This largely nocturnal species (5) inhabits burrows during the day and emerges to feed on invertebrates at night (2). They dive under water to obtain prey such as freshwater shrimps and caddis fly larvae, and the occasional frog newt or small fish may be tackled (2). When diving, the water-resistant fur holds bubbles of air that give the shrew a silvery appearance (4). They can also hunt on land for worms, beetles and other terrestrial invertebrates (4). Shrews are well known for their voracious appetites; water shrews must eat about half their own body weight in food every 24-hours to stay alive (6). Unusually amongst mammals, this species has venomous saliva, which aids in stunning prey (2). This species frequently grooms itself carefully, especially after diving. Water is removed by shaking and scratching, and also by squeezing through their narrow burrows (6). Water shrews are solitary animals, and hold territories (2). They do not hibernate, but are active throughout the year (2). Breeding takes place between April and September (5); during this time 1 or 2, but occasionally 3 litters of 3-15 young are produced in a nest of woven grasses (2) after a gestation period of 14-21 days (4). The lifespan is short (between 14 and 19 months); adults die after breeding, and the young breed the following year (2). Predators include tawny owls, barn owls, foxes, predatory fish and kestrels (2).

The water shrew is the largest of the British shrews (2); it has black upper parts and a whitish underside, between which there is a clear demarcation (4). Typically for most shrews, the snout is long and the eyes and ears are small (2). The fur is short and dense, and there are often tufts of white around the eyes and on the ears (2). Stiff hairs border the feet and form a keel on the underside of the tail (2), which aid in swimming (4). This species is a 'red-toothed shrew'; iron is deposited in the enamel of the tooth-tips, making them more resistant to wear-and-tear, and giving them a red appearance (6).

The water shrew has a large range extending from the British Islands eastwards to Lake Baikal, Yenisei River (Russia), Tien Shan (China), and northwest Mongolia. In the Mediterranean is ranges from northern Spain eastwards to Bulgaria.In Europe it is generally widespread throughout, with the exception of southern Iberia. It occurs only sporadically on the Balkan peninsula, where it is largely restricted to the mountains. It occurs from sea level to over 2,500 m (Stone 1995). The distribution of the species recently expanded southwards in Italy owing to a new record in the Sila massif (Aloise et al. 2005).

Neomys fodiens occurs throughout Eurasia, to western Siberia, northern Asia Minor, the Pacific coast of Siberia, and North Korea.

Biogeographic Regions: palearctic (Native )

Occurring throughout much of continental Europe, water shrews have a wide distribution in England, are quite common in Wales but rare in areas of northern and western Scotland (5). It is also found on several large offshore islands, including the Isle of Wight, Anglesey, Skye, Mull and Arran. It is absent from Ireland, the Channel Islands and the Scillies (2).

A darkly colored shrew with a white underside. Coloration on dorsal and ventral sides are sharply demarcated. A fringe of bristles runs along the ventral surface of the tail and on the paws which are thought to serve as a swimming aid. Teeth have red tips. Females have five pairs of mammae.

Average mass: 15 g.

Average basal metabolic rate: 0.328 W.

Type for Neomys fodiens
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Mammals
Sex/Stage: Male;
Preparation: Skin; Skull
Collector(s): R. Young
Year Collected: 1899
Locality: Montrejeau, Haute-Garonne Department, Midi-Pyrenees, France, Europe

Habitat and Ecology

Systems

• Terrestrial
• Freshwater

Found on the banks of both standing or flowing fresh water and adjacent areas.

Terrestrial Biomes: forest

Aquatic Biomes: lakes and ponds; rivers and streams

This semi-aquatic species is found close to water, in stream banks, ponds, rivers, reed-beds and fens, with a particular preference for watercress beds (2). However, it may also occur away from water in damp woodlands (4), and hedgerows (5).

These shrews forage almost exclusively underwater, efficiently preying on aquatic invertebrates such as snails, mollusks, freshwater insects, and also small vertebrates such as fish, amphibians and frogs. Prey are weakened by a poisonous secretion from the submaxillary gland. They generally forage by taking a dive that can last up to 20 seconds. After coming onto land, water shrews quickly run into their burrows and emerge a moment later almost dry, after coming through the tight squeeze of the tunnel where the water is absorbed by the soil. The process is then repeated a few meters away along the stream bank. Water shrews are also known to eat some terrestrial insects as well, such as dipteran larvae.

Average lifespan

Status: wild: 3.0 years.

Average lifespan

Status: captivity: 1.6 years.

Maximum longevity: 3.1 years (captivity) Observations: Unverified reports, which appear plausible, suggest that these animals may live up to 3.1 years of age in captivity, though they rarely live more than 1 year in the wild (http://members.chello.at/natura/shrew/index.html).

The breeding season in England occurs fom April to September, with multiple litters per season. Litter size can be between 3 and 12, more commonly 5 or 6. Gestation lasts approximately 20 days, and lactation twice that. Sexual maturity is reached between 6 and 8 months.

Average birth mass: 0.78 g.

Average gestation period: 20 days.

Average number of offspring: 5.

Average age at sexual or reproductive maturity (male)

Sex: male: 106 days.

Average age at sexual or reproductive maturity (female)

Sex: female: 106 days.

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 0
Species: 7
Species With Barcodes: 1

Quite common within its geographical range.

IUCN Red List of Threatened Species: least concern

Partially protected in the UK under Schedule 6 of the Wildlife and Countryside Act, 1981 (3). Listed under Schedule III of the Bern Convention, and classified as a Species of Conservation Concern under the UK Biodiversity Action Plan, although not a priority species (7).

Population

Population Trend

Major Threats

Drainage schemes (2) and the modification of riverbanks and riparian vegetation resulting from river engineering and agricultural intensification are likely threats (5). As this species is at the top of a semi-aquatic food chain, it may be highly susceptible to the effects of agrochemicals. Furthermore, any contaminants entering the water can reduce prey availability (5). Loss of continuous hedgerows and a decline in hedgerow quality may also be a problem, as for many species of mammal (5).

Conservation Actions

Water shrews are never very abundant (2), and their populations have a patchy distribution and are short-lived (5); it is therefore very difficult to detect whether the species is threatened (2). Schedule 6 of the Wildlife and Countryside Act protects all shrews from trapping without a licence (3).

No negative impacts known.

These shrews eat the larvae of insects which some humans find bothersome.