Evidence of mate choice copying in Norway rats, Rattus norvegicus

In the literature, nonindependent mate choice of females is frequently referred to as ‘mate choice copying’. The label seems particularly appropriate when the probability that a focal female will mate with a male increases after she has watched him engage in sexual behaviour with another female. However, the classic definition of mate choice copying requires only that a male's attractiveness to a female change following his acceptance or rejection by another female regardless of whether such alteration in a female's response results from seeing him mate or from some other process. Here, we provide evidence that female Norway rats prefer to affiliate with a male that has recently engaged in sexual activity, even when they did not observe the male's previous mating. Furthermore, when we provided oestrous females with access to two males tethered some distance apart, the male that had recently copulated also mounted and achieved intromission and ejaculation sooner and more frequently than the male that had not recently copulated. We also provide evidence that increased attractiveness of male rats that had recently copulated was mediated by olfactory cues, and that female rats tended to affiliate with males that had engaged in sexual activity but not with males that had spent time with anoestrous females.