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UPDATE 31/12/2018: after severall testmating (from differend breeders) we were able to confirm that in Agapornis fischeri there is also a blue type 2. Homozygote birds blue type 2 are completely blue, without any psittacine traces, but in combination with normal blue (type1), the birds (bl1/bl2) have a turquoise phenotype.
You can read all about it here: https://www.ogvzw.org/?p=15088
Blue, aqua and turquoise mutations in Lovebirds
Published in BVA Magazine 2014
By Dirk Van den Abeele
MUTAVI, Research & Advice group
Ornitho-Genetics VZW
Translated by Daniel Nuyten
Blue.
The first blue colour mutation in parakeets most likely appeared in budgerigars. Reports of blue budgies already date back to 1878 when one was born by a breeder in Belgium. (van der Linden, 2002, p.9).
However, this wasn’t the only species where blue birds showed up. During the years blue mutations appeared in many species. In lovebirds they found the first blue Agapornis personatus in a shipment of imported birds from Tanganyika (Tanzania) to England in 1927 (SETH-SMITH, 1932). Blue A. fischeri, A. nigrigenis and A. lilianae were acquired through transmutations. There are also *blue* Agapornis roseicollis, but everyone knows by now that this is a selection type of turquoise, so genetically not a true blue mutation.
I can imagine that these new appearances strengthened the enthusiasm of many breeders and provided many new mutation combinations and new challenges. The normal green colour of these species suddenly became blue and where we had red or yellow feathers we got white ones instead. A wonder had happened for sure.
Blue mutation in feathers of the structural type.
We now know that green feathers in lovebirds get their blue colour due to the disappearance of the normally present yellow psittacin. In other words, the blue feather colour that we see in parakeet species has nothing to do with the presence of blue pigments. Instead, it is caused by the structure of the feather. In a green feather of the normal wildtype, the eumelanin present in the medulla (the middle of the feather) absorbs the light. In the part of the feather that we call the spongy zone, blue light is formed through interference (J. Dyck, 1971; Jan Dyck, 1971). That blue light is sent back out through the cortex (the outside part of a feather). In the cortex there is a yellow pigment called psittacin. The combination of the blue light and the yellow pigment causes the green colour.
To get a blue bird in lovebirds we need a feather of the structural type and a mutation that blocks the yellow psittacin pigment completely. We still have the blue light, which was formed in the spongy zone, but the yellow filter is missing. Result: we only see the blue light.
This makes the blue a structural colour and feathers that have this typical structure are called feathers of the structural type (logical isn’t it?).
Inheritance of the blue mutation.
The inheritance of blue is quite simple. This mutation inherits autosomal recessive compared to the wildtype. I will give you some combinations:
If we pair a pure green bird with a blue one (In this instance it does not matter if it is the male or female which is green or blue), we get all green young, but they are all split blue. So in this pairing all young are phenotypical green, but genotypically they are heterozygote for blue or green split for blue. Of course you can’t see from the outside whether these birds are split or not. In articles we mention this as: green/blue.
When we then pair a green bird split blue with a pure green one we get:
50% chance of green
50% chance of green/blue
This combination is of course not recommended. All young birds are green and only test pairings can show us which birds have the blue factor and which don’t.
We get the same problem we get when we combine two split birds (green/blue x green/blue).
Then we get:
25% chance of green
50% chance of green/blue
25% chance of blue
With this combination there is a 25% chance of pure green and a 50% chance of green split for blue. Also here the green birds will not show any signs that they are split blue. These birds are called in breeders jargon “chance split”.
A better combination is to pair a green split blue (green/blue) x blue. Here we have a 50% chance of green/blue and a 50% chance of blue young. This is a combination that gives clearer results than the previous ones. With these young you are certain that all green young are split blue, the other ones are normal blue.
The easiest is of course to actually pair blue with blue, as all young are then of course blue!
We can’t conclude that in lovebirds the blue mutation results in weaker young.
Strictly technically speaking, the blue mutation is the result of the complete absence of the psittacin in normally green feathers. In other words, blue is a mutation of the CPR type (Complete Psittacin Reduction).
PPR – Partial Psittacine Reduction.
