Figure 3.

Behavior with access to shelter. Each graph represents the activity of one vole that was tested with a shelter. The traveled distance (in cm.) is shown for each minute of observation. In the top graph, activity during Pre-appearance (left portion of the graph) ceased to zero when the owl appeared and the vole entered the shelter (11 min). At 63 min the vole left the shelter for another period of activity, matching the level of the Pre-appearance period, despite the exposure to the owl. The vole then re-entered the shelter, taking only frequent short-distance trips (risk assessments) to the outside (90–110 min), followed by inactivity (110–148 min). The vole then again left the shelter (110) and was then caught during the first attack by the owl (151 min after beginning of observation). A second vole with the same behavioral pattern is shown in the bottom graph. Its initial activity (1–13 min) ceased when the owl appeared and the voles stayed in the shelter with few stretch attempts to the outside (13–37 min). It then resumed activity in the outside (37–101 min), followed by a long pause in activity (101–184 min). The vole then left the shelter and was caught by the owl.