Peafowl Genetics 302 - Testing for Genes
While there IS a blood test to determine the sex of your birds (useful for chicks if you want to know early, or young white birds that can't be differentiated), there are currently no tests for color or pattern genes in peafowl. This means that testing must be practical- that is, you breed birds and look at the resulting offspring, to determine what genes the parents do or don't have.
This can be used in several ways! It can help you determine which allele a bird is carrying (as in the case of the leucistic genes), and it can help you avoid genes you don't want (if you're trying to breed X, not a combo of X+Y, if you don't like Y and you have a carrier in your flock), or find hidden genes you do like. It can also help you prove out new mutations.
All of these tests are simple and straightforward in theory. In practice, it will take you space, time, and work, and it can be costly to perform them, since you will have to bring in birds to breed with that you might not necessarily want to keep. You will also need to produce multiple offspring for most of these tests, as they work by percentages, and the larger the pool of results, the higher the chance that the percentages are accurate. If you, for example, breed a split pied to a white and get two offspring and they're both pied, MAYBE your bird is homozygous pied, but maybe the third chick would have been het white instead. A good rule of thumb is to produce 200% of the total number of outcomes possible. If there are four possible outcomes (including if some are the same!), then if you breed 8 offspring, you probably got at least 1 of each outcome.
Testing may not be for everyone, due to the time and effort and cost. Some people just like to own the birds and see what they get. BUT, if you are dedicated to a longer term project, or find yourself with questions you need answered, or maybe a brand new color lands in your lap, it pays to have the knowledge on hand, as you will actually waste much less time and money and space if you know what you're doing.
This can be used in several ways! It can help you determine which allele a bird is carrying (as in the case of the leucistic genes), and it can help you avoid genes you don't want (if you're trying to breed X, not a combo of X+Y, if you don't like Y and you have a carrier in your flock), or find hidden genes you do like. It can also help you prove out new mutations.
All of these tests are simple and straightforward in theory. In practice, it will take you space, time, and work, and it can be costly to perform them, since you will have to bring in birds to breed with that you might not necessarily want to keep. You will also need to produce multiple offspring for most of these tests, as they work by percentages, and the larger the pool of results, the higher the chance that the percentages are accurate. If you, for example, breed a split pied to a white and get two offspring and they're both pied, MAYBE your bird is homozygous pied, but maybe the third chick would have been het white instead. A good rule of thumb is to produce 200% of the total number of outcomes possible. If there are four possible outcomes (including if some are the same!), then if you breed 8 offspring, you probably got at least 1 of each outcome.
Testing may not be for everyone, due to the time and effort and cost. Some people just like to own the birds and see what they get. BUT, if you are dedicated to a longer term project, or find yourself with questions you need answered, or maybe a brand new color lands in your lap, it pays to have the knowledge on hand, as you will actually waste much less time and money and space if you know what you're doing.
Testing for Leucistic Genes
This is probably the most widely-used practical genetics test that people know of and use. Since het white, het pied, and homo pied can all look identical, and indeed can even not show at all in the phenotype, many people test their birds to discover what leucistic gene or genes the bird has.
The test is relatively straightforward; you just have to breed the bird in question to a white bird. The resulting offspring will tell you what leucistic gene(s) the bird in question is carrying.
If the bird in question is carrying white (WT/W), half the offspring will be white, the other half split white.
The test is relatively straightforward; you just have to breed the bird in question to a white bird. The resulting offspring will tell you what leucistic gene(s) the bird in question is carrying.
If the bird in question is carrying white (WT/W), half the offspring will be white, the other half split white.
If the bird in question is carrying pied (WT/p), then half the offspring will be pied, and the other half will be split white.
If the bird in question is homozygous pied (p/p), then all of the offspring will be pied.
Easy enough! This also shows you that if you want to produce all pied offspring, all you need is a dark pied and a white. A lot of folks get frustrated that their pieds produce non-pieds, but in this way, if you want 'em you got 'em!
