Male and female mice scent mark during social communication regardless of sexual motivation or partner identity

Many species communicate via pheromone signals that orchestrate key social and survival behaviors. In laboratory assays, only male mice are observed to broadcast pheromones through urine scent marking. This has contributed to the view that males have specialized circuits and anatomy to intentionally transmit urine pheromones and actively participate in socio-chemical communication, while females remain mute recipients in laboratory settings. Here, we find that simple modifications to standard assays reveal exuberant urine marking by laboratory females, enabling reexamination of its dimorphic features. Chemogenetic inhibition of estrogen receptor-1-expressing (Esr1) neurons in Barrington's nucleus confirms that both sexes rely on a similar mechanistic strategy necessary for urine marking. Moreover, we find that males and females mark toward a broad set of receivers, including reproductively incapable partners. Sex parity in urine marking reframes the understanding of voluntary chemo-communication function beyond a male-specific behavior to a broader social communication strategy engaged independent of sex or reproductive status.