free acrobatic show

as i was driving home this evening ...close to sunset...i saw a swarm of birds performing acrobatics. group acrobtics. the snow geese are flying overhead now in their typical raggedy v shapes, but i am pretty sure the swarm was not snow geese. they were tightly packed and performed as one, it seemed as if they had one mind or were connected like the borg. the maintain a tight group that folded over and over on itself making them appear like a black cloud one minute and nearly invisable the next. sometimes they were in an oval shape and sometimes they stretched out into a pencil shape. i had my camera but they were to far away. they would have been like pencil dots.