Testing for Hidden Splits
This one isn't super useful if you're just randomly looking to see if your bird is split to any cool colors, because it requires you to have that cool color on hand to test with, BUT it is helpful if you are working on projects to clean out mutations, and it's used in testing to prove out genetics. Finding out if your blues are clean means you can then use those blues in other kinds of breeding work!
This is even more straightforward than the leucistic test above. If you want to know if a bird does or doesn't have an autosomal recessive color, you breed it to that color. If the bird in question is carrying the gene, then half the offspring will be that color.
This is even more straightforward than the leucistic test above. If you want to know if a bird does or doesn't have an autosomal recessive color, you breed it to that color. If the bird in question is carrying the gene, then half the offspring will be that color.
If you are wondering if your male has a sex-linked split, you actually don't really need to do anything. A male het for a sex-linked recessive will produce that color 50% of the time in his hen offspring (25% of total offspring). However! Some of these do look a lot like each other! Which takes us to our next section.
Testing to Prove Genetics
This section will explain how to prove out established genetics and new morphs, and will help you determine if new morphs are the result of a novel gene or a co-expression of an established gene.
The first thing we'll look out is proving out established genetics that are in question. Let's say that you are trying to breed peach, but you suspect that your bird may actually be cameo. The two mutations do look a lot alike (and no surprise, since cameo is part of peach's genetic makeup), and there are probably multiple breeders out there who are breeding "peach" but actually have a cameo or two in the mix. Some breeders don't know/can't tell the difference, so maybe you got sold a bird and you question what the breeder told you.
If you need to prove out the genes a bird has, it's pretty much the same as above- you are going to breed the bird to a gene you think it has. In the case of co-expressed genes (in this example, peach is cameo + purple), you are going to breed the bird to one of each of its components. As we saw in Genetics 203, breeding cameo to purple produces some blues, regardless of which parent is which, and breeding either component color to peach produces only peach and the component color. So to test, you would breed the "peach" in question to a purple, and if it's peach and not cameo, you should get purple and peach (if the bird in question is a male), or all purple (if the bird in question is a hen)- but importantly, you will get no blues. While you could technically use a cameo, the problem persists of telling the difference between them, so it's easier to use purple.
Here are the two charts from Genetics 203- a male peach in question first/left, and a peach hen in question second/right.
The first thing we'll look out is proving out established genetics that are in question. Let's say that you are trying to breed peach, but you suspect that your bird may actually be cameo. The two mutations do look a lot alike (and no surprise, since cameo is part of peach's genetic makeup), and there are probably multiple breeders out there who are breeding "peach" but actually have a cameo or two in the mix. Some breeders don't know/can't tell the difference, so maybe you got sold a bird and you question what the breeder told you.
If you need to prove out the genes a bird has, it's pretty much the same as above- you are going to breed the bird to a gene you think it has. In the case of co-expressed genes (in this example, peach is cameo + purple), you are going to breed the bird to one of each of its components. As we saw in Genetics 203, breeding cameo to purple produces some blues, regardless of which parent is which, and breeding either component color to peach produces only peach and the component color. So to test, you would breed the "peach" in question to a purple, and if it's peach and not cameo, you should get purple and peach (if the bird in question is a male), or all purple (if the bird in question is a hen)- but importantly, you will get no blues. While you could technically use a cameo, the problem persists of telling the difference between them, so it's easier to use purple.
Here are the two charts from Genetics 203- a male peach in question first/left, and a peach hen in question second/right.
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If the bird in question was actually cameo, you would get results like this instead:
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This difference allows you to make SURE that your bird is peach, and NOT cameo (or the other way around!), so if you are trying to do a project with peach, you can found it on actually peach birds.
The other co-expression morphs will act similarly if the cock is the one in question, because he will produce the same spread of offspring (his hens will be his color, his sons will be the mother's color, OR you will get blues in the mix). However, since peach is the only dual-sex-linked color, if the hen is the bird in question, you will simply get 100% blue offspring.
