California Mouse - Natural History

Natural History

The California mouse is semi-arboreal, but tends to nest on the ground, under debris such as fallen logs. Nests are insulated with coarse dry grasses, weeds and sticks, and fine grass is used as bedding in the center chamber. P. californicus is more strongly territorial than P. maniculatus with both sexes defending the nest site. Males are also aggressive toward one another; their fighting techniques involve jumping, avoidance and a characteristic mewing cry.

The California mouse pair bonds and the males help raise the young. A litter usually consists of only two pups, but a pair may produce as many as six litters in a year. Gestation ranges from 21 to 25 days. Weaning occurs when the offspring are 5 to 6 weeks of age.

The mouse's diet consists of shrub fruits, seeds, and flowers, such as of Rhus integrifolia, Lotus scoparius, and Salvia apiana. They will also consume grasses, forbs, fungi, and arthropods.

P. californicus is mostly active at night. The main predators of the California mouse are weasels and barn owls.