Relocation of nest sites is common among mice of the genus Peromyscus. We d
ocumented the occupation of artificial nest boxes by litters of white-foote
d mice (P. leucopus) at different stages of development to determine if nes
t relocation by lactating females is related to the developmental stage of
the offspring. Three stages of development (neonates, age 0-5 d; nestlings,
age 6-14 d; and juveniles, age 15-27 d) were recognized Although the nest
boxes were monitored at approximately weekly intervals, 72% of 134 litters
were observed during only one of the stages of development, indicating that
movement of young during lactation was common. Comparison of observed use
of the boxes at different stages of development of young to expected use in
dicated that use of boxes was not random. Boxes were used relatively infreq
uently by dams with neonates and nestlings and most frequently by dams and
juveniles. We believe that the suitability of a nest site to a lactating fe
male depends on the age of her litter and that the size of the nest cavity
may be an important factor in nest selection.