Ventral marking in the male Mongolian gerbil reflects present and future reproductive investments

Ventral scent-marking in the male Mongolian gerbil, Meriones unguiculatus, may be related to reproductive potential. In four experiments involving nine groups, males' marking during 5-min. open field tests correlated with their social and reproductive status. The lowest levels of marking occurred among individually housed or subordinate males of a pair, followed by males exposed to ovariectomized females, and dominant males of a pair. Higher levels of marking occurred with vasectomized males living with intact females or following the removal of males from a nuclear family. The most frequent marking occurred when males were housed with pregnant females and with females and their offspring. The proximate stimuli leading to high marking appear to be the sexual availability of reproductively competent females.