Female mound-building mice prefer males that invest more in building behavior, even when this 1 behavior is not observed 2 Abstract 9 Through behavioral correlations, mate choice could influence the evolution of traits that are not 10 directly selected for, or even observed. We addressed whether mound building, a unique collective 11 behavior observed in Mus spicilegus, could be favored by female mate choice, irrespective of whether 12 females were able to observe the behavior. First, we introduced mixed sex groups of wild-born mice in 13 large terraria with building materials, and assessed male variation in building investment. Second, we 14 presented females with a choice between males that invested the most versus the least in building. 15 Females were either able to observe the males during building or not. Third, because overwintering 16 juveniles rely on mound protection, we hypothesized that building could be a form of paternal care, 17 and assessed whether males that invested more in building also invested more in direct offspring care. 18 We showed that females were more attracted to males that invested the most in building, even when 19 these behaviors were not observed. In addition, direct offspring care was negatively correlated with 20 males' investment in building, suggesting that two alternative paternal care strategies (mound building 21 versus direct offspring care) may exist. Our study supports the hypothesis that building could be 22 detectable by phenotypic cues that differ from building behavior per se and that mate choice may 23 influence the evolution and maintenance of mound building that several authors describe as a common 24 good. 25 26