‘Oh, look at the birds,’ I heard from the window office behind me. I wandered into my boss’s office to see a sea of redwing blackbirds all over the fields and trees behind our building.

I went out the door in the cafeteria, and they all leapt into the air.

Yes, each and every black mark in this photos are birds, creating tiny cuneiforms in the overcast sky. Their red patches kept flashing here and there as they banked.
(each photo is a link to a 640×480 view of the same pic, so you can see a bit more detail. )

Moments before I startled them, they had been gliding and landing in the field and trees, hoping up and down in the short grass, the height of it enough to hide them.

A bit creepy in general… though the adults around mentioned the movie ‘The Birds’ more than once.