Common Shrew

See also Masked Shrew for the mammal known as the Common Shrew in parts of North America.

The Common Shrew or Eurasian Shrew (Sorex araneus) is the most common shrew, and one of the most common mammals, throughout Northern Europe, including Great Britain, but excluding Ireland. The average shrew mesaures 55-82 mm in length and usually weighs 5-12 grams. Shrews are recognized by their velvety dark brown fur and pale undersides. Juvenile shrews have lighter fur until their first moulting, when darker winter fur grows in. The common shrew has small eyes, a pointed, mobile snout, and red-tipped teeth. The common shrew has a life span of approximately 23 months.

Shrews are active day and night, but mostly after dark. They are active most of the time, resting for only a few minutes between activities.

Territory

The common shrew is found in the woodlands, grasslands, and hedgelands of Britain, Scandinavia, and Eastern Europe. Each shrew establishes a home range of 370-630 metres for their entire lifetime. Males extend these boundaries only during breeding season, to find females. Common shrews are extremely territorial and become aggressive when another shrew enters a home range.

Common shrews make their nests underground or under dense vegetation.

Diet

The shrew's carnivourous and insectivorous diet consists mostly of insects, slugs, spiders, worms, and carrion. Shrews need to consume 80-90% of their body weight each day in order to survive. A shrew must eat every two to three hours to achieve this goal. They do not hibernate in the winter months because their bodies are too small to hold sufficient fat reserves.

Shrews have poor eyesight, but use their excellent sense of smell and good hearing to locate food. Using these senses, a shrew can locate prey up to 12 cm deep in the soil.

Breeding

The common shrew breeding season lasts from April to September, but peaks during the summer months. After a gestation period of 24 to 25 days, a female gives birth to a litter of 5-7 shrews. A female usually rears 2-4 litters each year. The young are weaned and independent after 22 to 25 days.

Breeding is the only time that shrews do not prefer to be solitary. Young shrews often form a caravan behind the mother, each carrying the tail of the sibling in front with its mouth.

Protection and population

The common shrew is not an endangered species, but is protected by the Wildlife and Countryside Act of 1981. It is an offence in Britain to kill a shrew without a licence.

In Britain, shrews can be found at densities up to one per 200 square metres in the woodlands. These population numbers are controlled by owls, weasels, stoats, and foxes, which prey on the common shrew. A liquid produced by glands on the skin make shrews rather unpleasant tasting to domestic cats.

There has been a recent decline in common shrew populations due to increased use of herbicides.

References

Database entry includes a brief justification of why this species is of least concern