This color variety, seen at its best on Anconas, has progressive more, and larger, white spots with each successive moult. Most Anconas have the correct amount of white in their first adult year and are too white in future years. Some birds have too few white spots first time round. Expert exhibitors know that if a few carefully selected body feathers are removed as soon as they have grown their first adult feathers, the replacement feathers should come out with proper white spots. So a fresh show team must be bred annually . Above is my mottled rooster Oreo who was born with too much white.
This is my Mottled hen in 2012 who in this photo has good pattern for her first year.
This is the same hen from above who this year has an over all too white appearance which is considered a disqualification in the breed.
Above is Oreo. Only Anconas can be relied upon to produce a whole batch of uniformly spotted youngsters . Other breeds with this pattern like Belgian d'uccles ,are usually very variable. Breeders of Black Mottled d'uccles , Japanese or Wyandottes will be lucky if they breed a uniform showable trio. This is why I have decided not breed black Mottleds for exhibition , but black Mottleds are still as good as any color when it comes to other quality's besides exibition. Info is from Exhibition Poultry Keeping by David Scrivener.