Complex sentence: Then, one by one, the vulture picks off the baby swans, and at one point he picks up the black duck, but returns him, labeling the irked duck with a "4F" (unfit for military service).
Split into simpler sentences: Then, one by one, the vulture picks off the baby swans. He picks up the black duck, but then returns him, labeling the irked duck with a "4F" (unfit for military service).