The colour of the birds is sex-linked, so if a black or red rooster is crossed with a Koekoek hen, the produced females will be completely black in colour, while the males will have a white spot on the head.
Mmala wa dinonyana o kopantswa le bonna kapa bosadi, kahoo haeba mokoko o motsho kapa o mokgubedu o tshela le kgoho ya mosadi ya Koekoek, tse hlahisqang ke tse tshehadi e tla ba tse ntsho ka ho feletseng, ha banna ba tla ba le sephahla se se sweu hloohong.