Trying to create this dynamic effect has been a bit of a battle! And a repeated glitch of crows flying sideways instead of away from the central particle emitter. Though the fifth still image would have you believe I had crows flying in a beautiful circle. They were not.
Having battled a while I got some help and discovered I had confused Maya and with a little prodding got it working. I am really very pleased with how well these Crows work. I have a few playblasts of how I'd like them to be used and the sorts of camera angles I might need. I even managed to import them into the Hills of the Dead scene for which they were also intended!
Referring back to my storyboard for aid I am going to try and work out what kinds of angles I'd like my crows to fly and perhaps create a small stock folder of Crow transition renders ready for compositing in After Effects in Post Production.