Prairie vole fathers from the non-separated, VEH-treated mothers (see Fig. 4) were monitored for their affiliative behavior before and after removal of their lactating female partners to determine possible effects of the procedure on the fathers. Indeed, immediately after returning the female partners (+30 min), prairie vole fathers dropped in the occurrence of blanket posture on the pups/being in contact with the nursing mother (blanket/contact) and total sum of parental behavior (on nest), whereas self-, but not partner-, grooming was increased. For further details, see legends to Fig. 4. Data are presented as mean + SEM, n = 6. ** p < 0.01 versus pre-infusion time point.