The sentence is:
For just at that moment the light came over the hill, and there was a mighty twitter in the branches.
There are 2 different meanings for 'twitter':
- (of a bird) give a call consisting of repeated light tremulous sounds.
- to tremble with agitation
Please, help me figure out the right one. It's from "The Hobbit", when thanks to Gandalf's meddling the 2 Trolls turned to stone at the dawn.