Thanks for sharing your precious experience to us KenM,
I'm not sure if I got what you exactly meant, but I can expalin the field situation, it might be helpful.
There were about hundreds of Coots feeding on the water of wetland, as we noticed a group of Ducks who were feeding near them, started flying suddenly cause of the presence of a Western Marsh Harrier flying above them looking for it's breakfast.
The flocks of Coots didn't start to fly and kept feeding on water, but the ones who were feeding between Duck's group, were feared and started flying with Ducks.
And as Joern mentioned above, in migration season, I saw them flying over Caspian sea in day light, but rarely, so maybe you are right.