Common Shrew
Overview
 
The Common Shrew or Eurasian Shrew, Sorex araneus, is the most common shrew
Shrew
A shrew or shrew mouse is a small molelike mammal classified in the order Soricomorpha. True shrews are also not to be confused with West Indies shrews, treeshrews, otter shrews, or elephant shrews, which belong to different families or orders.Although its external appearance is generally that of...

, and one of the most common mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...

s, throughout Northern Europe
Northern Europe
Northern Europe is the northern part or region of Europe. Northern Europe typically refers to the seven countries in the northern part of the European subcontinent which includes Denmark, Estonia, Latvia, Lithuania, Norway, Finland and Sweden...

, including Great Britain
Great Britain
Great Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles...

, but excluding Ireland
Ireland
Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...

. It is 55 – long and weighs 5–12 g (0.17636981052556–0.423287545261344 oz), and has velvety dark brown fur with a pale underside. Juvenile shrews have lighter fur until their first moult. The Common Shrew has small eye
Eye
Eyes are organs that detect light and convert it into electro-chemical impulses in neurons. The simplest photoreceptors in conscious vision connect light to movement...

s, a pointed, mobile snout, and red-tipped teeth.
Encyclopedia
The Common Shrew or Eurasian Shrew, Sorex araneus, is the most common shrew
Shrew
A shrew or shrew mouse is a small molelike mammal classified in the order Soricomorpha. True shrews are also not to be confused with West Indies shrews, treeshrews, otter shrews, or elephant shrews, which belong to different families or orders.Although its external appearance is generally that of...

, and one of the most common mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...

s, throughout Northern Europe
Northern Europe
Northern Europe is the northern part or region of Europe. Northern Europe typically refers to the seven countries in the northern part of the European subcontinent which includes Denmark, Estonia, Latvia, Lithuania, Norway, Finland and Sweden...

, including Great Britain
Great Britain
Great Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles...

, but excluding Ireland
Ireland
Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...

. It is 55 – long and weighs 5–12 g (0.17636981052556–0.423287545261344 oz), and has velvety dark brown fur with a pale underside. Juvenile shrews have lighter fur until their first moult. The Common Shrew has small eye
Eye
Eyes are organs that detect light and convert it into electro-chemical impulses in neurons. The simplest photoreceptors in conscious vision connect light to movement...

s, a pointed, mobile snout, and red-tipped teeth. It 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 burst of activity.

Territory

The Common Shrew is found in the woodland
Woodland
Ecologically, a woodland is a low-density forest forming open habitats with plenty of sunlight and limited shade. Woodlands may support an understory of shrubs and herbaceous plants including grasses. Woodland may form a transition to shrubland under drier conditions or during early stages of...

s, grassland
Grassland
Grasslands are areas where the vegetation is dominated by grasses and other herbaceous plants . However, sedge and rush families can also be found. Grasslands occur naturally on all continents except Antarctica...

s, and hedgelands of Britain, Scandinavia
Scandinavia
Scandinavia is a cultural, historical and ethno-linguistic region in northern Europe that includes the three kingdoms of Denmark, Norway and Sweden, characterized by their common ethno-cultural heritage and language. Modern Norway and Sweden proper are situated on the Scandinavian Peninsula,...

, and Eastern Europe
Eastern Europe
Eastern Europe is the eastern part of Europe. The term has widely disparate geopolitical, geographical, cultural and socioeconomic readings, which makes it highly context-dependent and even volatile, and there are "almost as many definitions of Eastern Europe as there are scholars of the region"...

. Each shrew establishes a home range of 370 sqm. Males extend these boundaries only during breeding season, to find females. The Common Shrew is extremely territorial
Territory (animal)
In ethology the term territory refers to any sociographical area that an animal of a particular species consistently defends against conspecifics...

 and becomes aggressive when another shrew enters its home range. It makes its nest underground or under dense vegetation.

