Tracking in hunting and ecology is the science and art of observing animal tracks and other signs, with the goal of gaining understanding of the landscape and the animal being tracked (the "quarry"). A further goal of tracking is the deeper understanding of the systems and patterns that make up the environment surrounding and incorporating the tracker. The practice of tracking may focus on, but is not limited to, the patterns and systems of the local animal life and ecology. Trackers must be able to recognize and follow animals through their tracks, signs, and trails, also known as spoor. Spoor may include tracks, scat, feathers, kills, scratching posts, trails, drag marks, sounds, scents, marking posts, the behavior of other animals, habitat cues, and any other clues about the identity and whereabouts of the quarry. The skilled tracker is able to discern these clues, recreate what transpired on the landscape, and make predictions about the quarry. The tracker may attempt to predict the current location of the quarry and follow the quarry's spoor to that location, in an activity known as trailing. Prehistoric hunters used tracking principally to gather food. Even in historic times, tracking has been traditionally practiced by the majority of tribal people all across the world. The military and intelligence agencies also use tracking to find enemy combatants in the bush, land, sea, and desert. Tracking as an art and science It has been suggested that the art of tracking may have been the first implementation of science, practiced by hunter-gatherers since the evolution of modern humans. Apart from knowledge based on direct observations of animals, trackers gain a detailed understanding of animal behavior through the interpretation of tracks and signs. In this way much information can be obtained that would otherwise remain unknown, especially on the behavior of rare or nocturnal animals that are not often seen. Tracks and signs offer information on undisturbed, natural behavior, while direct observations often influence the animal by the mere presence of the observer. Tracking is therefore a non-invasive method of information gathering, in which potential stress caused to animals can be minimized. Some of the most important applications of tracking are in hunting and trapping, as well as controlling poaching, ecotourism, environmental education, police investigation, search and rescue, and in scientific research. The modern science of animal tracking is widely practiced in the fields of wildlife biology, zoology, mammalogy, conservation,