To keep pedigree of EVERY chick, I use food color on hatchlings, on their striping, head, under wings (lasts the longest). Make a code, one stripe, both stripes, different color on stripes. Red and Blue last the longest before reapplying, especially, if under hens (then under their wings on the skin lasts very well). THEN you will know the bird's pedigree when old enough to ring and RECORD each bird! I use numbered bands, one color for each year, so at a glance in the pasture, you know the year your hen/cock hatched! Put them on as soon as they will stay on and will not slip above the hock joint (to hide--and you think the bird lost his band.) Sealed bands go on as soon as you can bunch the toes and slip it on--stays for life-- Size 5 for females, 6 for males, sorry we in the US have never been properly taught metric--are stuck with inches, feet, yards, ounces, pounds. So for pullets, 5/16", cockerels, 3/8". Just be sure to "do it"!