So you would think blue is very simple, until we look further into it. We then notice that in the range of “blue” birds the colour can vary a lot. This is because over time we have also got mutations that do not give us a pure blue colour, instead a colour that is more between green and blue. This colour has been called “appleblueseagreen” or in the worst case it was mistaken for a true blue.
For most breeders these PPR mutations (short for Partital Psittacin Reduction) are difficult to understand and these forms were often seen as to be developed blue colours. Now we know what we are dealing with and we realise that we are working with true mutations. Like eumelanin mutations where we have several reduction forms, we have the same in psittacin mutations and so these are PPR mutations. So we see colours that are intermediates between green and blue. The normally red, orange or yellow feather fields will appear paler in colour from the psittacin reduction. They can vary from almost white (most of the time described as crème/cream by breeders) to pink.
Until now we recognise and have proven two different PPR mutations in lovebirds. These are aqua and turquoise.
Aqua.
This first aqua mutation in lovebirds appeared in the early 60s in The Netherlands, in A. roseicollis.
With this mutation we see an equal reduction of the present psittacin. The reduction is around 50%. This results in birds that are neither green nor blue, but a colour somewhere in between. The feather fields that are coloured red become light pink and the yellow feather fields become lighter yellow. In the past several terms were used to indicate this mutation, the most common ones were seagreen, seablue, ivory, pastel and pastel blue. When people tried to provide a more uniform naming this mutation got the international name “aqua”, which is short for aquamarine. In other lovebird species we don’t see this mutation yet, in A. fischeri we have aqua phenotypes on a regular basis, but until now all of these were modifications.
Turquoise.
Contrary to aqua, turquoise gives a more variable reduction of the psittacin in the feathers. We find the turquoise mutation in A. roseicollis since the 70s, in A. fischeri and A. personatus they showed up only a few years ago. In lovebirds the turquoise mutation gives a reduction of around 90% on the body, whilst the reduction on the wing coverts is limited to +/- 65%. This results in a bird with an almost blue body and green deposits mainly the wings. In A. roseicollis the mask is more crème coloured, in A. fischeri it is yellow instead of the orange-red we see in the wildtype birds. That is why some breeders call it “yellow face” instead of turquoise. We can conclude that this mutation in A. fischeri is as good as identical to the turquoise mutation in A. roseicollis. The difference in mask colour in both of these species is simply explained by the fact that we have different mask colours in the wildtype birds, and so a different psittacin combination.
In A. personatus we have a blue bird with green deposits in the feathers and a light yellow chest colour. Here people tend to speak about parblue instead of yellow face. Either way we are dealing with a variable psittacin reduction which causes this phenotype, in other words this is also the turquoise mutation. Anyway, why would we give them all these different names when they all tick the boxes of the turquoise mutation?
A striking and interesting fact here is that the red deposits on the chest and the red psittacin in the black head feathers of the turquoise A. personatus are almost completely gone. I will address this further in a future article.
Aqua and turquoise are sometimes called parblue mutations (partial blue). A term that isn’t bad, but personally I prefer the term PPR (partial psittacine reduction) as this term can also be used for parakeet species that have no feathers of the structural type like for example the cockatiel. In cockatiels there are also psittacin mutations, only these don’t result in a blue colour because feathers of the structural type are missing.
Both aqua as turquoise inherit autosomal recessive against the wildtype.
Some breeding results for aqua:
aqua x green: (or green x aqua)
100% green/aqua
green/aqua x aqua:
50% chance of green/aqua
50% chance of aqua
green/aqua x green/aqua:
25% chance of green
50% chance of green/aqua
25% chance of aqua
Turquoise gives identical results:
turquoise x green:
100% green/turquoise
green/turquoise x turquoise:
50% chance of green/turquoise
50% chance of turquoise
green/turquoise x green/turquoise:
25% chance of green
50% chance of green/turquoise
25% chance of turquoise
So far nothing special, but things get a bit more complicated when we pair aqua with turquoise or with blue. Then we see an intermediate colour appearing. This proves immediately that aqua, turquoise and blue are genetically alleles of each other. In other words they are all mutations of the same bl-locus or variations of the gene that is responsible for the pure blue mutation as well.