For example, if you weren't sure your bird was indigo instead of a sun-bleached purple, you could breed the bird to a bronze. If the bird is indigo and not purple, you would get an offspring spread like this:
The other co-expression morphs will act similarly if the cock is the one in question, because he will produce the same spread of offspring (his hens will be his color, his sons will be the mother's color, OR you will get blues in the mix). However, since peach is the only dual-sex-linked color, if the hen is the bird in question, you will simply get 100% blue offspring.
For example, if you weren't sure your bird was indigo instead of a sun-bleached purple, you could breed the bird to a bronze. If the bird is indigo and not purple, you would get an offspring spread like this:
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Which at a glance the above looks the same as with peach- you get the mother's color and/or the father's color. Except! It will be different if a hen bird is NOT the combination color. In this example, if she is purple instead of indigo. In this case, you will NOT get any colored offspring, only blues. The male will still produce purple hens.
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So in the case of multiple-expression birds that do NOT include peach, if you breed them together and get blues, then indeed the bird is not the multi-expression bird you thought.
This would work the same regardless of which morph you're testing, so long as it as a sex-linked component and you are breeding it to a component color. Your best bet is to use whichever component color looks the least like the combo-color. For example indigo and purple look similar, so breeding it to a purple might return visually confusing results. But breeding it to a bronze would produce very obvious results. There may be times you don't have much of a choice, if both component colors look similar to the combination of them.
With autosomal-only morphs, it's slightly different. You will either get the mutant color, or you won't. Platinum can look a lot like opal, which is no surprise since platinum contains opal, so if you wanted to test it, you would use bronze. When a platinum bird is bred to bronze, the offspring will all be bronze.
This would work the same regardless of which morph you're testing, so long as it as a sex-linked component and you are breeding it to a component color. Your best bet is to use whichever component color looks the least like the combo-color. For example indigo and purple look similar, so breeding it to a purple might return visually confusing results. But breeding it to a bronze would produce very obvious results. There may be times you don't have much of a choice, if both component colors look similar to the combination of them.
With autosomal-only morphs, it's slightly different. You will either get the mutant color, or you won't. Platinum can look a lot like opal, which is no surprise since platinum contains opal, so if you wanted to test it, you would use bronze. When a platinum bird is bred to bronze, the offspring will all be bronze.
However, when an opal is bred to bronze, you will only get blues.
In this way, despite that platinum and opal LOOK very similar, they will have wildly different outcomes when you test breed. While test breeding isn't really necessary in all situations, it will give you very definitive results rather than guesses.
The caveat is that you do have to know the genetics of the bird you're using to test the bird in question. For example, if you are test breeding a bird you think is platinum, but it carries bronze, or the bronze you're testing with carries opal, you will end up with different results. This is where the "breed 2x the number of total outcomes possible" comes into play.
The caveat is that you do have to know the genetics of the bird you're using to test the bird in question. For example, if you are test breeding a bird you think is platinum, but it carries bronze, or the bronze you're testing with carries opal, you will end up with different results. This is where the "breed 2x the number of total outcomes possible" comes into play.
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In this case, you learn something about your bronze! But, this is where the "breed 2x the number of total outcomes possible" comes into play. If you only breed a couple of birds, you might make the wrong assumptions about your test bird, and you might miss things about the bird you're testing it with.
This kind of test breeding for genes would work with ANY autosomal-only, combination-color, we just don't have any other known autosomal-only morphs as of the end of 2025. This is because it's easier to make a combination with an autosomal + sex-linked, as we know they are not on the same chromosome or in the same locus. I will discuss what happens if they are on the same locus in the "Testing for Alleles" section of this page.
It's also possible - though it hasn't been proven to happen yet with any peafowl combos - that when bred together, some genes may NOT co-express. Which takes us to the next section- gene dominance.
This kind of test breeding for genes would work with ANY autosomal-only, combination-color, we just don't have any other known autosomal-only morphs as of the end of 2025. This is because it's easier to make a combination with an autosomal + sex-linked, as we know they are not on the same chromosome or in the same locus. I will discuss what happens if they are on the same locus in the "Testing for Alleles" section of this page.
