how do I know ,you should aske the breeder .
if you have BC chicks than his rooster is pure silver cuckoo maybe dark cuckoo ,first cross .I m not really keen on this mixture . unknown origin .
if you really want to work with these chicks you should ask your breeder all this question ,where did he get his rooster from etc............................. more question asked better for the future work .
creating strain of chooks take time /space /lot feed etc...........................
chooks man
he has 2 pens, one bc marans only and another mixed, silver cuckoo roo and bc hens. I wonder if I'll be able to recognize pure bc chicks or there will be mixed colours but looking like pure bc. according to what he says his cuckoo marans are pure. he gave me 2 pure silver cuckoo cockerels but 1 looks like blue cuckoo pullet. time will tell.