Description: Pygmy shrews are very small. Apart from their size, 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 smaller than both the common shrew and water shrew and have a more domed head. The fur on their back is greyish brown and they have a proportionally longer and thicker tail than the common shrew.
Size: Head and body 40-60mm, tail 32-46mm proportionately longer than the common shrew
Weight: 2-6g. Weight may reduce by up to 28% in winter.
Lifespan: They have a very short life span and it is uncommon for them to survive for more than 12 months.
Breeding: Pygmy shrews breed between April and October and usually have two or three litters of 5-7 young. They become sexually mature the following spring. Mortality of young shrews is very high.
Habitat: Can be found almost anywhere – parks and gardens, hedgerows, farmland, woodlands, grassland, etc. They are more common on moorland than common shrews.
Diet: Mainly insects, woodlice and spiders. They are not such good burrowers as common shrews so rarely eat earthworms. Need to eat regularly, at least every 2-3 hours as they have a very high metabolic rate. They need to eat 125% of their body weight each day.
General ecology: Shrews are very territorial and only socialise during the mating season. They can be quite aggressive when they meet other shrews. Each shrew will have a territory of about 500-2000m2. They are active both at night and in the daytime and do not hibernate in winter, though they do become less active. Because they need to eat regularly they may often be seen foraging. They do not “twitter” in the same way as common shrews but they may make sharp high pitched sounds if they meet other shrews. They make their nests in leaf litter or under dense vegetation, making “surface tunnels” and often using burrows formerly used by other small mammals. They have a good sense of smell but poor eyesight.
Distribution and main sites: Widespread in the UK, including Northern Ireland and Outer Hebrides, where common shrews are absent, but not in Shetland or the Scilly Isles. They were, until recently, the only shrew to be found in Ireland. A recent estimate puts the number of pygmy shrews in Great Britain at over 8.5 million. Distribution on the above map mainly reflects local surveys but these resourceful animals may be seen almost anywhere. Widely distributed in Shropshire but under-recorded.
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: Pygmy shrews are not an endangered species, but they are protected under Schedule 6 of the Wildlife and Countryside Act (1981
Threats: Main threats to their survival are changes in land use, loss of hedgerows, woodland and green corridors. Pesticides, herbicides, etc., are also a threat. They also have various predators including cats, owls, foxes and other birds of prey.
Main recording methods: Small mammal surveys are carried out, under licence, using humane traps (Longworth and/or BioEcoSS tube traps) to record the population of specific areas. Special care should be taken when trapping shrews as the risk of death is much higher than with other small mammals due to their high metabolic rate. Sufficient suitable bait such as blowfly larvae or casters must be provided. Trapping should only be carried out under licence. Longworth traps are often used with shrew holes to allow shrews to escape. Pygmy shrews may not trip the traps unless set lighter than normal. Common field signs include pathways in undergrowth. Bones and fragments may be found in owl droppings, for example, but may be difficult to identify. Dead shrews are more commonly found than those of other small mammals as they have glands that excrete a foul-tasting liquid that some predators, particularly cats, find distasteful.
Did you know? During the winter when they become less active, a shrew’s body shrinks so that they need less food to survive. Their overall body mass may shrink by up to 28%.
Text – Charlotte Huntly, with particular thanks to the Mammal Society, the Wildlife Trusts and Wikipedia; with additions by Malcolm Monie