BASIC COCKATIEL GENETICS

By Jennifer Jones

 

 

 

At the start of the breeding season, we are usually full of anticipation as to the quality of the youngsters we will breed. Most of us are probably hoping to breed the ‘perfect’ cockatiel or at least something unusual. When we pair our birds, it is helpful to have at least a little knowledge of cockatiel genetics, otherwise those beautiful mutation birds that we have paired may only produce an abundance of normal greys, and it is for this reason that I am going to try to outline a few basic rules that may help to avoid this problem. Because I have always close rung all the many hundreds of cockatiels I have bred and kept careful records; I now have at least a good working knowledge. The subject of genetics is difficult to understand, and I have realised since attempting to write this article, that it is also a difficult subject to write about.

 

Most of the straightforward mutations we see today are either sex-linked or recessive, and these are as follows:

 

Sex Linked (S-L)  Recessive (R)

 

Lutino  Whitefaced

Cinnamon  Pied

Pearl  Fallow

Yellow-cheek   Pastel Face

 

We then have combination mutations such as the classic example:

 

  Whitefaced (R) Cinnamon (S-L) Pearl (S-L) Pied (R)

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SEX LINKED MUTATIONS

 

A fertile egg will have received half its chromosomes from the father and half from the mother, and these chromosomes carry the genes that determine the sex and appearance of the future fledgling. The first basic rule that we need to know is that a male cockatiel has two X chromosomes (XX), and a female has one X and one Y (XY). The Y chromosome determines the female’s sex. The X chromosomes carry the genes responsible for sex-linked mutations Cinnamon, Lutino, Pearl and Yellow-Cheek. For a male cockatiel to be a visual sex-linked mutation (Lutino, for example), it must carry the gene responsible for it on both X chromosomes. If it carries the gene for Lutino on only one of its X chromosomes, the dominant normal will mask that mutation, and the cock bird will be a normal grey in appearance but split for Lutino. There is no colour gene present on the female Y chromosome, and if the gene responsible for Lutino is carried on its only X chromosome, it will always be Lutino in appearance.

 

I am going to use Lutino as an example, but whatever other sex-linked mutation we aim to breed, Pearl, Cinnamon or Yellow cheek, the following rules apply:

 

A cock can either be visually a Lutino or split for Lutino (that means it carries the gene responsible unseen and can pass this mutation on to its youngsters). A hen cannot be split for a sex-linked mutation – it must be a visual Lutino before it can pass this mutation on to its male offspring.

 

For a cock to be visually Lutino, it must inherit two of the genes responsible for this mutation, one from its father and one from its mother – the mother would have to be visually that mutation, but the father could be either a visual Lutino or a split for Lutino.

 

When a Lutino cock bird (or split for Lutino) is paired to any other mutation (a normal grey hen, for example), any Lutino youngsters in the nest will always be hens.

 

A cock can carry unseen any of the sex-linked mutations on its X chromosomes and can pass them on to its offspring. These are passed on randomly, making it a matter of chance as to which of the splits will be inherited by a particular youngster.

 

Example Pairing

 

Normal Grey Cock split Lutino, Cinnamon-Pearl x Lutino Hen – will produce

 

Lutino Cocks (these are produced because the youngster will have received the gene responsible for Lutino from both its mother and father)

Lutino Hens

Cinnamon-Pearl Hens

Normal Grey Cocks split Lutino

Normal Grey Cocks split Cinnamon-Pearl

Normal Grey Hens

 

To take this example pairing one step further: If the hen used is a normal grey (it cannot be split for sex-linked mutations), all sex-linked mutations appearing in the nest will be hens. All the cock birds produced will be normal grey in appearance, and each will inherit a split for a sex-linked mutation from their father, but it will be a matter of chance as to which split has been passed on to these young cock birds.

 

SIMPLE RECESSIVE MUTATIONS

 

Recessive mutations, Pied, Fallow and Whiteface, are recessive to the dominant Normal Grey, and, unlike sex-linked mutations, they have nothing to do with the sex of the cockatiel. The genes responsible for these mutations are located on the chromosomes known as autosomes, and it is important to remember that cocks and hens can be split for recessive mutations. To produce a cockatiel of either sex that is visually a recessive mutation (for example, Pied), it must have two of the genes responsible for its genetic makeup (one inherited from the father and one from the mother). If there is only one recessive gene present in the makeup of the cockatiel, the bird is split for that mutation. Except for Pied, cockatiels split for recessive mutations give no indication of being a split in their appearance. Indications that male and female cockatiels are split for pied range from large patches to one or two single white or yellow feathers on the back of the head, and sometimes it can be just one pink toe or toenail.

