Free: Contests & Raffles.
They turn sideways to quickly lose altitude. When the wings are not level they lose lift. I have seen birds do this to drop more quickly into the dekes but am not sure why they would do that while just flying along. It is pretty cool watching them do that though.
coolest part about all of this is to see the still pictures of it... the goose's head never changes plane, the goose still looks straight ahead level eyed while the body rotates around the neck basically the wings fill up and let the air push em down and drop altitude at crazy rates