Diet

The shrew's carnivorous
Carnivore
A carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of animal tissue, whether through predation or scavenging...

 and insectivorous
Insectivore
An insectivore is a type of carnivore with a diet that consists chiefly of insects and similar small creatures. An alternate term is entomophage, which also refers to the human practice of eating insects....

 diet consists mostly of insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...

s, slug
Slug
Slug is a common name that is normally applied to any gastropod mollusc that lacks a shell, has a very reduced shell, or has a small internal shell...

s, spider
Spider
Spiders are air-breathing arthropods that have eight legs, and chelicerae with fangs that inject venom. They are the largest order of arachnids and rank seventh in total species diversity among all other groups of organisms...

s, small mice
MICE
-Fiction:*Mice , alien species in The Hitchhiker's Guide to the Galaxy*The Mice -Acronyms:* "Meetings, Incentives, Conferencing, Exhibitions", facilities terminology for events...

 and worms. Shrews need to consume 200-300% of their body weight each day in order to survive. A shrew must eat every two to three hours to achieve this goal. This means that a shrew may starve if it finds no food for as little as 5 hours. They do not hibernate in the winter months because their bodies are too small to hold sufficient fat reserves.

Shrews have poor eyesight
Visual perception
Visual perception is the ability to interpret information and surroundings from the effects of visible light reaching the eye. The resulting perception is also known as eyesight, sight, or vision...

, but use their excellent sense of smell
Olfaction
Olfaction is the sense of smell. This sense is mediated by specialized sensory cells of the nasal cavity of vertebrates, and, by analogy, sensory cells of the antennae of invertebrates...

 and good hearing
Hearing (sense)
Hearing is the ability to perceive sound by detecting vibrations through an organ such as the ear. It is one of the traditional five senses...

 to locate food. Using these senses, a shrew can locate prey up to 12 centimetres (5 in) 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 five to seven baby shrews. A female usually rears two to four litters each year. The young are weaned and independent by 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.

Chromosomal polymorphism

The chromosome number (karyotype
Karyotype
A karyotype is the number and appearance of chromosomes in the nucleus of an eukaryotic cell. The term is also used for the complete set of chromosomes in a species, or an individual organism.p28...

) of Sorex araneus varies from one individual to another. This is an example of chromosomal polymorphism
Polymorphism (biology)
Polymorphism in biology occurs when two or more clearly different phenotypes exist in the same population of a species — in other words, the occurrence of more than one form or morph...

; the variability occurs as a result of chromosome fusions or disassociations.

Protection and population

The Common Shrew is not an endangered species
Endangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...

, but in Great Britain
Great Britain
Great Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles...

 it, like other shrews, is protected from certain methods of killing by the Wildlife and Countryside Act of 1981.

In Britain, shrews can be found at densities up to one per 200 sqm in woodlands. The population is controlled by many predators including owl
Owl
Owls are a group of birds that belong to the order Strigiformes, constituting 200 bird of prey species. Most are solitary and nocturnal, with some exceptions . Owls hunt mostly small mammals, insects, and other birds, although a few species specialize in hunting fish...

s, weasel
Least Weasel
The least weasel is the smallest member of the Mustelidae , native to Eurasia, North America and North Africa, though it has been introduced elsewhere. It is classed as Least Concern by the IUCN, due to its wide distribution and presumably large population...

s, stoat
Stoat
The stoat , also known as the ermine or short-tailed weasel, is a species of Mustelid native to Eurasia and North America, distinguished from the least weasel by its larger size and longer tail with a prominent black tip...

s, and fox
Red Fox
The red fox is the largest of the true foxes, as well as being the most geographically spread member of the Carnivora, being distributed across the entire northern hemisphere from the Arctic Circle to North Africa, Central America, and the steppes of Asia...

es. A liquid produced by glands on the skin make shrews taste rather unpleasant to domestic cat
Cat
The cat , also known as the domestic cat or housecat to distinguish it from other felids and felines, is a small, usually furry, domesticated, carnivorous mammal that is valued by humans for its companionship and for its ability to hunt vermin and household pests...

s.

There has been a recent decline in common shrew populations due to increased use of herbicide
Herbicide
Herbicides, also commonly known as weedkillers, are pesticides used to kill unwanted plants. Selective herbicides kill specific targets while leaving the desired crop relatively unharmed. Some of these act by interfering with the growth of the weed and are often synthetic "imitations" of plant...

s.

External links

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