Urination as a Social Response in Mice

Abstract

SOCIAL identification in mice appears to be based largely on the odour complex presented by an animal. The exact nature, as well as the relative importance and signal function of its components—metabolic, glandular and environmental—are still being investigated¹, but their efficacy as olfactory cues is reduced by applying scent to an animal² or by dabbing a mouse with the urine of another, which tends to elicit from conspecifics social responses in accordance with the “urine label”^3–5, at least as far as fighting or exemption from it is concerned. This suggests that the odour of urine present in some quantity overrides other olfactory cues, and that there may be a relationship between social behaviour and the extent of concurrent elimination. Although the active use of urination in territorial marking has long been known⁶ and its occurrence in “open field” tests, where it is generally regarded as a fear response or an index of “emotionality”, has received much experimental study, less is known about its incidence and import in social contexts, and the experiments reported here—carried out as part of a study of social sniffing—are an attempt to examine this point.