We have some local crows at our slope that stop by for a snack every once and a while. If they see you rolling along the lip of the slope they'll fly by and try it, but they seem afraid to roll all the way over, so they half-roll to inverted, pause, and roll back. You'll usually hear a little "haa" as they do it.

Turkey Vultures are another story. The see us flying combat and they get sort of, agitated, for the lack of a better word, and want to fly in the same air we're flying in. My friend Joe and I were flying at the coast in Marin once and standing about 20' apart and a Turkey Vuture swooped in out of nowhere and flew right between us at shoulder level.