Although similar in appearance and, in some cases, size, mice and shrews are different creatures. They don't belong to the same scientific order, despite superficial resemblance to one another. The distinctive traits of each animal may outnumber their similarities.
Comparison of a Shrew & a Mouse
Domesticated or Not
Not all mice are domestic species, and no shrew is truly a domesticated species. As pets, mice are curious, affectionate and playful creatures. They rely on many of their natural instincts even in captivity, including gnawing, burrowing and hiding. In the wild, most mice are skittish and reluctant to interact with humans.
Some shrews, however, have been known to be aggressive to humans. Shrews are not pets and their behavior and instincts make them a poor choice for a companion.
Behavior and Diet
Although different, mice and shrews sometimes share similar behaviors. For example, many shrews are nocturnal and so are many wild mice; some species of each, however, are diurnal. Mice tend to be social creatures, although not every species is. The house mouse (Mus musculus), the species most domestic mice belong to, is quite social. In the wild, many mice have a preference for seeds and nuts; fruits, insects and greens sometimes make their ways into a mouse's diet.
Many shrews are solitary creatures, although some are semi-social, including the least shrew, which sometimes nests with multiple members of the same species. They will seek out insects and arthropods; some will even eat birds, mice and other shrews.
Domestic Mouse Diet
Owners of pet mice have a wide range of nutritionally complete and balanced foods available at pet supply stores. Because of their gnawing nature, it's a good idea to give your mouse "block" foods, which are pressed and have complete nutrition.
In addition to store-bought foods, give your mouse small portions of fresh vegetables such as carrots and broccoli.
North American shrews have widely diverse habitats, including nearly every type of terrestrial habitat. Water shrews, as their common name implies, prefer more marshy and wet habitats.
Common mice also have diverse habitats. The house mouse, for example, tends to live in close quarters with humans and relies heavily on humans for food and shelter.
Species in the genus Peromyscus, which includes white-footed and deer mice, have specialized habitats. White-footed mice tend to prefer wooded or brushy areas; deer mice are much more adaptable.
Domestic Pet Habitat
Plenty of space.
No holes or spaces larger than 1/4-inch.
Do not use wire cages.* Safe bedding, several inches thick.
Hardwood shavings.* Boxes and other hideouts.
In addition, your pet mouse should have a variety of safe chew toys, including apple branches, cardboard and mouse-safe items found at pet stores. A water bottle and food dish are necessary, as well. Because of their instinct to hide, nocturnal and crepuscular behavior, and curiosity, give your mouse tunnels, tubes and upside-down boxes or flower pots to run through, burrow in and hide under.
Temporary Housing for Injured Shrews
In the case you find an injured shrew on your property, fill the bottom of a large bucket with soil, leaves, moss and bark and wet it down to the point it is moist. Place some cotton wool in one area and place an overturned cardboard carton or similar item over it to make a nest site. Take the shrew to a licensed wildlife rehabilitator as soon as possible.
Mice and other rodents have distinctive incisors -- one pair on each jaw -- they use to gnaw. Rodentia also includes other common pet types, such as guinea pigs, rats, hamsters, chinchillas and gerbils.
Shrews and most other insectivores have pointed snouts and numerous sharp teeth, which help them eat their preferred food sources. Closely related to the shrews are hedgehogs and moles.