Walk This Waterway Wednesday- The water shrew

Water shrew (Neomys fodiens)

Hi Emily here again :) . This week I have decided to focus on a very unusual creature and one of Britain's least known mammals - the water shrew (Neomys fodiens). This species is so unusual as its able to secrete a mild toxin into its saliva. This venomous saliva enables them to stun their prey and means they can tackle animals up to 60 times heavier than themselves!

As water shrews are able to dive up to 70cm and hunt underwater, their prey tends to be species such as caddis fly larvae, water skaters and freshwater shrimps. Occasionally small fish, newts, snails, beetles and frogs may also be eaten. Water shrews are mostly nocturnal, being mainly active just before dawn. 

Waterways play a vital role in the life of water shrews with individuals travelling up to 160m along the water's edge trying to find both food and shelter. Water shrews dig networks of small chambers and burrows, which they line with leaves and grass to keep the warm. They do not hibernate during winter as their fur is thicker than other shrew species.  

Many studies have shown that water shrew populations may be decreasing as a result of pollution, pesticide use and habitat loss. The recent population review undertaken by the Mammal Society predicted that the population sizes of shrews will decrease in the future too. However, we really don't have enough data on the densities of these elusive species, but you can help. 

                                                                                                                                   UK map showing in purple the areas where water shrews are known to live. 

You can help us to monitor water shrews by downloading the Mammal Mapper App and participating in our latest project “Walk This Water Way” Although mammals can be hard to spot, any sightings or signs along a linear feature such as a waterway can help us gather some very important data! All you have to do is walk at least 600m of waterway and record your sightings in the app. You’ll need to enter the Survey ID as WTWW.  More information about Walk This Water Way can be found here.