 

Example Pairings

 

I will combine the sex-linked mutation Lutino with recessive mutations in the following examples, but you can substitute Cinnamon, Pearl or Yellow-cheek for this mutation. You will notice that the first two examples illustrate pairings that produce too many greys. Occasionally, breeders will deliberately pair birds in this way to produce quality split birds that are essential to improve the size, head quality, depth of colour, etc., in a breeding programme.

 

Pied Cock  x  Lutino Hen – will produce   Whiteface Cock  x  Lutino Hen – will produce

 

Normal Cocks split Pied and Lutino  Normal Cocks split Whiteface and Lutino

Normal Hens split Pied  Normal Hens split Whiteface

 

Lutino Cock  x  Pied Hen – will produce  Lutino Cock  x  Whiteface Hen – will produce

 

Normal Cocks split Pied and Lutino  Normal Cocks split Whiteface and Lutino

Lutino Hens split pied  Lutino Hens split Whiteface

 

Pied Cock  x  Lutino split Pied Hen - will  Lutino split Pied Cock  x  Pied Hen - will

produce  produce

 

Normal Cocks split Pied and Lutino  Normal Cocks split Pied and Lutino

Pied Cocks split Lutino  Pied Cocks split Lutino

Normal Hens split Pied  Lutino Pied Hens

Pied Hens  Lutino Hens split Pied

 

Whiteface Cock  x  Lutino split  Lutino Cock split Whiteface  x  Whiteface Hen -

Whiteface Hen – will produce   will produce

 

Whiteface Cocks split Lutino  Whiteface Cocks split Lutino

Normal Cocks split Whiteface and Lutino  Normal Cocks split Whiteface and Lutino

Whiteface Hens  Albino Hens

Normal Hens split Whiteface  Lutino split Whiteface Hens

 

DOMINANT SILVER

 

Dominant Silver is the only mutation known to be equally as dominant as the Normal Grey. It exists in Single Factor (SF) and Double Factor (DF) and, as with recessive mutations, it has nothing to do with the sex of the cockatiel. Dominant Silver offspring can be bred in the first generation from a Dominant Silver Cock or Hen. As this is a dominant mutation, non-visual cocks and hens cannot be split for Dominant Silver.

 

Example Pairings

 

Dominant Silver (DF) Cock or Hen  x  Normal Grey Cock or Hen – will produce

 

Dominant Silver (SF) Cocks and Hens

 

Dominant Silver (SF) Cock or Hen x  Normal Grey Cock or Hen – will produce

 

50% Dominant Silver (SF) Cocks and Hens

50% Normal Cocks and Hens

 

Dominant Silver (SF) Cock or Hen  x  Dominant Silver (SF) – will produce

 

25% Normal Cocks and Hens

50% Dominant Silver (SF) Cocks and Hens

25% Dominant Silver (DF) Cocks and Hens

 

It is difficult to separate Normal from Dominant Silver in the nest as the adult colouration appears at the first moult. In adults, the silver is darker around the base of the neck, extending up onto the head. The eyes, beak and legs are black. The DF Dominant Silver is a further dilution of the silver grey, giving an almost yellowish-white colour on the wings and tail feathers.

 

 

PASTEL FACE

 

The gene responsible for Pastel Face is autosomal rather than sex-linked, and both males and females can be split for this mutation. It is recessive to all mutations except Whiteface when it becomes Dominant; therefore, a Whiteface cockatiel cannot carry Pastel Face. If Pastel Face is bred with any other mutation, all offspring will be split to Pastel Face.

 

Example Pairings

 

Pastel Face Cock or Hen  x  Normal – will produce

 

Normal Cocks and Hens split Pastel Face

 

Pastel Face split Whiteface Cock or Hen  x  Whiteface – will produce

 

50% Pastel Face split Whiteface

50% Whiteface

 

Normal split Pastel Face Cock or Hen  x  Whiteface – will produce

 

50% Pastel Face split Whiteface

50% Normal split Whiteface

 

Pastel Face split Whiteface Cock Hen  x  Pastel Face split Whiteface – will produce

 

25% Pastel Face

50% Pastel Face split Whiteface

25% Whiteface

 

Pastel Face Cock or Hen  x  Whiteface – will  produce

 

100% Pastel Face split Whiteface

 

 

COMBINATION MUTATIONS

 

Once you have learned the basics of cockatiel genetics, it is easy to breed your own combination mutations. It takes a little longer, and you must plan in advance, but if you already have some excellent Primrose Pied, for example, and want to breed Whiteface Pied, it is easy to introduce the Whiteface gene using other birds of this mutation that you already own. It is very satisfying to create your own mutation cockatiels rather than having to go out and buy them. In my opinion, this is the best way to breed top-quality birds for the show bench, as you will already know the strengths and weaknesses of your own birds.