Social Signals of Rat

Tactile Signals
The signals on which we are best infomed act through contact or vision. This is because they are the most easily studied by the microsmatic adult human observer which an upper hearing limit of about 18 kHz. We begin with an example which does not constitute a simple, well defined stimulus.

Huddling is one of a number of ways in which rats derive cutaneous stimulation from each other. Soulairac has published a formal account of the familiar huddlling behavior of laboratory rats. He allowed a group of four was opportunity to separate into isolated individuals or pairs, the rats slept together in a group. Only parturient females isolated themselves. Similar observation have been made of wild rats in large cages, which they explore. Later they sleep or rest in groups eigther in nest boxes or in the corners of the main cage. This behavior is not merely a product of the shelter or tactile stimuli offered by these places; if rats do rest on the cage floor, they usually do so together in one corner; the chosen corner may vary, but the grouping remains rather constant. Similarly, when several nest boxes are available, only one or two may be occupied, when more than one, each is as a rule used by a group.

Huddling is often supposed to have a heat conserving function. Certainly the heat provided by other animals is sometimes important for small mammals, including rats and mice. Nesting rats especially depend on heat from their mother, since they cannot regulate their own temperature until they are at least eighteen days old. The colder the environment, the more important an external source of heat become. Nevertheless, in ordinary conditions in the laboratory, huddling has no energy conserving effect, yet it still occurs.