Home Ranges and Territorial Behavior of the Yellow-Pine Chipmunk, Eutamias amoenus

About 600 chipmunks, Eutamias amoenus, were live-trapped and observed on a study area of 42 acres in yellow pine forest in central Washington. Observation of dyed chipmunks showed that home ranges revealed by live-trapping are reasonably accurate. Evidence that male yellow-pine chipmunks are more active and have considerably larger home ranges than do females is consistent with studies of other mammals. Annual home ranges of adult males averaged 947 by 534 feet and covered 4.07 acres; those of adult females averaged 686 by 368 feet and had a mean area of 2.32 acres. Some ranges were elongate despite a relatively uniform habitat. Adult breeding females had an average of 6.4 neighboring females overlapping their home ranges, the mean area of overlap being 21.7 per cent and number of captures 25.8 per cent. Most chipmunks that were recaptured in the second and fifth years occupied their original home ranges. In 43 homing tests 88 per cent (15 of 17) of the chipmunks returned from points 430 to 1500 feet from home, 57 per cent (12 of 21) from half a mile, and 25 per cent (one of 4) released 1 mile distant. Seventy-seven per cent of the males but only 25 per cent of the females returned half a mile. A shift of home range was accomplished by 7.8 per cent of the females and 11.9 per cent of the males recaptured the second year. Twenty-eight per cent (13 of 46) of the young animals caught in June and July were recaptured in the autumn. Evidence from spacing of chipmunks and from observations of aggressive behavior near the den indicated that they are territorial.