The water shrew is a dapper little creature with dense velvety jet black fur on top and whitish fur underneath.

  The casual observer would be forgiven for regarding it as one of the cutest denizens of the canal bank with its long pointed snout and white tufted ears.

In fact this small creature packs a punch way above its size. Despite weighing no more than two 10p coins, it puts up a ferocious fight when defending its territory from other shrews, and has red tipped fangs and venomous saliva to stun prey to stop it struggling.

 

If it were to bite a human, it would produce a burning pain or red rash that could last for a few days.

A nationwide survey by the Mammal Trust for the Environment Agency revealed that the water shrew is widely distributed across the country, with a concentration in central and eastern England.

 

In Wiltshire, the Biological Recording Centre (BRC), based at the Wiltshire Wildlife Trust in Devizes, has only 30 records, and these are mostly very old.

Where sightings appear along the Kennet & Avon Canal, they are clustered either around Bradford on Avon in the west or Pewsey towards the east of the county. “We don’t know quite why this should be, but our records are desperately in need of updating – few people have sent us any records of water shrews on the canal for a very long time,” says Hannah Price of the BRC.

Part of the problem is that water shrews are hard to spot, so when a dead water shrew was brought into the Trust’s offices recently, staff took the opportunity to take a good look at it.

“It was the casualty of a cat, but people shouldn’t be embarrassed to report such deaths because they can be an important source of records,” say Hannah.

 

In the water, the water shrew has to paddle fast to stay under the surface because air trapped under its fur makes it buoyant.

This layer of bubbles can also give away its presence - the next time you see a few bubbles

But water shrews are more likely to be heard than seen, as they communicate with each other by high-pitched squeaks and twitters, as well as by scent.

Water shrews tend to live alone, usually but not always near water. The survey highlighted that where previously it was thought they preferred fast-flowing rivers and streams, they do in fact enjoy a whole range of still water habitats, including canals.

They dig a shallow burrow system with a tunnel leading to a nest chamber, which is lined with a ball of grass, roots and moss.

The burrow system may have an underwater entrance, making it even harder to see.

Being so small, the water shrew quickly burns up its energy reserves and so has to feed more or less continuously, seeking out worms, insect larvae, snails, crustaceans, spiders, fish, frogs and tadpoles.

It hunts along the bottom of a waterway, grasping stones with its feet and turning them over, before carrying prey to the bank to be eaten.

While there was no hard evidence that water shrews are declining in numbers overall, they are known to be very vulnerable to pollutants and pesticides in the water, which they ingest either through their prey or by grooming their fur.

The survey pinpointed that, in some areas where numbers have fallen drastically, this is probably due to the destruction of habitat by the draining of waterways and wetlands and pollution.

“It would be great to get a really clear picture of what is happening to water shrews in Wiltshire and Swindon,” says Hannah, “so please send any sightings to the BRC either submitting them via our online recording form at:  www.wsbrc.org.uk

or by post or by telephone on 01380 725670.