Answer:
Dies half its life. Lives the rest. Dances without music. Breathes without breath.
I fly through the air on small feathered wings, seeking out life and destroying all things.
High born, my touch is gentle. Purest white is my lace. Silence is my kingdom. Green is the color of my death.
I sleep by day, I fly by night. I have no feathers to aid my flight.
Don't do this in the shallow end.
People take me on walks and I run and have fun. What am I?