perhaps he picked up a modifying gene or enhancer/inhibitor along the way...The Birds Tim has discussed and the Birds I have originated from the same two that started this whole color, I was fortunate enough to gain access to a few of the first offspring from the initial mating when it was determined they would breed true to color if mated to each other. We just followed slightly different paths with the birds from that point.
hey sinse you are doing the phoenix long tail project, did you use silver duckwing or black breasted red birds? I as this because they are just wild type and if you cross the F1 together you should be able to get a few Opal on a wildtype background chicks. keep an eye for them ok and let me know how they matured