Reproductive success diminished following mate loss for females but not males in a monogamous rodent.

The strictly monogamous California mouse (Peromyscus californicus) forms life-long pair bonds and mates exclusively with a single partner. While studies in the wild indicate that individuals may re-pair with a new partner following mate loss, the preponderance of this behavior and subsequent reproductive outcomes following re-pairing are understudied. To examine reproductive outcomes following re-pairing and to look for sex-specific differences following mate loss, birth records of 584 California mouse pairs from our laboratory were analyzed. Of these pairs, 59 pairs were identified as re-pairs and used for further descriptive analysis. We found that 50/59 (84.7 %) of re-paired animals gave birth, indicating that reproduction with a new mate is not only possible, but perhaps more common than previously described for this species. Additionally, we found that when re-paired, females took significantly longer to birth a subsequent litter as compared to original breeding pairs. Overall findings from the current study provide evidence for sex differences in reproductive outcomes following repairing and for greater flexibility in mating strategy for a species described as strictly monogamous.