The phenomenon of alleles or multiple allelomorphs is not always understood well by breeders and that’s why I would like to try to make this a little clearer. This time I will not explain through theory, but with proven examples.
-We know that if we pair two identical autosomal recessive mutations together, i.e. blue x blue, we get young that are all blue. So autosomal recessive mutation x identical recessive mutation gives mutation.
– If we pair a blue bird with a pure green wildtype we get all green wild form young, but these young are split blue.
-The same when we pair two different autosomal recessive mutations. A good example is when we pair a (pure) blue with a (pure) NSL ino, all young are again green but split for both mutations.
In other words, we see again and again that when we combine a recessive mutation x wildtype, or when we combine two different recessive mutations that the wild form always comes back in the offspring. This shows that these mutations are recessive or submissive to the wildtype.
This clearly changes when the autosomal recessive mutations involved are alleles of each other. If we pair for example; aqua with turquoise, then we don’t get green wild form birds split for aqua and turquoise, (which would normally be the case when we combine two different autosomal recessive mutations), but we do get a typical intermediate colour. This intermediate colour, when combining two recessive mutations, proves that both mutations are alleles of each other.
In the past people thought that this was a different colour and so a different name was given for these phenotypes. A typical example we find in A. roseicollis, where the combination of aqua and turquoise was called ‘apple green or seagreen’. It later became clear that this was far from ideal and many breeders thought they were dealing with a separate mutation, which of course couldn’t be further from the truth. When we paired these ‘apple green or seagreen’ A. roseicollis with green we got some young only split for aqua and some young only split for turquoise. There is never a split for ‘apple green or seagreen’.
To avoid this kind of confusion we now apply international agreements. These indicate that for a phenotype (colour) that is caused by the combination of two alleles of the same gene we do not use a separate name. We will describe this colour combination simply by writing the present mutated alleles together in one name. So the combination of aqua and turquoise is called AquaTurquoise. To avoid that this is seen as a single mutation and to emphasise further that two different alleles are involved in the phenotype, the first letters of both alleles are written with a capital letter. So we see with AquaTurquoise immediately that we are dealing with a combination of aqua and turquoise. The agreement also states that the least mutated mutation (the colour closest to the wild form) is placed first. So aqua is reduced 50%, turquoise is usually reduced more, so aqua is written first.
If we pair AquaTurquoise with AquaTurquoise then we get:
25% chance of aqua
50% chance of AquaTurquoise
25% chance of turquoise
Still we get breeders regularly claiming that they bred ‘apple green or sea green’ from two green A. roseicollis, and their logical conclusion is that it has to be a separate mutation. Unfortunatly the logical mind is often wrong. Here we are dealing with two green birds that are split; one for aqua and the other one for turquoise.
If we combine: green/aqua x green/turquoise:
25% chance of green
25% chance of green/turquoise,
25% chance of green/aqua
25% chance of AquaTurquoise.
Another combination that often surprises us is green/aqua x turquoise:
50% chance of green/turquoise
50% chance of AquaTurquoise.
It becomes even more complicated within a species where we can find blue, turquoise and aqua. This often causes typical jargon. A clear example of this we can find, among others, in ring-necked parakeets.
Thirty years ago, next to the blue ring-neck we also got a turquoise mutation. Breeders concluded as well that with the combination of turquoise and blue, they again got turquoise looking young. This made many conclude that turquoise is dominant over blue. When turquoise and blue were combined, rather than calling the resulting offspring TurquoiseBlue, most of time it was called SF or single factor turquoise. When a bird was homozygote or pure turquoise they called it DF or double factor turquoise.
This was a logical explanation, but scientifically not correct as we can only speak of a dominant inheritance when a mutation is dominant over the wild form. Another big misunderstanding that was caused by this wrong interpretation was the idea that you always had to pair a turquoise to a blue bird, or else and I quote a breeder: “You will lose the mutation”. From reading the previous part of this article we can conclude that we actually know better now. Like blue, turquoise and aqua are autosomal recessive mutations. This means that combining these alleles with green gives normal green split birds.
