Rat Social Interaction

Not all assemblies are social in the sense in which the term is used. Members of one species often associate because they all respond in the same way to some feature of their environment, such as a course of food. Perhaps rats are sometimes brought together by the amenities offered by a particular area. To be suitable for rats, a biotope must offer food, cover and nesting sities and material. For rattus norvegicus, cover may be (and away from building usually is) provided by earth burrows. We shall see however, that there are severe restriction on the extent to which strange rats can come together to form a stable group. Nevertheless, immature rats of both sexes, and adult females, could (as far as we know) from a colony in any area such as a large refuse dump, a glue factory, a food warehouse or a farm; throughout much of the world, all such places, in the absence of strenuous action by the human accupants, are liable to harbor large colonies of rats.

The social behavior of rats is often best studied in groups of wild individuals, either in conditions which approach the “natural” or in contrived situations which nevertheless permit the rats plenty of scope for varied behavior. Some experiment on laboratory rats, reviewed by Munn, failed to demonstrate any tendency to assemble. Rats were put in an apparatus in other experiments, rats were offered a choice between a compartment which contained both food and other rats, and one which contained only food. The only positive conclusion reached in these required was that rats posses a strong “exploratory drive.” The importance of choosing the right kinds of rats and the right conditions is shown in a further statement by Munn. Relatively little research has been done on social behavior in rats primarily because rats are not especially influenced by each other’s actions. The second part of this statement is mistaken. It arises from the concentration of psychological research on domestic varieties in conditions which leave little scope for social interactions.