It's also possible - though it hasn't been proven to happen yet with any peafowl combos - that when bred together, some genes may NOT co-express. Which takes us to the next section- gene dominance.
Testing for Dominance
As it stands at the time of writing this, we don't have any proven dominant color genes. There is one new color (onyx) being tests in Brazil and appears to be dominant, but further testing is requires to confirm. The leucistic genes (white, pied, and white eye) are all either dominant and incomplete dominant, but they're not colors. They can be considered patterns, and we'll look at that here as well.
What we'll look at first, however, is what happens when one color mutation is recessive to the wild type, BUT is dominant over another mutation in the phenotype. I'll use two colors that haven't been combined- let's use bronze and montana. A multi-gene morph with these two colors together would look like this, genetically: br/br:mo/mo. We don't know what these two genes will actually look in the phenotype when homozygous in the same bird. It could be something that doesn't look like montana or like bronze because it co-expresses, or it could look like montana, or it could look like bronze. If it looks like montana, then montana would be considered a recessive gene, but also dominant over bronze. If it looks like bronze, then it would be considered a recessive gene, but dominant over montana. Being dominant over another mutation does not make the gene itself dominant - that is determined only by the gene's relation to the wild type - but rather it puts it higher on the order of dominance than the other mutation. Having mutations that don't co-express because one is higher in the order of dominance does happen in most other animals, and will likely happen in peafowl at some point. Not every combination will result in a new morph, and knowing which can and cannot combine for new phenotypes is still very valuable information to collect.
The blackshoulder pattern co-expresses with the colors, but since it's a pattern, it isn't considered dominant over the color mutations. This is an example of co-dominance- both the blackshoulder mutation and all of the colors express fully and completely and separately in the phenotype.
However, the blackshoulder pattern and the leucistic mutations can co-express in the phenotype (het white, het pied, het white/pied ("pied"), homo pied ("dark pied")), but where the leucistic genes express, they are dominant over all color and pattern mutations, meaning that they're not co-dominant with those genes. Leucism and other genes also don't affect one another (white over a black shoulder does not make a grey shoulder), which means they don't have incomplete dominance with the known colors/patterns. White, pied, and white eye are dominant over the other colors and patterns, because where leucism expresses, no other color or pattern will express in any capacity.
However again, pied, white, and white-eye do sometimes affect one another, to create silver pied, and white and pied affect one another to create the pied phenotype. This is a case of incomplete dominance in a compound heterozygote- none of the genes express fully, but all of the genes express to some degree, or in ways different than they would in full expression or by themselves, and there's no wild type gene involved.
So all of that to say is that if you are testing for dominance, not all of it is whether the gene is dominant over the wild type. There's an order of dominance you may find yourself having to pay attention to along the way.
Lastly, let's look at testing if a single gene is dominant or recessive... this will get its own page once we have a color or pattern that is a dominant gene, but for now it's here for reference.
If you have a dominant gene, it will not show up in the offspring the way a recessive gene will. The biggest difference is that with a dominant gene, even if you have two birds of the same color, you might still get blues in the offspring- and those offspring WON'T be hets. There's been some rumors that UM "doesn't breed true" (UM x UM doesn't produce 100% UM), and if that's true, there's a good chance it's a dominant gene.
Let's pretend, for this exercise that UM is dominant. This means that UM/UM and WT/UM both look like full UM birds. Let's look at what happens when you breed two of the latter together.
What we'll look at first, however, is what happens when one color mutation is recessive to the wild type, BUT is dominant over another mutation in the phenotype. I'll use two colors that haven't been combined- let's use bronze and montana. A multi-gene morph with these two colors together would look like this, genetically: br/br:mo/mo. We don't know what these two genes will actually look in the phenotype when homozygous in the same bird. It could be something that doesn't look like montana or like bronze because it co-expresses, or it could look like montana, or it could look like bronze. If it looks like montana, then montana would be considered a recessive gene, but also dominant over bronze. If it looks like bronze, then it would be considered a recessive gene, but dominant over montana. Being dominant over another mutation does not make the gene itself dominant - that is determined only by the gene's relation to the wild type - but rather it puts it higher on the order of dominance than the other mutation. Having mutations that don't co-express because one is higher in the order of dominance does happen in most other animals, and will likely happen in peafowl at some point. Not every combination will result in a new morph, and knowing which can and cannot combine for new phenotypes is still very valuable information to collect.
