Fig. 5. Direction of movement of garter snakes (Thamnophis sirtalis parietalis) with respect to the main axis of the gravel road. The lower graph shows data for snakes scored as they approached within 1 m of the road, coming from the adjacent den. The upper graph shows data for snakes scored as they actually crossed the road. For both approaching and crossing snakes, the angle was calculated perpendicular to the main axis of the road (i.e., a snake proceeding directly across the road, at right angles to the main axis of the road, would score 0°).