Sex-linked Genes

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“How do you know the sex of that chick?”

I post a lot of chick pics and videos on my Facebook page. Many times I will identify a chick as male or female, sometimes as soon as it has hatched, and I inevitably receive this question. The answer is sex-linked genes.

I strongly recommend checking out my more in-depth article on bird genetics before delving in here. This article is a more cursory look at sex-linked genes.

What is a sex-linked gene?

To understand sex-linked genes, you have to understand sex chromosomes. Humans have two: X and Y. In general*, females are born with XX and males are born with XY. Birds use a different system: males are ZZ and females are ZW.

Sex-linked genes reside on sex chromosomes. If you have a gene sitting on the Z chromosome and that bird is a female, there is no corresponding Z chromosome to block out the gene. It will be expressed.

Look at this punnet square of two birds. Visually, both male and female in this pair look normal. However, the male carries a sex-linked gene (shown here in orange) on one of his Z chromosomes. It’s hidden by the fact that he has a corresponding Z chromosome without the gene.

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Punnet square of a male carrying a sex-linked gene and a normal hen.

The squares in the middle show you their babies. On the right, you have a normal male (ZZ) and normal female (ZW):

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normal birds, both sexes

On the left, you’ll see that half their babies carry the sex-linked gene. One, the male (ZZ) will look like his father. He will carry the gene without expressing it (this is known as “split”).

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male bird carrying sex-linked gene

The female (ZW) has no corresponding Z to counter the Z chromosome carrying the gene. She will VISUALLY show the gene.

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females with sex-linked gene

Females cannot be split to sex-linked genes because they have no corresponding Z chromosome to block it out.

This makes it incredibly easy to sex babies in the nest, so long as you know the genetics of the parents.

Which genes are sex-linked?

This list is not exhaustive, but here are the most common. Sometimes mutations have different names depending on the species. For instance, in green cheek conures, opaline/pearl is called “yellow-sided.”

  • Cinnamon
  • Lutino/Ino
  • opaline (pearl in cockatiels, yellow-sided in green cheek conures)
  • pallid
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This cockatiel has two sex-linked genes: cinnamon and pearl.

If neither parent is visual for the gene, any baby showing the sex-linked gene is FEMALE. This also tells you that dad carries a copy of the gene. It cannot come from mom (if she had the gene, you’d see it). If dad is visual for a sex-linked gene and mom is NOT, then ALL visual babies will be female and ALL normal babies will be male.

Rules for Sexing by Sex-Linked Genes:

  1. If normal male + normal female –> ALL sex-linked babies female, normal babies can be either sex
  2. If visual male + normal female –> ALL sex-linked babies female, ALL normal babies male
  3. If normal male + visual female –> can’t sex, but males will carry the gene
  4. If visual male + visual female –> can’t sex, all babies will carry the gene

These rules only apply for the SAME sex-linked mutation (birds can have multiple sex-linked mutations). So if dad is cinnamon and mom is pearl, you can use rule #2 to sex cinnamon babies, but pearl falls under rule #3 (can’t be sexed).

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Whiteface male split to cinnamon and whiteface pearl female.

I have a pair of cockatiels (above) where the male is whiteface and the female is whiteface pearl. Every so often I get a cinnamon whiteface baby. These chicks will always be female (see rule #1) and it means dad carries the gene for cinnamon. Males produced by this pair will always carry the gene for pearl (rule #3).

In some cases, you can sex as soon as the chicks hatch. Cinnamon, lutino, and pallid all create lighter-colored eyes. The chicks below are the product of a visual pallid male and a violet female. Pallid is sex-linked, and since the mom is not pallid, we can sex all the offspring using rule #2. All pallids from this pair will be female (hatching with red eyes) and all “normal” (blue or violet) babies will be male (hatching with dark eyes).

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Two ringneck chicks, one with red eyes (pallid) an done with dark eyes (normal).

Knowing how to sex with this method saves time and money, as you won’t have to wait for birds to molt into adult colors or send out for DNA testing. It’s also more accurate. But you have to know the mutations of your birds.

Rules for Sexing Sex-linked Genes

*Chromosomal anomalies do exist. People can be born with extra chromosomes (sometimes lots of them!) and outward biology does not always match internal chromosomes. Nature is nothing if not complicated.

This article and all of its images are ©2020 by Karen Trinkaus and may not be reprinted or used in any way without the author’s permission.

Indian Ringneck Colors

These are some of the colors we produce. All of these are babies from previous seasons. Ringnecks are seasonal breeders, so we have a limited quantity each year. In 2020 we should be able to get cinnamon, green, lutino, and albino as well. Please check here for availability.

blue and violet

Blue (left) and violet (right)

blue pallid

blue pallid (white head with sky blue wash)

grey turquoise

grey turquoise

grey

grey

turquoise2

turquoise

violet pallid

violet pallid (white head with faint lavender wash)

violet

violet

© 2020 by Karen Trinkaus. May not be reprinted or used in any way without the author’s permission.

Care Sheet: Indian Ringneck

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Personality: Playful, inquisitive, intelligent, independent

Experience level required: Moderate

Approximate Lifespan: 30 years

Puberty: 12-18mo

Sexing: Dimorphic. Males develop a ring anywhere from 18mo-3 years. If you want to know before that you must DNA sex your bird. Some colors, like albino, never get a ring.

Vocalizations: They can be loud (see video below).

That said, they usually do not make noise all day every day. Vocalizations are typical in the early morning/late afternoon, if the bird feels separated from the flock, or if it is frightened.

Talking ability: Good. Both sexes talk.

Diet: Standard

Minimum recommended cage size: Ringnecks have long tails that are easily damaged in cages that are too small or cluttered. They need large cages with plenty of clearance for their tails.

Cautions: Ringnecks do not form the same strong pair bonds seen in other species. Most parrots will pair off with a buddy or mate. Ringnecks generally don’t do this outside of the mating season. This can make them seem standoffish. Do not buy a ringneck expecting a cuddly, sociable bird!

After weaning, ringnecks go through a bluffing phase in which they bite and show aggression. It is critical that the owner NOT react to the bites. The first year is critical to ringneck development. They go wild very easily if not consistently and amicably handled during the first year.

Don’t get me wrong, ringnecks make wonderful pets, they just aren’t for everyone. I’ve had to steer many potential clients over to conures because they had unrealistic expectations of what ringnecks are like. They are playful, highly intelligent, and curious. They enjoy spending time with people but can also play well by themselves. The best ambassador bird I ever had- the one I could trust to be pet by children and adults alike- was an Indian ringneck. They require an owner who understands their behavior and is willing to give them a lot of time that first year. With ringnecks, you get out what you put in.