i have a male and a female both of the ceres are blue 1 dark and 1 light. my male is older than my female, the dark blue ceres on a male sometimes mean they are in breeding mode sometimes it's just the color of the cere and the brown ceres with a little bit of tan mean the females might be in breeding mode if ur keets are old then they could just have crusty ceres but if there about a year old then they could be in breeding mode, maybe not. i got that from LLPB the only way to really be sure is to ask ur vet. u can't tell by the color of there ceres really though birds can have all different color ceres, and that more stripes they have on there head the younger they are thing is off because i got mine a month old and they didnet have any stripes on there head. the best advice i can give is just look at ur parakeets to see if u find anything abnormal. if u do then call ur vet.
