Possible water shrew

[vole-woman]

I was watching water voles this evening and suddenly there was a commotion and a shrew shot out from somewhere under the bank and swam off round the corner. It looked dark-furred - but then it was wet.

What are the chances it was a water shrew? Or was it more likely to have been a common shrew having a swim?

[The Woodman]

That's an interesting question. Water Shrews have distictive fur coloration - black dorsal and white ventral and will dive for fun. When underwater they look like quicksilver due to air trapped in the fur. It's rare to see other shrews swim, from memory I recall only seeing a common shrew swim a short distance.

The habitat might suggest WS, but don't rule out the other spp. Depending on the cause of the commotion, I would imagine any shrew would take to the water in an attempt to escape from a predator or an dominant territorial male. They fight regularly and are very vocal at high frequencies.

[vole-woman]

Thanks. Are there any special field signs I can look out for?

[The Woodman]

You could resort to live trapping to establish presence - caveat - check the legality of trapping shrews!

I've occassionally seen them fishing for gammarus and other inverts in the daytime. They repeatedly dive in, catch and recover to eat from a favoured place.

The Mammal Soc. did a survey a couple of years ago using baited (fly pupae) tubes that accumulated WS droppings to prove presence. You might find reference to that study on tinterweb.

[vole-woman]

You have to have a licence to trap shrews, don't you? I wouldn't anyway, though - haven't got the time right now as my husband's in hopsital and needing visiting twice a day. But I'll keep a sharp look out in case I see it again.

[Rob_D]

A few bait tubes would be easy enough as you can leave them for a couple of weeks. I used dried mealworms instead of maggot casters because they're more convenient.

http://www.sussexotters.org/pdf/How%...w%20survey.pdf

Water Shrew scat is very different to voles - full of aquatic insects rather than plants. You might need a microscope to be sure if it's common shrew or water shrew. Not always so easy to collect though, because the tubes get wet easily, and whichever little blighters go in don't often wipe their wet and mucky feet.