ridges that cast them. Tracking is easiest in the morning and late afternoon, as the shadows cast by the ridges in the spoor are longer and stand out better than at or near midday. As the sun moves higher in the sky, the shadows grow shorter. At midday the spoor may cast no shadows at all, making them difficult to see in the glare of the sunlight. Trackers will never look down at their feet if they can help it, since this will slow them down. By looking up, well ahead of themselves, approximately five to ten meters (15–30 feet) depending on the terrain, they are able to track much faster and with more ease. Unless they need to study the spoor more closely, it is not necessary to examine every sign. If they see a sign ten meters ahead, those in between can be ignored while they look for spoor further on. Over difficult terrain it may not be possible to see signs well ahead, so trackers will have to look at the ground in front of them and move more slowly. Trackers must also avoid concentrating all their attention on the tracks, thereby ignoring everything around them. Tracking requires varying attention, a constant refocusing between minute details of the track and the whole pattern of the environment. Anticipation and prediction Although in principle it is possible to follow a trail by simply looking for one sign after the other, this may prove so time-consuming that the tracker will never catch up with the quarry. Instead, trackers place themselves in the position of their quarry in order to anticipate the route it may have taken. They will thereby be able to decide in advance where they can expect to find signs and thus not waste time looking for them. Trackers will often look for spoor in obvious places such as openings between bushes, where the animal would most likely have moved. In thick bushes they will look for the most accessible thruways. Where the spoor crosses an open clearing, they will look in the general direction for access ways on the other side of the clearing. If the animal was moving from shade to shade, they will look for spoor in the shade ahead. If their quarry has consistently moved in a general direction, it may be possible to follow the most likely route by focusing on the terrain,