The establishment of dominance hierarchies over concentrated food sources among Eastern Chipmunks (Tamias striatus).

Abstract

Among chipmunks, competition over concentrated food sources has often been observed. Aggressive behavior is commonly displayed within an individual's territory between and within species. However, though sex, size, age, and individual variation are speculated to be factors in establishing dominance over a concentrated food source, the bases for the establishment of dominance over concentrated food sources in Tamias striatus remains questionable. This study tested the hypothesis that: When a concentrated food source is placed equidistant from two or more chipmunk burrows, dominace over the food source will be established based on one or more of the following: first individual to encounter the food source, sex, and/or size (weight). After testing 6 sets of interactions with 6 chipmunks each, it was found that although aggression varied significantly with weight difference between winner and loser (p<.05), a linear relationship did not exist. As interactors got closer in weight, intensity of aggression did not increase. Because only one chipmunk of the 6 was male, any correlation between sex and dominance could not be examined. In addition, because the sample size was so limited, any correlation between first individual to encounter the food source could not be examined. Overall, much aggressive behavior might be attributable to individual variation. Future studies might increase sample size and would further contribute to our knowledge of the bases for dominance in chipmunks.