Gibbers
So the thing to remember about the gibbers is they travel from tree to tree up high, on the ground and carry the news. Someone who has the ability to send a message through the gibbers could send it all across a continent if someone on the other end could also get a message from the gibbers, but that is what Heron is talking about when he speaks of sending a message through the woods, either the gibbers or the planet’s energy lines.