Publication Date


Document Type


First Advisor

Brower, James E.||Southern, William E.||Zar, Jerrold H., 1941-

Degree Name

M.S. (Master of Science)

Legacy Department

Department of Biological Sciences


Peromyscus leucopus; Animal populations; Aggressiveness


The role of aggressive behavior in population regulation was investigated by establishing four populations of Peromyscus leucopus of known aggressive levels and determining their rate of population increase and the resulting spatial distribution patterns. Modified paired-encounter methods were utilized as reliable measures of aggressiveness. The presence of highly aggressive males in the populations was responsible for an increased number of attacks during social contacts as was indicated by the frequency of tail wounding. High aggression was also correlated with fewer young being born and a decrease in juvenile survival. Differences in the spatial distribution patterns among individuals in the two aggressive levels were observed; indicating an interaction between degree of aggressiveness and population dispersion. The type of dispersion pattern may influence the frequency of social contacts, thereby causing behavior changes in the subsequent generation. A feedback mechanism of behavioral regulation of population size was thus postulated.


Includes bibliographical references.||Includes illustrations.


53 pages




Northern Illinois University

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