I used Peder Norrby's Starlings Study project file as a basis for this effect. I rigged and animated a flap cycle of a bird that I made in Cinema 4D. I then rendered three different angles of the flap cycle. Front, side, and one in-between. Then I used those flap cycle renders as sprites for Trapcode Particular 2. I layered three Particular layers one cycle for each layer. I also used Trapcode Horizon. Sadly, I got some strange compression artifacts.
Trapcode Particular never ceases to amaze me. So many uses. Thank you Peder for developing the best plugin for After Effects!
You can see one of the flap cycles here on my site.