Oops, I had given up looking by the time you replied. Thanks so much for this. I no longer have the bird, but a friend now has one which does this, so we will try it.
One of my chickens stretches its head in the air then bends its neck right backwards until its head touches its back. Between us, we have seen it do this four times, all on the same morning. It is about 3 months old, and looks healthy in other ways. What could this be?
My brother had a rooster...