Get the smoke asset pack for free: https://calzaath.gumroad.com/l/smoke (USE CODE "SMOKE")
These are some of my best tips for creating a simulation to fake a flock of birds taking off. Real birds are hard to train to do exactly what you want, so making a flock of CG birds is probably your best bet.
Check out my brother Joe's music here: / @cloudnine3626
Camera tracking tips: 00:05
Reconstruction tips: 00:31
Objects as masks: 00:45
Creating the birds: 00:58
Wing flap animation: 01:12
Particle systems: 01:51
Compositing tips: 02:05
Result: 02:36