The owl tracks the mouse, not the blowing leaf. The outfielder tracks the fly ball, not the bird flying by. The jet fighter tracks the strategic missile launcher, not the school bus. Tracking is inexorably tied to object recognition. It is important to track the pickup truck headed straight toward the tactical operation center, not a similar truck headed into the farm field. So, it is not only the identity of the object that is important, but also the activity that the object is engaged in.