Home range size adjustments by the eastern chipmunk, Tamias striatus, in response to natural and manipulated water availability

Abstract

Capture–recapture techniques were used to study the spatial organization of a population of eastern chipmunks, Tamias striatus, over 16 weeks of an uncharacteristically dry summer and early fall. The objective was to examine the role of free water as a factor influencing home range size. Home range size was estimated for time periods of 1, 3, and 5 weeks. For animals captured more than two times, home range size estimates were not significantly correlated with the number of captures or body weight, nor did home ranges differ between males and females. Home ranges were relatively large in early summer, small in mid- to late-summer, and large again in the early fall. Home ranges were significantly smaller during the 8 weeks of greater-than-median precipitation than during weeks of less-than-median precipitation. Home ranges of 8 individuals out of 12 increased in size during a 3-week drought period relative to their pre- and post-drought home ranges. Differences in home range size between drought and nondrought periods were more pronounced for males than females. Comparison of home range size before and after the provision of supplemental drinking water showed that where water was added, chipmunks reduced the size of their home ranges significantly more than control (unwatered) chipmunks. These results identity water availability during certain years and seasons as a factor influencing home range size.