SITE FAMILIARITY AFFECTS ESCAPE BEHAVIOR OF THE EASTERN CHIPMUNK, TAMIAS-STRIATUS

To investigate the effect of familiarity with the local terrain on the ability to escape predators, we recorded the type of refuge chosen and the distance and time required to reach it, for chipmunks escaping a pursuing human at different distances from their burrows. Chipmunks never used their burrow as a refuge unless the chase was initiated within 2.5 m of the burrow entrance. The final refuge was commonly farther than the burrow entrance. Chipmunks were most likely to take refuge in holes other than their burrow when chased within their home range, whereas they were most likely to flee up trees when chased outside their home range. Chipmunks released within their home range (10 m from burrow) took only half as much time and travelled only half as far to reach a refuge as they did when released outside their normal home range (100 m from burrow). However, there was no effect of distance on time and distance to a refuge within the home range (1.3-17 m). This appears to be the first experimental field evidence that animals are better able to evade pursuit in areas they use more frequently and suggests that specific knowledge of the terrain facilitates this more effective evasion.