Hypothesis on why you think the kites (type of predatory bird) spent the majority of the time active perching

Kites most likely spent the majority of the time active perching because they were actively looking for prey from an arial angle which allowed them to scope out their next victim

When the ball is rising up, it gains kinetic energy. when the ball reaches the very top, it will have all potential energy, until it falls back down and gains it kinetic energy. finally when you catch the ball or it falls back down, it would have gained its potential energy back.