There are always changes in colour when a bird matures or moults. Most shades will brighten after the first moult. The 3 yellow face mutations show the most obvious changes because the yellow spreads as well as brightens after each moult.
The stripe across the belly is unusual
Violet is another shade that can look quite different each year on the same bird
Thanks for the advice Nev,
Just wondering...is there any resemblance between the dad's "green-spot" on a "yellow-bird" and these "random-spotted" occurence in the cock bird featured here....or is it difficult to tell?
The dad (shown below), also has an "interesting random-spot" of colour...but I'm still not sure what genetics he carries...spangle for sure, maybe violet (as some babies showed it)....
What do you think about the dad, and the "stripe- / random-spot" patterns?