Even though it doesnt happen to everyone it doesnt mean that it doesnt happen! It has happened to me quite a few times so it doesnt really bother me anymore, but at the time my birds were not practicing. My chickens get a diet of layers pellets, wheat, grit and oyster shell as well as the occasional green stuff from home, and it still happens occasionaly so there could be truth in what I was told, but then again if you guys/gals dont get things like that happening to yous and have kept chickens for a while then I cannot explain it, I would of thought that only the young birds would be practicing, I got some off ex battery hens, which had all been laying for ages, so I do not know exactly. But I'm going to do some research on what I was told and I'll get back to you all. I have only kept hens for just over 1 year now so theres still alot I need to learn about them but this also happens to other peoples hens near my allotment.....It's wierd!!! Ive never had any really young birds so cannot say for sure but if you think about it it does make sense what the old guy told me, all females have a cycle, no matter what she is, woman, horse, chicken, frog and their cycle is governed by the moon, the same as the tides..... Women create eggs once a month when they are ovulating, chickens are different, they can produce eggs everyday and this is because they are all produced at the same time on this so called bead, but they are all so small, and enable the sperm from the cockerel to enter each one, why do you think your hens produce fertile eggs for up to 1 month after being with a cockerel? They grow as they are due and the ones at the end are these little ones, because sometimes the bird produces too many eggs at the start of each of their months, the difference between the days of the month probably does this to them, as some months are 30 days some are 31 as you all know, and sometimes, not every time and not every bird produces more than it should, some birds can lay twice a day, its all in their breeding I think. But like I said I will try to find out more about their cycle...