Environmental regulation of reproduction in an opportunistic breeder: the musk shrew (Insectivora: Suncus murinus).

In summary, photoperiod, social cues and food availability impact upon the reproductive system of the male musk shrew to alter the timing of reproductive maturation and hence opportunistic breeding. We can speculate that there might be a hierarchy to these environmental inputs. We suggest that for shrews living on Guam, food availability is the primary cue, whereas social and photoperiodic signals play modulatory roles. The relative importance of these three external cues most likely depends upon the evolutionary history and current habitat of the organism. In conclusion, opportunistic breeders, such as the musk shrew, may be excellent models for studying the integrative effects of multiple environmental signals on the timing of reproduction.