Crests, different types of combs, different colors, feathered legs, and a host of other traits: They all arrived on the planet via mutation at some point in time. So yes, I agree this had to be a mutation. I don\'t think there were any crested birds in the background of the silvers were there John? Jerry, remember years ago when you hatched some silkied silvers?
That one might have been a recessive gene lurking in the line until the right two birds were mated up, but who knows?