Salt water harvest mice swim and climb very well. They do not dig burrows. Instead the build grass nests, or reuse abandoned bird's nests.
Salt water harvest mice spend most of their time hiding in the protection of dense marsh vegetation, especially pickleweed. They are mainly active at night, and they are active year around.
The Western Harvest Mouse lives in all European countries except for Ireland, Spain and Scandinavia. It also lives in Siberia, China, and Taiwan.
The western harvest mouse has unique feet. Their hind feet have five toes, while their front feet only have four.
The wood mouse stores food in underground burrows. Food remains are found in disused bird nests, on tree stumps and in sheltered feeding places between the roots of trees or under ledges. They tend to leave the flesh of fruit and eat only the pips.
Wood mice eat seeds, green plants, fruits and animal foods. In a mixed deciduous woodland they eat acorns, ash and sycamore seeds for most of the winter, buds in early spring, caterpillars, worms and centipedes in early summer and blackberries and fungi in the autumn.
The harvest mouse has a short lifespan. It can live up to 18 months in the wild, but usually 6 months, but it can live up to 5 years in captivity.
The harvest mouse prefers areas of tall grasses. These areas include cereal crops (particularly wheat and oats), roadside verges, hedgerows, reedbeds, dykes and salt-marshes.
In contrast to lower vertebrate and invertebrate embryos, the mouse embryo develops from the zygote without any endowment of positional information from the mother.
Mice have hair that grows and then regresses. This hair follicle cycle is called the hair cycle.