The bats have been sent on a Mission. It's a very important Mission, and something that will be of great help to their Boy.
They swarm through the night, canvassing the fields, until one of them finds the flat wood outside the large hole. He releases an ultrasonic chirp, and the others converge on his position.
They'll have to go about this carefully — they don't have their normal preparations to rely on.
A lead bat dips her head into the hole and squeaks, to hear what's inside.