Camera trap video – Kate Long
Description: Water shrews have dense velvety fur, black on their backs and whitish underneath, a long pointed nose, tiny eyes, small ears and usually tufts of white hair on the ears and/or around the eyes. They also have white hairs on their feet and the underside of their tail, the latter acting as a keel. Their fur is denser than in other shrews as it acts as a form of insulation against the cold and wet. The main visible feature distinguishing them from mice and voles is their pointed nose. The easiest way of distinguishing them from other shrews is by size as they are the largest of the British shrews. The fur on their backs is also blacker than that of the common or pygmy shrews.
Size: Head and body 67-96mm, tail 45-77mm
Lifespan: Normally no more than about 19 months.
Breeding: Females will normally have two or three litters of 5-15 young between April/May and September. The adults tend to die off after breeding and the young overwinter and become sexually mature the following spring.
Habitat: They are semi-aquatic so are mostly found close to water, including banks of streams, rivers, ponds, ditches, reed beds and fens. They particularly like watercress beds!
Diet: Their main diet consists of freshwater shrimps, pond skaters and caddisfly larvae but they may also eat frogs, newts, snails and beetles.General ecology: Shrews are very territorial and only socialise during the mating season. They are active both at night and in the daytime and do not hibernate in winter, though they do become less active. They make a nest woven from dry grass, usually in a burrow or under a log not far from water.
Distribution and main sites: Can be found throughout most of mainland Britain and some of the larger islands but not in Northern Ireland and some outlying islands (e.g. Scillies and Channel Islands). They are not as abundant as other types of shrew with a recent estimate suggesting there are around 715 000 in Britain. Distribution on the above map mainly reflects local surveys and recorders, but these resourceful animals may be seen almost anywhere there is water close by.
Local survey history: Small mammal surveys are regularly carried out in various locations, including Whitchurch, Shrewsbury, Preston Montford, Ironbridge and Wenlock Edge, often by, or on behalf of, organisations such as Shropshire Mammal Group, National Trust, Shropshire Wildlife Trust or Ironbridge Meadows Group.
Conservation status: Water shrews are not seen as particularly threatened, but it is difficult to tell how abundant they are, as they are not found as often as other shrews since they are restricted to riparian habitats. Where long-term studies have been conducted they still appear to be quite numerous. Like other shrews they are protected under Schedule 6 of the Wildlife and Countryside Act (1981).
Threats: Main threats are water pollution and changes in land use where drainage systems are changed or river banks cleared. Pesticides and herbicides are also a threat both directly and indirectly through their food supply. They also have various predators, including owls, foxes and cats.
Main recording methods: Can be caught in live traps when these are placed near water where water shrews can sometimes be seen swimming or even heard squeaking. Bait tubes have also been used and the droppings left analysed. Those of water shrews are distinguishable by the remains of shrimps and other aquatic species.
Did you know? Water shrews have venomous saliva which helps to stun their prey, particularly larger prey such as frogs and newts. Although their teeth will rarely puncture human skin, it can still cause an unpleasant rash.
Text – Charlotte Huntly, with particular thanks to the Mammal Society, wildlife trusts and Wikipedia
© Shropshire Mammal Group 2020