I’m pretty sure I have a couple videos of some of my chickens doing it… putting stuff on their backs while laying, or even while walking around!I've seen hens do it, Fan, Ruffles and a couple of others. I have no idea why.
It's a bit like the going off feed when moulting. Some chickens do, and from the poll, and my own experience; enough chickens do it to make it possibly common to all chickens in similar circumstances.
It would be a long study to give any usefull results.