And its mostly to annoy her mother in the car, and her sister and brother. Because neither of them can whistle, and there is a special kind of joy and pride being the middle child when you find something your older sister can't do. :) She is so serious about this whistling, she does it all day the same exact note. Her father gave her this idea, he told her to practice. (He and I will be speaking about this later). She is getting quite good, although I think she is hitting notes that only dogs can hear sometimes.