Head and body length of Peromyscus species range from
70-170 mm and tail lengths are 40-205 mm. There are 2 subgenera
and 55 species. P. californicus
has soft dense fur and large ears which are covered with fine
hairs. The tail is about one third the length of the total length
of this mouse, and is also covered with fine hairs. Females
have four or six mammae.
The preferred habitat is deep woodlands and brushy areas. Several
nest are built each year and are line with soft down from plants
or other materials which are shredded. Once a nest is soiled
it is abandoned and another is constructed. P. californicusis
primarily nocturnal and active year round, though periods of
torpor occur for several hours, during which time there is a
drop in body temperature.
diet consists of a wide variety of foods including nuts, berries,
fruits, insects, other small invertebrates, and carrion.
have shown that a paired male and female P. californicus
will live together cooperatively raising offspring. males are
highly aggressive toward one another. Estrous
cycles last an average of 7 days, gestation periods range from
21-27 days and averaging 23.4 days in non-lactating females.
Lactating females can have gestation periods of up to 40 days..
Litter sizes vary by region, with those in the northern areas
being larger. Overall litter sizes for Peromyscus genus
is 3.4 offspring weighing 2.2 grams. Most young are weaned at
3-4 weeks and stay with the mother for another month.
californicus occurs from C and S California, USA, excluding
the San Joaquin Valley, to NW Baja California Norte, Mexico.