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Ancestor: Mus musculus interstellaris (Ship Mouse)

Descendants 2 Myh: 

Gupes
Nest Death Mice
Ratmouse
Louse Mice

Size: Origin Plains Mouse: 10 cm without tail (19 cm with tail), Subtropical Woodland Mouse: 8 cm (15 cm), Desert Mountain Mouse: 9 cm (17 cm), West Plains mouse:13 cm (24 cm)

Dietary Needs: Invertebrates make up the bulk of their diet. These include: Earthworms, beetles, woodlice, gnats, moths and butterflies. Unlike other mouse species, these mice will eat the adults and not just the maggots and caterpillars. They eat increasingly more plant matter as they get older, such as fruit, seeds and grains, but pups weaning off milk will start on soft-bodied invertebrates and work up to tougher foods gradually over the rest of their lives.

One major dietary exception is adult bees, which they are frightened to get up close to and will not hunt.

Although aquatic prey doesn't make up a large percentage of their diet they do occasionally eat river snails, crayfish larvae and young fish if they are met with the opportunity.

Life Cycle: While smaller species reproduce quickly and can give birth multiple times a year, larger species require more time to grow and this may be reduced to up to three litters a year. Due to a lack of a freezing winter reproduction can continue year-round. Dry seasons can lead to droughts, and female mice temporarily shut down fertility or eat their pups during the most extreme times. In this sense the pups can serve as living energy reserves if the mother's situation becomes dire.

Males use ultrasonic calls to attract females to mate. Male parental involvement varies by species, and it ranges between absolutely no involvement, to forraging for the mother and defending the nest. Fathers don't usually interact with the pups, but will usually freeze when approached or interacted with by the pups, as he recognises himself off their scent. This effect wears of once they reach older adolescence and their father will treat them all as competition, including the females. This pushes them to spread out of the territory of their birth and prevents inbreeding related genetic problems.

It takes most members of this species around  a month to reach sexual maturity, but for slower growing, larger species this maturation time can be closer to two months.

Other: The maxillary bone (and part of the lower mandibular that holds the lower molars) is slightly longer than that of the ancestral mouse. This is a feature all species in this genus have to varying degrees, and they are defined by it. The molars have lengthened to occupy a longer socket along the maxillary so that there is a smaller diastema between their molars and incisors - so the face is not usually longer except in a few species, but in most species it is more reshaped than resized.

This species of mouse eats a greater number of invertebrates, for which a large gap in between the molars and incisors is unsuitable for. This is because at times they may be rooting for invertebrates nose-in-the-dirt, or otherwise nose and whiskers first to home in on a suspected detection. While the incisors are powerful and capable, they require precision. The extension of the molars closer to the incisors shrinks a gap which strong and fast invertebrates such as beetles can escape, requiring more energy and struggle for the mice to subdue. Also, sometimes of the beetle is moving quickly the incisors can sometimes glance off to the side instead of piercing the carapace. In essence mouse incisors are great chisels but not suited for this particular job. In this genus, the molars are more likely to be able to pinch their prey in the initial struggle and prevent escape. The increased success in catching invertebrates is a form of positive behavioural reinforcement that encourages mice to seek more invertebrate prey, closing an evolutionary feedback loop.

The cusps are more pointed on one half of the tooth closer to the cheek to trap fast-crawling and wriggly prey, while the other half of the tooth closer to the tongue has more dome-like cusps to grind down the exoskeletons to make them safer to pass through the digestive tract. The masticating surface on the last molar at the back of the mouth has a more ancestral structure, and more plant matter is ground up here.

The genus is also defined by their varied proficiency in digging, and a peculiar dirt-scraping habit where they rake the claws on their forepaws across the ground. Because many invertebrates live in the soil the ability to dig or rake them up is often beneficial in finding them. They also use their foreclaws to pry apart incredibly soft and rotted wood, as there are likely woodlice living in the cavities beneath.

When digging in soil they may also unearth bonus seeds and tender seedlings which they will also eat. Some can dig burrows to raise their pups, while some don't dig much except to disturb the leaf and humus layer of the soil, because in some environments this is enough to find food that they need. In the example species the west plains mouse is a burrower and (when pup raising) and heavy scraper, while the woodland mouse does not need to burrow to find nesting places and can find food with less effort due to greater abundance than in drier places. They rummage more than they scrape. The desert mountain mouse can burrow, but must be adaptable about their nest-making when there isn't suitable soil. they and the origin plains mouse do scrape, but not as often or as intensively as the West plains species.

Lastly, this genus is generally good at skipping, jumping and fast sprinting. Their hind foot is somewhere between digitigrade and plantigrade, often switching between the two depending on the usage situation. The grasslands and scrublands can require much speed and energy to cross, or to reach one safe place to another, so a spring in their step helps. There has also been continued selection against mice that are too slow to process a cat's sudden pounce at them until it's too late, and for mice that can spring away at lightning speed at the first suggestion of danger.