The field of this invention is recording motion of an animal, uniquely identifying the animal, and recording an activity of that animal. Motions of animals on a path when the animal is or can be uniquely identified are tracklets. Tracklets begin and end at ambiguation events, where these are defined as locations and times of an animal where it cannot be uniquely identified. A first animal may be uniquely identified by first identifying all other animals in the first animal's environment. Animal identification may be after the end of a tracklet. Embodiments use optical flow analysis from video of an animal's environment. Embodiments record an animal's activity on tracklets and then use that activity to measure animal health or use that activity as data for a study using animals.