I'll steer clear of the controversy about abandoning a landing at 200ft in a bird flock encounter and let the writers of company SOPs sort that out after reading PPRune
I see yet another controversy about bird behavior going up or down.
Having studied the buggers a little I provide the following emperical comments:
It makes a difference how much altitude the birds start from.
on the ground when they see a threat they go up in order to gain manuevering space.
In the air they go sideways in a peeling action and thus fall away both vertically and horrizontally.
Big birds behave in a flock fashion to avoid each other as a higher priority than any other threat
Starlings behave in ball flocks like little bait fishes in the sea. I suppose that there is a nice mathmatical model that predicts this.
I don't suggest that pilots should try to out fox the bird's behavior