Species: Sorex araneus
IUCN Status: Least Concern
Population Trend: stable
Distribution: Widespread throughout Britain but absent from Ireland.
Habitat: Common in hedgerows, fields and woods but scarce on moorland.
Description: Long, pointed nose, tiny eyes and small, rounded ears set close to its head. Short, dark brown velvety fur, lighter flanks and grey underparts.
Size: Head and body about 76mm (3in), tail 40mm (1in). Weight about 7g.
Life-span: Up to about 20 months; most die before they are a year old.
Food: Earthworms, insects, slugs, snails, woodlice and some carrion.
The common shrew is one of Britain's smallest mammals (the pygmy shrew is the smallest mammal of all) and is closely related to the mole and hedgehog - not the mice, as people sometimes think. Its pointed nose distinguishes it easily from mice.
Shrews are not often seen because they spend most of their time underground. They are mainly nocturnal but are often about during the day; their high-pitched squeaks can be heard as they scurry along tunnel-like runways through the grass, leaf litter or soil. A shrew is always on the go, twittering and poking its long nose here and there as it forages for food. It has a short rest every hour or two, but uses up so much energy in its busy life that it will starve to death if it goes without food for more than three hours.
Earthworms are one of the common shrew's main foods but it eats many other small invertebrates, consuming almost its own weight every day. The shrew finds its food mainly by using its keen sense of smell - it has poor eyesight; long whiskers help it find its way about.
A shrew cannot bear to have another in its territory, except at breeding time, and if two shrews meet along the same tunnel they touch whiskers and squeak; if the intruder does not retreat both rear up on their hind legs and squeak more loudly; if this has no effect, they both fall onto their backs, wriggling and grabbing each other by the tail, squeaking even more loudly! They rarely hurt each other - it's more of a squeaking contest than a fight!
Many shrews are eaten by a variety of predators, including owls, hawks, magpies, jackdaws, weasels, stoats, adders and smooth snakes. Cats kill large numbers too, but rarely eat them because the shrew's skin has foul-tasting glands which also give it a nasty smell! Some other predators also probably find shrews distasteful.
Shrews do not hibernate but spend the winter in hedge-bottoms and copses among the dead leaves. In summer they spend more time in grassy fields and rough pastures. A shrew sometimes even climbs grass stems after insects and has been known to climb a tree, up to 3 metres in height, looking for food. It can spread its toes apart and this helps it to climb.
Common shrews breed from May until October and a female produces at least two litters during this time, each having from 4 - 10 young, the average being around 6. The young are born in a cup-shaped nest woven from dry grass and other plants; this has a loose roof through which the mother shrew comes and goes. To begin with the babies are naked, blind and deaf. They grow quickly and are independent at one month old.
Threats to the Common Shrew
Shrews are useful members of the wild mammal community because they eat invertebrates, many of which are regarded as pests by man. However, although the common shrew is probably one of Britain's most abundant mammals, it is thought that the population as a whole has been reduced over recent years. This is probably due to the use of herbicides (weedkillers) and pesticides. These toxic chemicals destroy the taller grasses and other plants which provide shelter from predators. Also they kill many of the invertebrates on which shrews feed. As of 2020 the IUCN has said that the population is stable but there may be local decreases due to degradation of habitat.
Shrews are partially protected under Schedule 6 of the Wildlife and Countryside Act of 1981 - this means they cannot be killed or captured using traps, snares, nets, or poisons etc.
Image: Shrew (Common) by Tony Sutton
Information sourced from:
The IUCN Red List of Threatened Species (2015), Sorex araneus [online], Available from: http://www.iucnredlist.org/details/29661/0 [accessed 12/08/2015].