The tested the use of fluorescent powder to infer mating activity of m
ale rodents. The ventral surfaces of adult, male house mice (Mus domes
ticus) were dusted with fluorescent powder; the males were paired imme
diately with unmarked adult females for 6 days. Same males were dusted
once, others were dusted every day. The backs of females were checked
daily for transfer of fluorescent powder. We repeated the procedures
with female pairs in which one female was dusted either once or daily
as a control for transfer of powder due to noncopulatory contact. The
transfer of powder occurred more often in male-female pairs dusted onc
e than in female-female pairs. Our results support the use of fluoresc
ent powder to infer the activity of mating in male rodents.