Crows Playing Swinging from a Branch

These are wild crows playing in our back yard north of Boston, MA, USA, swinging upside down on a willow branch and knocking each other off. I believe these are a group of young fish crows who have been playing this game a few times a week for the last couple of weeks, always using the same branch. There seems to be a marked difference in skill, with one crow appearing much better at it, although the others seem pretty enthusiastic anyway.