Before I was ready to go, I was thrown out.

And I mean this literally.
The opportunity came to the Chatterer one day when I was alone in the nest.

My mother and the Chatterer had gone away together toward the blueberry swamp.

He must have planned the whole thing, for I heard him returning alone through the forest, roaring with self-induced rage as he came.

Like all the men of our horde, when they were angry or were trying to make themselves angry, he stopped now and again to hammer on his chest with his fist.
I realized the helplessness of my situation, and crouched trembling in the nest.