I have been wanting to gather up a series of flying bird shots for quite awhile so I could use them in composite images, just like this one. The other day I had my chance. A large flock had landed on the phone wires above the street. I slowly positioned myself beneath them with my Fuji X-Pro2 and 18-135mm lens. Once I set the lens to over expose to compensate for the bright sky, I clapped my hands a couple times and the entire flock took off making a couple of circles above me. Plenty of time for me to grab a bunch of shots for future use.
Today I decided to make one image with some bird shots and put together this composite with a model I had photographed on white in the studio. All in all I used three separate bird photos, one sky, and the shot of the model with I duplicate, softened with a 30% gaussian blur, changed its Photoshop layer mode to "Overlay", and put it over the normal image of the model. This gave me a very soft, contrasty photo of the woman.
The sky image was in "Multiply" mode and the top layer. The bird layers were on the bottom with their layer modes changed to "Darken" to wipe out the sky and silhouette the dark birds. That was pretty much it.