Even young downies will do this, male or female. By lightly patting/pressing on top of the chick's back between the wings with your flat palm you will illicit this response. They will ball up there feet and gradually lay flat and hold still. The hand may imitate mom laying down on them to brood them. As they get older the response becomes more of a tipping bow with the tail moved to the side. It is not a balance thing at all. All of my imprints have done this whether male or female.