Analysis of maternal aggression in WT and CRFR1-/- mice. Using a resident-intruder paradigm, CRFR1-/- mice show decreased aggression relative to WT mice, but these difference do not reach significance in terms of the percentage of females showing any aggression (A), the average number of attacks (B), the average amount of time in aggressive encounters (C), and the average latency to first attack (D) when examined on either postpartum Day 4 or 5. Bars represent means ± SE. White bars indicate WT mice and black bars indicate CRFR1-/- mice. Data that were non-normally distributed were examined via non-parametric tests (see Methods and Results for more details). When a possible outlier from the CRFR1-/- was removed, significant differences in aggression were found for some measures (see Results for details).