Wood mouse

Diet

Wood mice are primarily seed eaters, particularly seeds of trees such as oak, beech, ash, lime, hawthorn and sycamore. If seeds are plentiful on the ground, they carry them back to their nests/burrows for storage. They may eat small invertebrates such as snails and insects, particularly in late spring and early summer when seeds are least available. Later in the season they will eat berries, fruits, fungi and roots. In winter, they may prey on hibernating bats, but this is still debatable.

Behaviour

Wood mice are mainly active during the dark, probably having evolved so to avoid predation, employing several anti-predatory strategies, though breeding females may be more active in daylight in order to collect sufficient food. While foraging, wood mice pick up and distribute visually conspicuous objects, such as leaves and twigs, which they then use as landmarks during exploration. If a wood mouse is caught by its tail, it can quickly shed the end of it, which may never regrow. Despite its name, it prefers hedgerows to woodland. During the colder months, wood mice do not hibernate; however, during severe winter seasons they can fall into a torpid state, a decrease in physiological activity.

Predation

Predators of wood mice include foxes, snakes, weasels, cats, dogs, and birds of prey such as owls.

Reproduction

The wood mouse has a breeding season from February to October in which multiple matings occur between males and females, resulting in scramble competition. Such behavioral characteristics result in sperm competition and multiple paternity litters. The society is polygynous with copulation resulting from scramble competition during reproductive periods. Males possess a sac known as the cauda epididymis, which stores sperm and lies underneath the scrotal protrusion. Temperature regulation ensures maximum sperm output.

One interesting observation about the species, in particular the males, is the morphology of the spermatozoa. They develop falciform (sickle-shaped) heads after meiosis and before spermiation (release during ejaculation). The hook located at the tip of the head adheres to the surface of the head prior to deployment. Propidium iodide staining revealed that only the basal surface of the hook is of nuclear origin. These apical hooks are deployed in the female reproductive tract (the mechanism responsible involved the remodeling of actin filaments in the hook). Deployed apical hooks combine with apical hooks and flagella of other spermatozoa. The aggregates of spermatozoa that result in form "mobile trains", which have experimentally been determined to possess better motility in the female reproductive tract. The mobility of these mobile trains was also found to be influenced by premature acrosome reactions, altruistic acts performed by some spermatozoa for the benefit of other genetically similar gametocytes. This altruism follows a "green beard" mechanism in which spermatozoa discern the genetic similarity of surrounding gametocytes (such mechanisms are rare because they must code for a recognizable phenotype, as well as response mechanisms). Once spermatozoa of similar genotypes are identified, altruism genes are turned on to elicit a response that seeks to conserve the genes present in the other cell, even if it results in the destruction of the cell performing the action.

The gestation period of wood mice is of 23–27 days and each female produces on average four young per year. The offspring become independent after about three weeks and become sexually active after two months.