National Geographic had a short bit on starling murmurations, with pix by Søren Solkær, last fall. In the pic above, a falcon is in the groove on the right. The article discussed some reasons for how murmurations form. It is not all predator avoidance and mysteries remain.
I am not sure if passenger pigeons performed murmurations but if they did their size and numbers would be an incredible sight.
There is still talk of de-extinction of passenger pigeons but the article in the link says big snags have been found with de-extinction in general.
The above is hype but if they can get it to work it would be interesting.