Seasonal Influences on the Movements of Bush Rats, Rattus fuscipes, in an Artifical Environment

Abstract

Australian bush rats, Rattus fuscipes, were observed singly, each in an artificial environment (a plusmaze) consisting of a central nest box with four arms radiating from it. One arm contained food, one water, and the others were empty. Movements were recorded automatically. Each maze was kept at a constant ambient temperature of about 22°C. Before testing, rats of group I were housed in a room also at 22°C, with lighting altered to match seasonal changes; rats of group II were kept in natural conditions of temperature and light, but under cover. Both groups made fewer visits to the empty arms, and spent less time in them, in winter than in summer; but the rats of group I1 made more visits to the empty arms, in both seasons, than did those of group I. Most visits to the arms were brief. Long visits to food or water were followed by a series of short visits to the arms. In summer, first short visits after eating or drinking were often to the empty arm ('exploration'); but in winter they were more often to the food or water arms ('foraging'). It is suggested that the change in pattern of movement between seasons represents the development of a new habit, as part of adaptation to change of temperature, and that the habit is retained for some time in a constant, warm environment.