Male great tits respond to the calls of other males by calling back rapidly, and thus overlapping the incoming call with their own.

ECONOMIST: Parasitology: The song does not remain the same | The

As a result, a scene with back-and-forth dialogue in the play might now have what Mr. Shanley describes as "overlapping dialogue, " a braided conversation that becomes a musical duet.

WSJ: A Re-'Doubt'-able Effort | John Patrick Shanley | Cultural Conversation by Judith H. Dobrzynski