Behavioural comparisons of isolated, dominant and subordinate mice.

The study examines the suggestion that isolated male mice act in a similar way to dominant males. Behaviours of isolated, dominant and subordinate mice were compared in an open-field, emergence test, activity monitor and aggression test. In a number of ways the behaviour of both isolates and dominants differed from subordinates. Subordinates were more active on the first day in the open-field, but they habituated relatively quickly. In contrast, both the isolates and dominants were initially relatively inactive, but reacted to a novel situation for longer. There were, however, no circadian variations in activity in the three categories of mice. Unlike the subordinates, both dominants and isolates displayed aggression towards male mice; these last two categories of mice also had heavier sex accessory glands. It was concluded that the behaviour of isolated and dominant mice is very similar, at least under the conditions of this experiment.