The blackshoulder pattern co-expresses with the colors, but since it's a pattern, it isn't considered dominant over the color mutations. This is an example of co-dominance- both the blackshoulder mutation and all of the colors express fully and completely and separately in the phenotype.
However, the blackshoulder pattern and the leucistic mutations can co-express in the phenotype (het white, het pied, het white/pied ("pied"), homo pied ("dark pied")), but where the leucistic genes express, they are dominant over all color and pattern mutations, meaning that they're not co-dominant with those genes. Leucism and other genes also don't affect one another (white over a black shoulder does not make a grey shoulder), which means they don't have incomplete dominance with the known colors/patterns. White, pied, and white eye are dominant over the other colors and patterns, because where leucism expresses, no other color or pattern will express in any capacity.
However again, pied, white, and white-eye do sometimes affect one another, to create silver pied, and white and pied affect one another to create the pied phenotype. This is a case of incomplete dominance in a compound heterozygote- none of the genes express fully, but all of the genes express to some degree, or in ways different than they would in full expression or by themselves, and there's no wild type gene involved.
So all of that to say is that if you are testing for dominance, not all of it is whether the gene is dominant over the wild type. There's an order of dominance you may find yourself having to pay attention to along the way.
Lastly, let's look at testing if a single gene is dominant or recessive... this will get its own page once we have a color or pattern that is a dominant gene, but for now it's here for reference.
If you have a dominant gene, it will not show up in the offspring the way a recessive gene will. The biggest difference is that with a dominant gene, even if you have two birds of the same color, you might still get blues in the offspring- and those offspring WON'T be hets. There's been some rumors that UM "doesn't breed true" (UM x UM doesn't produce 100% UM), and if that's true, there's a good chance it's a dominant gene.
Let's pretend, for this exercise that UM is dominant. This means that UM/UM and WT/UM both look like full UM birds. Let's look at what happens when you breed two of the latter together.
As you can see in the top left.... Two UM birds produced a genetic wild type, despite that both parents LOOK like Ultramarines.
So how do you make sure you have a homozygous bird, in this case? If there's no DNA test available (and there ARE tests available for some genes in fowl, like you can test for homozygosity in the blue egg gene and the fibro gene for chickens! Unfortunately peafowl have not gotten on the bandwagon yet), then you must use practical breeding to determine this.
If you find you have hets because you get results like the above, then you will want to test-breed the offspring to find the homozygous ones to keep back. Unlike when you're testing for a recessive het, when you're testing for a dominant het, you use the wild type. Breeding a wild type to a dominant het will produce 50% wild type and 50% of the color mutation, like so:
So how do you make sure you have a homozygous bird, in this case? If there's no DNA test available (and there ARE tests available for some genes in fowl, like you can test for homozygosity in the blue egg gene and the fibro gene for chickens! Unfortunately peafowl have not gotten on the bandwagon yet), then you must use practical breeding to determine this.
If you find you have hets because you get results like the above, then you will want to test-breed the offspring to find the homozygous ones to keep back. Unlike when you're testing for a recessive het, when you're testing for a dominant het, you use the wild type. Breeding a wild type to a dominant het will produce 50% wild type and 50% of the color mutation, like so:
However, homozygous dominant mutation will still produce 100% offspring in the mutant color, but all of the offspring would be heterozygous, like so:
Again, this is not a REAL inheritance. So far, we have no proven, single-gene, dominant mutations. Onyx may prove out dominant, maybe UM will, but as of December 2025, I don't have proof of any true dominant colors or patterns, so this is only a made up example for educational purposes.
