Cornwall Mammal Group
Common Shrew-(Sorex araneus)
Order: Eulipotyphla, Cornish Name: Hwistel
Recognition:
Common shrews have small eyes and ears and a long pointed snout that is rather mobile. The head and body length is 48 to
80 mm, with a tail of 24 to 44 mm, less than 75% of the length of head and body. Adults weigh between 5 and 14 g. The short, velvet-like fur is dark brown with a pale underside, whilst juveniles are a lighter brown. Around 20% of the population has distinctive white tufts on their ears. The teeth are tipped red. Mature females can be identified by three pairs of nipples, whilst males in breeding condition show prominent bulges on either side of the abdomen that are their testes. On
occasion their high pitched squeaks can be heard from the vegetation. Although similar in appearance to the pygmy shrew, the common shrew is larger, while the pygmy shrew has a more domed head and a paler brown coat.
Common shrews are often found during checks on local dormouse nest boxes: these tiny animals often fill the boxes with loose masses of leaves and dry grass and may spend the winter in their
adopted tree houses.
Shrews are active all day and night, but usually under cover. Their tiny black crumbly droppings are rarely found and they leave tracks in only the softest and finest mud. However they are very vocal and their high pitched bickering and squeals can often be heard in hedgerows and dense grass. Placing corrugated sheets in unkempt areas to provide shelters (known as refugia) can attract shrews along with other small mammals. Shrews may also be disturbed when clearing garden rubbish. Common shrews make small loose nests of grass and other vegetation in tussocks and under cover. Larger, denser, breeding nests may also be found, occasionally quite deep underground.
© David Chapman
© David Chapman
Common shrews are found wherever suitable cover is available, most often in thick
grass, scrub, banks and hedges, and deciduous woods. They are also abundant in urban wasteland and roadside verges. They will occasionally enter houses and their ability to climb means they are often found in bird and dormouse boxes.
Common shrews prey on terrestrial invertebrates: the most important are adult beetles, insect larvae, worms and woodlice, but they will also eat slugs, snails, millipedes, centipedes, bugs and others. Shrews have a voracious appetite and need to eat 80-90% of their body weight per day. They feed every few hours and spend most of their waking hours foraging. Shrews mainly use their sense of smell, together with their touchsensitive snouts to locate prey. Once a food item has been caught the shrew immobilises it by biting its head.
Shrews mature in the spring, and then the males begin their search for mates. Females will often resist the male’s advances, which results in squeaking and scuffling. These sounds may sometimes be heard from the hedgerow. Only when in oestrus will the female be willing to mate. During mating the male will hold the female and often creates a small bald patch on her nape or the top of her head. After a gestation of around 22 days, litters of between 3 and 9 young are born, each weighing about 0.5 g. The young are weaned at 22 to 25 days. The breeding season lasts from April to September and a female may have 2 or 3 litters during this time.
Common shrews are short-lived and rarely survive more than a year. They are generally solitary animals, occupying a home range of 370 to 630 m2, which they mark using scent glands. While there may be some overlap of these home ranges, common shrews will fight vigorously to defend their territories from interlopers.
Their main predators are owls, but they are also taken by kestrels, stoats, weasels,
foxes and domestic cats. General habitat degradation is also a significant threat. The
accumulation of toxins through the pesticides and pollutants that are within its diet
means that the common shrew can be used as an indicator for monitoring pollution
in terrestrial habitats.
Did you know?:
Alternative names for the common shrew are Eurasian shrew, shrewmouse or
ranny. The red tips of a shrew’s teeth are the result of deposited iron salts and this
is thought to help the teeth resist wear.
Many superstitions surround shrews; they were thought to cause lameness if they
ran over sleeping cattle.
Conservation:
Like all shrews, the common shrew is protected under Schedule 6 of the Wildlife and Countryside Act 1981 and the Wild Mammals (Protection) Act 1996. A licence is required for the trapping or killing of shrews. Shrews of all species suffer high mortality in traps unless adequate food is provided and traps are checked regularly.
Distribution:
The common shrew is widespread, but probably under recorded, throughout Cornwall, but it is absent from the Isles of Scilly. In Britain the common shrew is found throughout the mainland, and on some of the islands. It is also found across Northern Europe and Scandinavia and as far east as Siberia.
Records:
2007-2012: 254
2002-2007: 942
Pre-2001: 332
Total: 1528
Survey Methods:
Small mammal trapping. Cat kill records. Owl pellet analysis. Incidental sightings–
bird feeders, mouse traps, live sightings, and dead animals found in discarded bottles. Hair tubes. Corrugated iron sheets used as refugia.
