Social Density Modulates Male Courtship Behaviour Independently of Female Familiarity in Albino Mice Mus musculus

Abstract

Understanding how social and ecological factors shape male reproductive behaviour in group-living mammals is a key question in behavioural ecology. This study examined whether prior familiarity with a female and social group density influence male courtship behaviour in albino mice Mus musculus, and whether these two factors interact. A controlled experiment used three density levels (small, medium, large) with a constant 1:1 sex ratio. Before trials, each female was exposed to olfactory cues only from the familiar male via his soiled bedding for six days; the unfamiliar male’s scent was not presented. Courtship behaviour was recorded in the home terrarium for fifteen minutes per hour from early morning to late afternoon. The analysis yielded three principal findings. First, male courtship rate varied markedly across densities, being highest under medium density, lower under small density, and lowest under large density, thereby  indicating a non-linear relationship. Second, familiarity status (familiar versus unfamiliar) did not produce a significant difference in courtship rate within any density group, nor did it interact with density. Third, a consistent diurnal pattern was observed,  characterized by a courtship peak during early morning, followed by a steady decline through midday and afternoon across all densities. These results demonstrate that group density, but not prior familiarity with a female, significantly modulates male courtship effort in albino mice. The absence of a familiarity effect suggests that males do not adjust courtship intensity based on individual recognition under these conditions. The density-dependent pattern supports the concept of an optimal intermediate social density for reproductive behaviour.