Water Shrew Welfare: Venomous Semi-Aquatic Mammals

Water shrews are fascinating semi-aquatic mammals with venomous saliva. Their welfare depends on clean, invertebrate-rich waterways and undisturbed bankside habitat.

Key Facts

Water shrews are the UK's largest shrew and the only venomous British mammal
Their venom, delivered through grooved teeth, can paralyse prey including small frogs
They dive for aquatic invertebrates and small fish, using air trapped in their fur for buoyancy
Water shrews require clean, well-oxygenated water with diverse invertebrate communities
Pollution that reduces aquatic invertebrate diversity directly reduces their food supply
They use burrows in stream banks and are vulnerable to flood events and bank erosion

Welfare Considerations

Water shrew welfare is directly linked to water quality. They are indicators of healthy, clean waterways - populations disappear quickly from polluted or over-managed streams. Their need for diverse aquatic invertebrates means that agricultural runoff, sedimentation from overgrazing, and channelisation of streams all reduce welfare. Bank management that removes dense vegetation for flood control destroys burrow networks and cover. Sympathetic river bank management that retains dense riparian vegetation and minimises bank disturbance is the most effective welfare intervention.

What You Can Do

Support river restoration projects that restore natural bank structure
Advocate against channelisation of streams and rivers in flood management planning
Reduce agricultural runoff by supporting buffer strip creation alongside waterways
Monitor water shrew presence at local waterways as part of mammal survey work
Report water shrew sightings to the Mammal Society recording scheme