I will now give some examples based on turquoise and blue. The results of aqua and blue are identical, you only have to replace turquoise with aqua.
Blue x turquoise gives 100% TurquoiseBleu (TurquoiseBleu looks like a turquoise). Also, the correct use of capital letters is important here, as the breeder can see clearly that this phenotype is the result of combining two alleles; blue and turquoise.
Several other combinations:
TurquoiseBlue x TurquoiseBlue:
25% chance of blue
50% chance of TurquoiseBlue
25% chance of turquoise
In species where we can find blue, aqua and turquoise, various combinations are possible.
I will put them down for you.
blue (homozygote)
turquoise (homozygote)
aqua (homozygote)
TurquoiseBlue
AquaBlue
AquaTurquoise
One of the current problems is how to recognise the colour difference between turquoise and TurquoiseBlue in A. fischeri and A. personatus. I suspect that the colour of the beak could give us an answer, but I don’t have sufficient evidence of this yet. Good administration and record keeping when breeding with these mutations will soon give us an answer.
Are other alleles of the bl-locus possible?
A logical question is whether or not other alleles of the the bl-locus are possible, along with aqua and turquoise. Of course, this is possible. The only problem is how to accurately establish that a new allele has mutated. As you can establish from this article, PPR mutations and their combinations can give a highly variable appearance. (Also if you take into account that in budgerigars a second locus is known that causes psittacin reduction, you understand that this isn’t very easy at all.)
Still there are breeders that swear that their PPR or parblue birds are different from normal aqua or turquoise. It is worth noting that apart from psittacin reductions, many other factors can influence the colour of blue or PPR mutations.
I will put them down for you:
Structural changes of the feather:
– The width of the spongy zone (which is related to the dark factor as well)
– The nanostructure of the keratin in the spongy zone (also responsible for the violet factor)
Chemical changes:
– The amount of psittacin still present in the feather
– The chemical composition of the present psittacin
– The chemical composition of the keratin which form the composition of the feather
Genetic causes that influence the colour:
– Sex of the bird (hormonal workings)
– Combinations with other PPR alleles
– Combinations with other mutations like slaty, misty, violet etc.
– Anticipation of the turquoise locus (a good example can be found in Agapornis roseicollis, where we see that through selection most birds appear almost completely blue)
– Crossing-overs could combine different factors and give us the false impression that we are dealing with a separate mutation.
– Pleiotropy (influence of multiple genes on the phenotype), modifying genes (combinations of genes that reinforce or weaken certain effects), translocations etc. All these processes could change a colour without being a new mutation.
Other external causes could be: light, condition etc.
Normal feather research can’t give a conclusive answer on this, and so it is of the greatest importance that when we suspect the establishment of new alleles we make targeted test pairings. A first step is to combine these mutations with pure wildtype birds, to exclude the presents of other alleles and ensuring that we start with homozygote birds. This will take quite some time, but it is the only way to get correct results. Remember either way that “a different coloured phenotype” is not always a mutation … just my thoughts.
Literature
Dyck, J. (1971). Structure and spectral reflectance of green and blue feathers of the Rose-faced Lovebird (Agapornis roseicollis). Munksgaard.
Dyck, Jan. (1971). Structure and colour-production of the blue barbs of Agapornis roseicollis and Cotinga maynana. Cell and Tissue Research, 115(1), 17-29. doi:10.1007/BF00330211
van der Linden, H. (2002). Grasparkieten. Van Spijk.
McGraw, K. J., & Nogare, M. C. (2004). Carotenoid pigments and the selectivity of psittacofulvin-based coloration systems in parrots. Comparative Biochemistry and Physiology, Part B, 138(3), 229-233.
McGraw, Kevin J, & Nogare, Mary C. (2005). Distribution of unique red feather pigments in parrots. Biology Letters, 1(1), 38–43. doi:10.1098/rsbl.2004.0269
SETH-SMITH, D. (1932). Mutant of A.personata. Proceedings of the Zoological Society of London, 1418.
Stradi, R., Pini, E., & Celentano, G. (2001). The chemical structure of the pigments in Ara macao plumage. Comparative Biochemistry and Physiology, Part B, 130(1), 57-63.
