The Lutino Cockatiel mutation is
sex-linked recessiveand is one that seems to stand out from the crowd.
It's bright yellow colour devoid of all dark contrast except for the orange
cheekpatch make them a striking looking bird. Also the presence of the red eye
instead of the normal dark colour give it a unique look. Lutino can be combined
readily with the pearl, pied, cinnamon and whiteface mutations to further
enhance the beauty of this colour. Lutino Cockatiels are a colour that makes visual
sexing of the bird very difficult and the subtle differences between the sexes can
often be nigh on impossible to distinguish.
One negative trait of lutino cockatiels has been a bald patch which
is apparent behind the crest area on the head. Fortunately with successful
selective breeding practices this trait is being reduced. There are some
magnificent specimens around now that have total feather coverage of the head.
The lutino gene is called a sex-linked recessive gene. It is
one that affects the grey family of pigments in birds and is one of the easiest
to recognise. Basically this gene successfully prevents the production of grey
colours or 'melanin'. So if you imagine a normal grey cockatiel that has all the
grey washed out or taken away then you will see a lutino.
lutino gene in birds is the equivalent of the Albino gene in mammals. In mammals
this gene leaves a white creature with red eyes because the melanin has been
removed. In the lutino the same effect has taken place. The reason we don't get
a white bird from the lutino gene is because birds do not just have one form of
pigment, ie melanin, as mammals do. Birds have grey family pigments (melanin)
and yellow family pigments (psittacins). To get a white bird both these pigments
need to be removed and there is no one gene that is capable of doing that.
Having said this though it is possible to get a white bird by the combining of
the lutino gene that removes the melanin and the blue or whiteface gene that
removes the yellow. Thus the albino cockatiel is genetically a Whiteface
Now we get down to the technical part of inheritance, or how
a bird can be a lutino cockatiel and what does it need from what parent. This is where the
term sex-linked recessive needs to be explained.
As most people know in humans, each person basically contains
pairs of chromosomes that hold all the information that make us what we look
like. To determine the sex of a human child each baby has a pair of chromosomes
that are either XX (female) or XY (male). In birds this is the opposite way around
so it is the female that has the XY combination and thus it is her that
determines what sex each chick will be. So basically it gets down to the point
that the cock bird carries two 'X' chromosomes while the hen has only one.
The lutino gene is one that is carried on the sex chromosome
or X. The Y that the hen contains as her second one is too short to carry any
wild-type genes that would suppress or oppose those carried on the X. Thus
if the X chromosome contains the lutino gene in a hen, she will be a visual
lutino bird because she has no gene on her Y chromosome to dominate over the
lutino. In a cock bird though because he has two 'X' chromosomes if he has only a
lutino gene on one of them then he will have a wild-type or normal gene on the
other that would prohibit the lutino from being visible. If he had a lutino gene
on both X's then there is nothing to prohibit it from being visible and the bird
would thus be lutino. I hope I still have you with me at this point!
So when we have two birds making babies each parent will give
either one of their two sex chromosomes to a chick. The male has only two 'X's so he
will give one of them whereas the hen could give either an X or a Y. Because the
lutino gene is carried on the X, any chick from a visual lutino father will get
a lutino gene. With the hen having an X and a Y she could pass on either but
remember only the X holds the lutino. So if she passes the X to a chick it will
have an X from mum and an X from dad and so will be an XX and thus a boy. If the
mother passes the Y gene the chick will have an X from dad and the Y from mum
and be a girl.
From this we should see that only a chick that gets an X
chromosome from mum can inherit any sex-linked genes from her as the Y contains
none. So it is impossible for a hen to pass any of these on to any female chick
So we have a scenario where we have a lutino hen and a normal
grey male. Dad will give each chick a normal gene and mum will give her sons the
X that contains the lutino gene and her daughters the Y that contain no genes.
Thus each male chick will have a normal gene and a lutino gene. The lutino is
opposed by the normal and thus called recessive and will not show up
visually. He will be then termed 'split lutino'. He can then give any of his
chicks either a lutino or a normal and if he gives the lutino to a daughter then
she will be visual lutino.
Both of these chicks I know are definitely hens
because mum was not a Lutino and dad
was only split Lutino.
I hope this makes sense. If you have any questions please
feel free to email me and I will help wherever I can.