| Abstract: | Male mice of the CF-1 strain (Mus musculus) were allowed to take up lone residence in a small territory consisting of a 60-cm enclosure attached by a tubular runway to a standard mouse cage with food, water, and bedding. A group of ten mice, each of which resided in its own separate enclosure for 24 hours, were more aggressive toward intruders than other groups of ten mice following six-hour residence periods, or no such residence. Aggression toward intruders increased in repeated weekly tests of the six-hour residents, but after four weeks of testing did not reach the maximum stable level displayed by the 24-hour residents over four weeks of testing. In another experiment, the 24-hour residence period of groups of 20 CF-1 male mice was disturbed by briefly removing the mouse from the enclosure, before introducing the intruder, at various intervals prior to testing. Removal of the resident five minutes before testing resulted in a marked decrease in aggression toward intruders. Although lesser decreases in aggression followed intervals of 30, 45, and 60 minutes, a 180 minute interval resulted in no appreciable effects compared to undisturbed controls. It is concluded that exposure to the stimuli provided by the enclosure results in an aggressive readiness in the resident mouse which reaches a high level within a 24-hour period. |
