You should try to find some list of color names and their associated genotypes specific to Australia because common usage names for colors vary a little bit by the country. I wonder if someone from one of the waterfowl clubs there has something they can pass along? I would love to see it if you end up finding someone that has something like that.
As far as the color and based on what you have said in PM's, she is either not entirely correct about the parentage or it is another case of colors being named differently there. It is not possible for a hen to be "split Buff" (I think that is what you said in PM). It is a sex-linked recessive, so the hen would be visual Buff. Also, it is doubtful she was lavender (unless again, what you guys call lavender is a different genotype). Here in the states, lavender in the Mallard breeds is homozygous extended black (E/E), homozygous blue (Bl/Bl), and sex-linked brown dilution (d/d).
Everything else though, if I am recalling correctly what you said via PM, seems reasonable. The father may have very well been Pastel (heterozygous or "split" for light phase or harlequin phase), and buff. The hen must have carried blue as well, because the bird is such a light blue grey, he almost certainly is homozygous blue plus whatever else is going on (whether restricted Mallard, light phase, buff, etc..). The problem is that once you get a bird so light in color, there can be any number of genetic possibilities that give almost identical appearances. Based on the lack of claret, it is very possible that he is something like Saxony (light phase homozygous Blue) with the addition of sex-linked Buff. That is something that Holderread has called a form of "pseudo-Saxony". Outside of doing test crosses with the bird, there is little way to know for sure what he is. He is the perfect example of why it is so valuable to keep Mallards in your collection. You could breed him to a Mallard hen and pretty easily narrow down what he is genetically. For example, if bred to a Mallard hen-
1. If he is homozygous blue as I suspect, all offspring will be Blue Fawn (unless he also is carrying Buff).
2. If he is carrying restricted Mallard, all offspring should show that as well.
3. If he is carrying Buff dilution, all female offspring should also have Buff (might be hard to discern, depending on how many other genes end up being involved, but at a minimum, the hens should look different from the drakes).
4. You wouldn't be able to tell in the F1 generation if he is also light phase or harlequin phase, but you could likely do so if you bred the offspring together to the F2 generation.
Anyway, HTH. It might be a fun project figuring out what color he is if you have the room to do it!
