Yes the population is moving Ulco.
Just guessing but with the current limitations a single moving object would be hard to animate over the ground (pivot point moving).
But for flying objects or water it could be desirable even.
Hannes, i mean for a test just one object (one bird) sequence would be enough (for a test).
More birds would be nice but for a flocking sequence 3-5 birds could be enough.
And i think it is not so hard as it looks.
Use one bird (you should have it already...just delete the others).
Animate it 10-20 frames. So much you want.
Then when you have say "bird_001.obj" to bird "bird_010.obj" for example just copy them and rename the order with batch file renaming.Copy and batch offset the names so much you want.
You could have easily 10-20 etc. offset bird sequences in this way just in minutes.
Edit: You could use just images too maybe on card or plane objects.Your bird object sequence wouldn't be so big in this case even.
If you want you can make same videos of course