Fig. 4From: Automatic detection of small PIT-tagged animals using wildlife crossingsA selection of three toad trajectories in the tunnel. The x-axis shows the time (in minutes) from release; the y-axis shows the distance travelled (in metres) from the entrance. Black line = observed trajectories; diagonal dotted line = theoretical trajectories assuming a constant speed; circles = detection events (four detectors); horizontal dotted line = detector’ position in metres from the entranceBack to article page