Testing for Alleles
Alleles are fun (derogatory)! If you've forgotten, alleles are genes that are different from each other, but exist on the same locus, and so replace one another on the chromosome. This means they cannot exist in the same bird at once. Peafowl have two known alleles- white and pied, and US purple and EU violet.
The easiest ways to tell if a gene is an allele to another gene is to test breed them together, and if you don't get any wild types, there's a good chance that your genes are alleles. The caveat here is that this won't necessarily work if the gene isn't novel/unique. If you have a new MORPH but no new MUTATIONS, as in the case of multi-gene morphs, then if you breed that morph to one of its component colors, you would get the component color. This would also occur if one gene is dominant over the other. In some cases, there's enough variance within a color mutation that someone could mistake a variant of a color for a whole new color.
Now, people have bred a LOT of the different colors together over the years, but not all of them. So it's possible that there are current genes that are alleles and we just haven't found them yet. So, let's make up a pretend new gene to use instead, Pearl (pr), and say that it's an allele to Opal. When bred to Opal, this is what it would look like on a gene table:
The easiest ways to tell if a gene is an allele to another gene is to test breed them together, and if you don't get any wild types, there's a good chance that your genes are alleles. The caveat here is that this won't necessarily work if the gene isn't novel/unique. If you have a new MORPH but no new MUTATIONS, as in the case of multi-gene morphs, then if you breed that morph to one of its component colors, you would get the component color. This would also occur if one gene is dominant over the other. In some cases, there's enough variance within a color mutation that someone could mistake a variant of a color for a whole new color.
Now, people have bred a LOT of the different colors together over the years, but not all of them. So it's possible that there are current genes that are alleles and we just haven't found them yet. So, let's make up a pretend new gene to use instead, Pearl (pr), and say that it's an allele to Opal. When bred to Opal, this is what it would look like on a gene table:
As you can see, there's no wild type involved, and there's no colon (:) because both genes are in the same place. We see this happen when white is bred to dark pied! In the case of W/p, what we see is actually a case of partial dominance (white patches instead of turning white like a while, or being blue like a homozygous pied). We also see this when US purple is bred to EU violet, which is how we know they are alleles and not just both sex-linked the way purple and cameo are. Let's look at that comparison!
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This comparison hopefully helps you understand the genetic side of an allele. Unfortunately, there's no way to predict which way the phenotype will look. Maybe there will be a blend of the two colors or patterns, but maybe there will be an order of dominance issue. For example in quail, they have three sex-linked colors that are alleles- roux, brown, and ginger. Brown is recessive to the wild type, but it will show in single copy, even if there's a roux or ginger gene present. When a bird has one copy of roux and one copy of ginger, the bird will look roux, not like a combination of the two. This also means that a bird that looks like one color could be hiding an allele that is recessive to the phenotype color.
The good news is that, as mentioned earlier, we haven't discovered this to be the case for any colors in peafowl. That doesn't mean this isn't the case for any of our colors, just that this hasn't been tested for all color combinations.
There's also a chance that some mutations happen on the same CHROMOSOME, but not in the same LOCUS. This would mean that unless chromosomal crossover happens in a really lucky way, we wouldn't be able to combine those colors into one bird, since the chromosome travels as a (mostly) whole piece. This happens with the sex-linked genes (peach is an incredibly, incredibly rare genetics event that isn't typical at all of how genetics works... we broke genetics with that one). For example, you can't have a peacock that is homozygous purple AND homozygous Sonja's violeta, because the males will just inherit one of each gene because the chromosomes travel as a whole unit. So, FUNCTIONALLY, genes located on the same chromosome (even autosomal ones) may "replace each other" like an allele, but would still produce blues.
Again, this hasn't been proven in any of the mutations we currently have, but also VERY few people keep records or know what they're looking for, and some of the mutations are quite rare these days, so testing opportunities are few and far between.
The good news is that, as mentioned earlier, we haven't discovered this to be the case for any colors in peafowl. That doesn't mean this isn't the case for any of our colors, just that this hasn't been tested for all color combinations.
