiel! I love her


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## SoCalTiels (Oct 8, 2013)

No clue on the genetics but it's such a curiosity, I understand chimerism in cats previously. Would love to learn more if find anything out. Its just so odd seeing a white face with some color to the shoulder shoulder and crest, crazier even to think it's an entirely different looking bird in the other side.


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## Pippitha (Mar 27, 2011)

That's really cool. It might be a chimera, but you'd have to DNA test both sides to find out. Or it might just be a really neat color mutation. Either way, I'd love to have a bird like that


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## tielfan (Aug 31, 2008)

I would guess a genetic mosaic rather than a chimera/halfsider. The coloring looks pretty even on both sides of the body except for the cheek. It's not a pied tickmark because pied doesn't affect the orange cheek patch.

A chimera is when two different individuals (non-identical twins) have merged into a single individual. A genetic mosaic is when only one individual is involved, but the DNA in one or more areas of the body got changed somehow during embryonic development and is different from the rest of the body. I have a huge article about 'mixed DNA' at http://www.littlefeatheredbuddies.com/info/breed-schimmel.html If you'd like for your bird's pictures to appear in this article, please let me know. It would be an interesting addition.

Halfsiders can occur in any species. It's a genetic anomaly not a true mutation, and halfsider birds who are able to reproduce have normal-colored babies. I haven't seen any pictures of "split down the middle" cockatiels but it could happen. I've seen several examples of "tricolor" cockatiels, which is apparently some kind of mixed DNA situation. The tricolor phenomenon is what my article is really about.


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## Janalee (Jul 25, 2012)

*half-sider*

Wow, that is amazing! It almost looks like 2 different birds. How unique and beautiful!


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## SilverSage (Oct 19, 2014)

I must admit this fascinates me. I would love to hear a definitive answer here


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