There's also a chance that some mutations happen on the same CHROMOSOME, but not in the same LOCUS. This would mean that unless chromosomal crossover happens in a really lucky way, we wouldn't be able to combine those colors into one bird, since the chromosome travels as a (mostly) whole piece. This happens with the sex-linked genes (peach is an incredibly, incredibly rare genetics event that isn't typical at all of how genetics works... we broke genetics with that one). For example, you can't have a peacock that is homozygous purple AND homozygous Sonja's violeta, because the males will just inherit one of each gene because the chromosomes travel as a whole unit. So, FUNCTIONALLY, genes located on the same chromosome (even autosomal ones) may "replace each other" like an allele, but would still produce blues.
Again, this hasn't been proven in any of the mutations we currently have, but also VERY few people keep records or know what they're looking for, and some of the mutations are quite rare these days, so testing opportunities are few and far between.
Reverse-engineering Combination Morphs
"What the heck does THAT mean?!" Have you ever looked at a new morph and wondered what genes made it? Especially in the case of new morphs where the breeder won't share the genetic makeup? I have got great news for you! You CAN use practical test breeding to discover what's under that bird's hood.
Since MOST people use sex-linked colors in their new morph agendas, the easiest first-step to take is to breed a male of the new color to a wild type hen. This will immediately tell you if there is a sex-linked component color (there almost certainly will be), and which one it is.
From there, you can either pair the male to multiple hens in different colors (or hens with multiple splits!) and see what colors pop out, or breed the offspring together and see what colors pop up. IF you have access to clean hens in all colors (no hets of other colors), then breeding the male to them will get you easier AND more reliable answers (especially if you have a good guess on which colors are in the mix), but if a male is carrying a single copy of recessive gene that is unrelated to the morph's phenotype, you may get false positives if you try to do more than one hen at a time. For example, if you have a male that's homozygous midnight, homozygous Sonja's Violet, and heterzygous opal, if you breed him to an opal hen, you will get some opals. But, importantly, you won't get ALL opals, which will tell you he's only split, and you can ignore that color. If there are multiple hens, you may not know which hen laid which egg, and could miss the "split" because you assume the non-opals belong to different mom.
Since MOST people use sex-linked colors in their new morph agendas, the easiest first-step to take is to breed a male of the new color to a wild type hen. This will immediately tell you if there is a sex-linked component color (there almost certainly will be), and which one it is.
From there, you can either pair the male to multiple hens in different colors (or hens with multiple splits!) and see what colors pop out, or breed the offspring together and see what colors pop up. IF you have access to clean hens in all colors (no hets of other colors), then breeding the male to them will get you easier AND more reliable answers (especially if you have a good guess on which colors are in the mix), but if a male is carrying a single copy of recessive gene that is unrelated to the morph's phenotype, you may get false positives if you try to do more than one hen at a time. For example, if you have a male that's homozygous midnight, homozygous Sonja's Violet, and heterzygous opal, if you breed him to an opal hen, you will get some opals. But, importantly, you won't get ALL opals, which will tell you he's only split, and you can ignore that color. If there are multiple hens, you may not know which hen laid which egg, and could miss the "split" because you assume the non-opals belong to different mom.
You also won't be able to use the offspring of colored hens to learn anything more, which is why breeding a male to a known, clean wild type and then breeding those offspring together may be faster in the long run. However, it also bears the possibility of false positives, because the offspring may both carry the het gene, and create an unrelated color. In this case, there's not a good way to tell if the color is related or not, just that the male carries. So you would want to breed the offspring to one another, look at THEIR offspring, and use those colors to test the male with individual hens. This will not save you time, but it will save you money- you will have all the colors on hand (from the grandchildren) to breed back to the OG male. At that point it's a simple matter of testing for splits/proving genetics.
If you have other questions about testing genetics that weren't answered here or on the other pages, please feel free to come ask me in a live chat on my farm's discord!
If you have other questions about testing genetics that weren't answered here or on the other pages, please feel free to come ask me in a live chat on my farm's discord!